Apologies for the delay on this one folks - work, school, and life got ahead of me and I really wanted to compile the best guide that I could for all things squat. I hope you find this useful and informative!
Hello everyone!
In an effort to keep the subreddit and its wiki filled with good and useful information, we are compiling guides for the main lifts (deadlift, squat, bench, potentially others). These guides will be added to the wiki and posted as posts as they are completed. The goal of these guides is to provide basic lift information, descriptions of some common variations, equipment considerations, related and complimentary exercises, additional resources for further reading, and to showcase incredible women (and non-binary folks) performing these lifts.
This is the third entry in this lift series. Check out the first entry, The Deadlift Guide and second entry, The Bench Press Guide in the FAQ!
If you have suggestions regarding things that should be added to these guides, or other subjects you'd like to see in the wiki, please message the mods!

The Squat

Squat Form and Variations

This squat guide will generally be describing barbell squats, though these exercises can also be performed with body weight, dumbbells, or kettlebells.
Stronger By Science has an in depth anatomical section for every muscle and skeletal component active during a squat. The squat is primarily a lower body exercise, working the quadriceps especially (front thigh muscles), hamstrings (back thigh muscles), and gluteus muscles (butt) the most, but also involving the upper back and shoulders, lower back, and abdominal muscles.
The squat, like the deadlift and bench press are compound exercises meaning they work multiple muscle groups at the same time. In comparison, isolation exercises tend to focus on one or just a few muscles at a time – most exercise machines in the gym are great for isolation work, whereas free weight exercises involve more muscles.
Proper form for a squat is highly personal and incredibly variable, dependent on individual anatomical features. The length of your torso, the length of your femurs, the specific anatomy of your hip joints, and flexibility at both hip and ankle joints can vastly impact the ideal form for your squat. These factors also explain why your perfect form squat will probably look very different compared to someone else’s perfect form squat.
The width and depth of your ideal squat can vary wildly compared to someone else. Squat University just released a 12 minute video: How To Squat For Your Anatomy (DEPTH & STANCE WIDTH) which goes over how to find your ideal foot width in order to squat as deeply as possible while maintaining a neutral spine. If you’re short on time, they also posted a truncated 5 minute version of this video to the Squat University Instagram.
However, there are several universal basic requirements for a technically optimal squat regardless of individual variance:

• As with the deadlift, the weight should remain over the midfoot (where the ankle turns into the top of your foot) for the entirety of the movement.
  
• From a technique standpoint, this means that the chest and the hips should be rising at the same time and prevents “good morning”-ing your squat where the hips rise faster than the chest.
  
• The spine should be stable/neutral (not hyper- or hypo-extended) through the movement.
  
• Knees track your toes – this means your knees will move in line with the angle of your toes through the lift. If your feet are pointing straight ahead, your knees will move straight ahead. If your toes are rotated outward, your knees will move in the same direction.
  
• Proper breathing and bracing techniques are used to maintain tension and stability within the body during the lift.
  
• You’ll want to have your foot engaged as a tripod, even in shoes, for a firm and stable squat. This means that your heel, big toe, and pinky toe will all be in solid contact with the ground (or the sole of your shoe) to create a stable base for your squat. This will help keep your weight evenly distributed, keep your balance, and ensure the center of gravity (your body + however much weight you’re squatting) over your midfoot.
  
• Create tension in your hips. A common cue for this is to “screw your feet into the floor” or “try to spread the floor” depending on your squat width. Stronger By Science covers this and full body tension in their comprehensive squat guide.
  
• Don’t use momentum to get you through the lift. It should be a controlled movement and you shouldn’t “bounce” up out of the hole to power you back to standing up fully.
  
• Don’t waste energy with an inefficient walk out. This post concisely goes over why you should have a short walk out once you get the bar on your body.
  
• Foot Placement again is highly personal. For figuring out your ideal stance width (article), stance width (video) and foot angle (article), foot angle (video) you’ll have to do some trial and error to find which positions fit best for you and your goals.
  
• Squat Depth For a competition level depth squat, you’ll want to at least “break parallel” to get all white lights and succeed the lift– this is when the crease at your hip joints becomes lower than your knees (visually, the patella or knee cap) so your femurs (thigh bones) are no longer parallel to the floor. During a squat, your femur orientation changes from perpendicular to the floor when you’re fully upright, and as you descend, should become parallel to the floor, but then your hip joints (where your thigh bone joins your pelvis – the crease when you bend over or squat down) should continue at least a little bit below the knee joints, even if you’re not competing.
  

There is a lot of misinformation regarding how “safe” squats are in general, with special attention for danger to the lumbar spine (lower back) and your knee joints. An unfathomable number of sources claim that deep squats (at or below parallel) are no good for your knees and lumbar spine. According to a huge meta-analysis of over 164 sports medicine, physiology, and orthopedic scholarly articles: “When compared with half and quarter squats, in the deep squat, lower knee joint and spinal joint stress can be expected. Provided that the technique is learned accurately under expert supervision and with progressive training loads, the deep squat presents an effective training exercise for protection against injuries and strengthening of the lower extremity. In conclusion, contrary to commonly voiced concern, deep squats do not contribute increased risk of injury to passive tissues.”

• How Far Should Your Knees Go?: Another common anti-squat myth is that your knees should never go past your toes. This is generally anatomically impossible for most people, and trying to abide by that “rule” will likely be more painful and risky than squatting properly. Squat University has an excellent article debunking this, with helpful comparison images to prove a point. If you prevent your knees from extending past your toes as you squat, you will be unbalanced (literally, your center of gravity will be all wrong) and you will be unable to keep the barbell or other weight over the midfoot, which is dangerous and will eventually result in an injury.

Main Types of Squats

Back Squat
Here is an excellent visual representation of how torso angle changes in front squats, high bar back squats, and low bar back squats. Note that the bar path in each variation keeps the bar over the midfoot. Because each variation has the bar resting on different bodily locations, the torso angle required to keep the bar over midfoot is different as well.
High Bar vs Low Bar: Where you place the bar across your back for a back squat can largely be left up to preference and performance. If you can squat more doing one variation or you just like one better, feel free to stick to that bar position. Depending on your anatomy and body mechanics, high or low bar squat may be more comfortable, easier, or otherwise more optimal for you as an individual. In terms of lift mechanics, they are functionally identical. It really is down to preference/performance which bar position you go with for your back squat.

• High Bar Back Squat: For a high bar back squat, the bar will be resting on the upper trapezius muscles. It is not resting against the very base of your cervical spine. You’ll need to actively engage and flex your traps to keep the bar from grinding into the spinous process at the base of your neck.
  
• Low Bar Back Squat: For a low bar back squat, the bar will be resting about an inch lower, across the posterior deltoids.
  
• Front Squat: For this squat variation, the bar will be resting in front of your neck across your anterior deltoids. For some people, the front rack position is uncomfortable or impossible due to mobility issues. If that is the case, one can perform a front squat using an “I Dream Of Jeannie” type arm position. The important thing to remember with either position is to keep your elbows up, parallel to the floor. One more position option is to use straps to hold the bar in place and minimize stress on the joints of the upper extremities. Stronger By Science demonstrates the different options typically seen in front squats.
  

Squat Variations

• Zercher Squat – This is a variation of a front squat in which the barbell will be resting in the crooks of your elbows. As such, this can be very uncomfortable without some padding – knee sleeves or long sleeve shirts would be a bare minimum to protect from the knurling, but this is one type of squat that can actually benefit from the use of a barbell pad.
  
• Goblet Squat is another front-loaded squat performed using a dumbbell or kettlebell “racked” in your hands near your chest.
  
• Hack Squat and belt squats are machine assisted squat variations that can be especially useful in the case of working around an injury. Belt squats in particular help decrease the load on the spine while still getting plenty of work out of the legs.
  
• Pistol Squat (video link) – a challenging single leg squat exercise with functional strength benefits.
  

How-To Guides/Other Resources

• Stronger By Science’s “How To Squat” Guide
  
• Squat University blog archive – many of these articles are linked throughout this post, but here’s the collection of all of them.
  
• Squat University Squat “Technique Continuum” Article
  
• Squat University Youtube
  

Complimentary/Supplemental Exercises

• Leg Press - While success on the leg press will not translate 1:1 to a squat, these isolation exercises can be incorporated into a lower body workout to isolate the quadriceps and gluteus muscles. Strengthening those muscles will of course benefit any movements that use them, including the squat.
  
• Hip Thrust and Glute Bridges – Glute focused exercises that can be performed with body weight, resistance bands, and/or added weight (barbell, kettlebell, dumbbell, weight plates, another person). These can also be used as a warm up exercise for squatting, or on their own as part of a lower body workout. Here is another helpful compilation of hip thrust/glute bridge variations by Sohee Lee.
  
• Box Squat - With a chair, bench, plyo box, or other stable flat surface behind you, squat down until your butt touches the platform behind you. Either sit all the way down or do a touch and go of the platform and ascend. These help the lifter feel more comfortable sitting back into their heels during a squat and can also help recognize what appropriate depth feels like if the platform allows you to go to parallel or slightly below.
  
• Pause or Tempo Squat - Somewhat self-explanatory. Performing a “tempo” lift means slowing down the movement, leading to improved control and performance during a lift. Typically a tempo squat will have a slowed descent, a brief pause at the bottom, and a normal ascent (although ascent could be slowed as well). A pause squat has the lifter pausing the lift in the bottom of the movement. These variations can be performed to improve control, strength, and technique.
  
• Lunges - Unilateral leg exercises that come in many forms. Unilateral leg exercises are excellent for isolating muscles and also for addressing strength imbalances or weakness. If you have a strength imbalance, let your weaker side dictate how many reps/sets you do in order to allow it to catch up to the stronger side. Altering stride distance and torso angle can also help you customize your lift for comfort and for targeting specific muscles more than others.
  
• Bulgarian split squat - These are similar to lunges, except the back foot will be elevated and resting on something. Typically these are demonstrated with the back foot on a bench or plyo box, but this may add too much challenge with maintaining balance for some lifters. Using a smith machine with the bar set low and the back ankle hooked over it will work just the same and allow for improved balance during the movement. Other options include guide railing, a peg on a weight plate rack, or the cylindrical padding found on some decline benches to rest the back ankle on.
  

Equipment, Tools, Other Considerations

Stronger By Science Squat Equipment Rundown

• Lifters/Wedge Shoes – Generally when weightlifting, you should be wearing a shoe with a flat sole and little-to-no padding. Running shoes are no good for weightlifting because they compromise the stability of your foot with all that cushy padding. Remember, your foot should be making a “tripod” with the big toe, pinky toe, and heel to allow for even weight distribution and maximal stability. For squatting in particular, it may benefit you to have a raised heel (either a lifter shoe like the Nike Romaleo, Adidas Powerlift, and Reebok Legacy Lifter are the most popular examples of this type of shoe. You can also put a small weight plate or other flat, stable object beneath the heel of your flat-soled shoe to accomplish the same effect. The purpose of elevating the heel is to work around ankle mobility limitations and still allow for a deeper squat while maintaining an upright torso.
  
• Lifting Belts – tldr a belt won’t fix a problem you have with bracing or mechanics but if your lift and your bracing/breathing is solid, a belt is only going to improve your performance.
  
• Barbell Pads - Don’t use these for back squats. They decrease the stability of the bar across your back by turning it into a seesaw and thus decrease your stability and that of your lift. If you are getting sore or tender from the bar across your back, it is likely placed too high up on your shoulders and sitting across the spinous process of your vertebra(e). Shifting the bar down and ensuring a muscular shelf is created with your traps and/or deltoids (depending on high vs low bar squatting) will resolve this.
  
• Knee Sleeves/Wraps: Sleeves are generally compression garments to keep the joint warm and cozy, and may increase general awareness (proprioception!) of your knees during a lift to possibly improve technique/performance. Knee wraps actually alter some physics/mechanics of the knees during the squat by acting like mini springs to release energy back into you on the ascent, and can lead to increased squat weight and speed out of the hole.
  
• Resistance/Mini Bands - One way to increase the resistance or challenge of a squat is to add resistance bands at the knees. This forces you to apply more external force during the squat and can help prevent knee cave (valgus). These are also an excellent way to warm up – putting the bands around your knees or ankles and doing lateral (side to side) squats or “monster walks”, clamshells with the resistance bands around the knees, or side planks/lying hip abduction exercises with the bands around the knees are excellent workouts in their own right, or for warming up prior to squatting.
  

Other Considerations

• Knee Valgus: Your knees should follow the line of your toes, so depending on your feet placement should go quite a bit outwards. It’s an extremely common form issue for the knees to collapse inwards, known as valgus position. While this is more acceptable at weights very close to 1RM or the last rep of a hard set, if it is happening for every squat it reveals some weakness and might be a risk for injury. The good news is that it’s generally easy to address by improving strength and neuromuscular control of the glute medius muscle. This muscle is the major abductor for the hip, moving the leg away from the body. Some examples of strengthening exercises can be found in this video, and this technique can be used while squatting to help your knee stay outwards during the movement. A similar technique can be done with a small loop band placed just above your knees while squatting. Make sure to try these with bodyweight or light loads before using a band during working sets.

Badass Women Squatting Obscene Numbers

• Jessica Buettner squatting 419lbs/190kg x3
  
• Ciarra Hutton squatting 430 lbs
  
• Maddy Forberg, 320lbs/145kg
  
• Amanda Lawrence, 525lb single + 460lbs 3x8?!
  
• Stefi Cohen, 485lbs/220kg
  
• Crystal Tate, 700lb squat
  
• Chakera Ingram, 645 lb squat
  
• Jenn Rotsinger – 369lbs at 114lb BW
  
• Wei Ling Chen 210kg squat at 47kg bodyweight!
  

If you would rather see me talk about this than read, click here.
Winged Scapula are those shoulder blades that look like you could hook your fingers underneath them.
The term ‘winged scapula’ (also scapula alata) is used when the muscles of the scapula are too weak or paralyzed, resulting in a limited ability to stabilize the scapula. As a result, the medial border of the scapula protrudes, like wings.
In this guide, I will cover:

1. How winged scapula develop
2. Consequences of winged scapula
3. What can be done to correct this issue

TL;DR: Winged scapula are often a result of the shoulder blade not being able to glide freely on the ribcage due to compression within it (poor breathing mechanics). This causes the scapula to deviate outward in an attempt to find more movement. To fix this, we need to make sure the scapula can first glide on the ribcage first, then address the musculature that can help re-orient it on the ribcage.
How Winged Scapula Develop
Generally speaking, the primary goal of the scapula is to glide freely on the ribcage. It needs to do so to allow for movement to occur at the humerus and arm.
The scapula and humerus have a delicate interplay of motion known as Scapulo-Humeral Rhythm.
This is probably the most important thing your scapula is responsible for, so it needs to freely glide on the posterior (back) ribcage in order for that to happen.
In addition, the scapula is a concave (rounded inward) structure that is meant to sit on a convex (rounded outward) posterior ribcage. That is a reason why there is a slight outward curvature in the normal human spine.
Scapulo-Humeral Rhythm is primarily concerned with shoulder flexion, or moving the arm overhead. As the arm progressively moves upward, there should be a ratio of scapular upward rotation for every degree of humeral flexion.
The muscles responsible for this are primarily the Serratus Anterior and Low/Upper Traps. Scapular winging is usually associated with weakness or dysfunctional activation in one or multiple of these muscles.
The scapula also goes into varying degrees of internal/external rotation as well as anteiror tipping depending on the level of shoulder flexion.
If the scapula is lacking any of the aforementioned qualities, it will likely find the best possible orientation where it can glide on the ribcage effectively. This is often a "winged" state.
In addition, if an individual has a lateral pelvic tilt and/or trunk rotation to one side causing a forward shoulder, the shoulder that is more forward and lower is likely to have a more winged scapula than the other side.
Consequences of Winged Scapula
A primary consequence would be a lack of range of motion within the shoulder, primarily in the actions of:

• Internal Rotation - 70+ degrees is ideal
• Adduction - 30+ degrees is ideal
• Extension - 60+ degrees is ideal

If these movements are missing, you'll be missing a lot of movement capabilities within your shoulder.
This winged scapula orientation also often results in a forward translation of the humerus (forward shoulder) within the Glenohumeral joint which often causes impingement and subsequent discomfort.
On the front side of the body, this causes the pecs and other muscles to become tight and compresses the front side of the ribcage on that side, preventing it from expanding and that can limit breathing mechanics.
This can also affect the elbow. If the humerus is in this internally-rotated position, the forearm could also be biased towards too much pronation.
Very similarly to how femoral internal rotation and tibial external rotation causes a knee valgus, the forearm can try to find supination it is lacking up turning "out" (relative to the humerus) and cause an "elbow valgus", which can heavily stress the elbow.
What Can Be Done To Correct Winged Scapula
The first and foremost priority that is most often overlooked is the ribcage.
If the ribcage isn't positioned well, neither will the scapula. Then the humerus won't be either and it feeds down the chain.
So we should start with the ribcage and position that first to allow room for the scapula to "roam" on the ribcage, then address scapular position. This is the step most people miss and why many don't get lasting results (in my opinion & experience).
Step #1: Expand the Ribcage - Rockback Lat Stretch
We should start with addressing the front side of the ribcage to allow for expansion to occur there. When we inhale, the shoulders should translate backward and the scapula should posteriorly & downwardly rotate.
This activity will help gravity act "downward" on us to allow for expansion to occur in the front ribcage while also releasing the lat, a muscle that is often contributing to pulling the shoulder and scapula forward.
You'll know you can get expansion in your ribcage anteriorly when you have passed the Humeral Internal Rotation, Adduction, and Extension measurements above.
Step #2: Re-Orient the Scapula - 90/90 Side Plank with Wall Press
After we can get expansion in the ribcage, we can then put the scapula in a better place. Two muscles that are very important for this are the low traps and long head of the triceps. Notice where the longer head of the triceps attaches. If it contracts, it will pull the scapula back.
Those are the two main steps that should be respected in that order. Those are just two exercises that can help in this situation, but is by no means a comprehensive approach.
If you are interested in a full approach, I'd encourage you to get a posture assessment done.

If you would rather see me talk about this than read, click here.
Winged Scapula are those shoulder blades that look like you could hook your fingers underneath them.
The term ‘winged scapula’ (also scapula alata) is used when the muscles of the scapula are too weak or paralyzed, resulting in a limited ability to stabilize the scapula. As a result, the medial border of the scapula protrudes, like wings.
In this guide, I will cover:

1. How winged scapula develop
2. Consequences of winged scapula
3. What can be done to correct this issue

TL;DR: Winged scapula are often a result of the shoulder blade not being able to glide freely on the ribcage due to compression within it (poor breathing mechanics). This causes the scapula to deviate outward in an attempt to find more movement. To fix this, we need to make sure the scapula can first glide on the ribcage first, then address the musculature that can help re-orient it on the ribcage.
How Winged Scapula Develop
Generally speaking, the primary goal of the scapula is to glide freely on the ribcage. It needs to do so to allow for movement to occur at the humerus and arm.
The scapula and humerus have a delicate interplay of motion known as Scapulo-Humeral Rhythm.
This is probably the most important thing your scapula is responsible for, so it needs to freely glide on the posterior (back) ribcage in order for that to happen.
In addition, the scapula is a concave (rounded inward) structure that is meant to sit on a convex (rounded outward) posterior ribcage. That is a reason why there is a slight outward curvature in the normal human spine.
Scapulo-Humeral Rhythm is primarily concerned with shoulder flexion, or moving the arm overhead. As the arm progressively moves upward, there should be a ratio of scapular upward rotation for every degree of humeral flexion.
The muscles responsible for this are primarily the Serratus Anterior and Low/Upper Traps. Scapular winging is usually associated with weakness or dysfunctional activation in one or multiple of these muscles.
The scapula also goes into varying degrees of internal/external rotation as well as anteiror tipping depending on the level of shoulder flexion.
If the scapula is lacking any of the aforementioned qualities, it will likely find the best possible orientation where it can glide on the ribcage effectively. This is often a "winged" state.
In addition, if an individual has a lateral pelvic tilt and/or trunk rotation to one side causing a forward shoulder, the shoulder that is more forward and lower is likely to have a more winged scapula than the other side.
Consequences of Winged Scapula
A primary consequence would be a lack of range of motion within the shoulder, primarily in the actions of:

• Internal Rotation - 70+ degrees is ideal
• Adduction - 30+ degrees is ideal
• Extension - 60+ degrees is ideal

If these movements are missing, you'll be missing a lot of movement capabilities within your shoulder.
This winged scapula orientation also often results in a forward translation of the humerus (forward shoulder) within the Glenohumeral joint which often causes impingement and subsequent discomfort.
On the front side of the body, this causes the pecs and other muscles to become tight and compresses the front side of the ribcage on that side, preventing it from expanding and that can limit breathing mechanics.
This can also affect the elbow. If the humerus is in this internally-rotated position, the forearm could also be biased towards too much pronation.
Very similarly to how femoral internal rotation and tibial external rotation causes a knee valgus, the forearm can try to find supination it is lacking up turning "out" (relative to the humerus) and cause an "elbow valgus", which can heavily stress the elbow.
What Can Be Done To Correct Winged Scapula
The first and foremost priority that is most often overlooked is the ribcage.
If the ribcage isn't positioned well, neither will the scapula. Then the humerus won't be either and it feeds down the chain.
So we should start with the ribcage and position that first to allow room for the scapula to "roam" on the ribcage, then address scapular position. This is the step most people miss and why many don't get lasting results (in my opinion & experience).
Step #1: Expand the Ribcage - Rockback Lat Stretch
We should start with addressing the front side of the ribcage to allow for expansion to occur there. When we inhale, the shoulders should translate backward and the scapula should posteriorly & downwardly rotate.
This activity will help gravity act "downward" on us to allow for expansion to occur in the front ribcage while also releasing the lat, a muscle that is often contributing to pulling the shoulder and scapula forward.
You'll know you can get expansion in your ribcage anteriorly when you have passed the Humeral Internal Rotation, Adduction, and Extension measurements above.
Step #2: Re-Orient the Scapula - 90/90 Side Plank with Wall Press
After we can get expansion in the ribcage, we can then put the scapula in a better place. Two muscles that are very important for this are the low traps and long head of the triceps. Notice where the longer head of the triceps attaches. If it contracts, it will pull the scapula back.
Those are the two main steps that should be respected in that order. Those are just two exercises that can help in this situation, but is by no means a comprehensive approach.
If you are interested in a full approach, I'd encourage you to get a posture assessment done.

A bit about me for those of you curious...
I'm currently a third medical student (26M), living life one day at a time. I'm not the smartest student but I have a passion for helping in the community. I spent the first 2 years helping out with projects and volunteering as much as I could. 2 years later I'm still enjoying life. I go to school at a 4 year program, with a emphasis on clinical reasoning "learn what you need to be clinician with character" model.
What is Med like...?
It's hard, the article "101 things you wish before starting med" is true and its gets worse the further along you go. There are busy times especially during exam season. Flip side you learn so many cool and interesting things. Anatomy is hit or miss, those that love it the course wont go into enough depth, and those that don't it can feel overwhelming. Suturing cuts is a lot harder to do with a real person than on poultry. Suturing skill takes a long time to master compared to many other skills.
Each year of pre-med, med, residency, has its own challenges that you have to get through. It's always take it a day at a time.
Pre-med = "will you become a doctor?"
Med = "What kind of doctor will you become?"
Residency = "Where will you be a doctor?"
Overall, through medicine and even into first year residency (what's called a junior resident) you face so many "IDK WTF I'm doing..." moments over and over. But it all gets better with time, reminding yourself so many others made it through. Some of the coolest specialized doctors that have awesome skills were once in your shoes. Medical Students, Residents, and Doctors are great at masking their internal feelings really well.
What kind of doctor do you want to be?
OBGYN, I usually get heads turning because I'm a guy. I had an inkling before I started med, after I held my oldest sisters set of twins (her youngest ones). I explored my interest early on in med school and fell in love with it. Even after 2 years of school, I'm still super passionate about it. The most relaxed, peaceful, intimate births I ever saw were actually midwifery births. Having a midwife as a research supervisor she offered me the opportunity to be there for a few natural home births. Their isn't a right or wrong way with birthing practices as long as its a safe experience.
This question comes up a lot especially during your third year. Its usually asked like so "what do you want to do?", "what you want to be when you grow up?", "what are you interested in?", "What you want to do with your life?". Doctors and nurses ask about it way more than most lay-people unless they know a few doctors.
What are some cool memories.?
My most found memory was delivering my first baby as a first year medical student. I have since developed a passion for obstetrics. After delivering four more I found I enjoy that special emotional moment. Mom was a ER nurse that was having her first baby. I barely remember what I was doing during it because I was so nervous. After it was all done, I can remember the mom asking "How many babies have you delivered?......". The doctor looks at me and says "go ahead". The mom continues "Tell me I'm your first!".... I nod and say "Yeah".
After working a 24-hr shift with my doctor mentor. She drove me home after a long night. I still fondly remember the care she did in helping on that wet 8am morning. I always admire her ability to focus so much on personal growth. Her clinical practice has had such a positive influence on me as a future doctor (one day)!
One busy afternoon shift on the labor floor, there was no beds open, no assessment beds, with 6 women lined up in labor (waiting to be assessed). The staff were so overloaded, including my doctor mentor I was working with. I was tasked by my mentor to transport a woman (with twins) in labor to the ultrasound department. One catch she was a ruptured placenta previa! Basically the placenta is over the cervix and bleeds like crazy when the water breaks. The whole time I thought to myself 'I hope this woman doesn't die on me!'.
During the start of the pandemic I volunteered a lot with covid-testing. Granted I was in a high risk area testing a number of people, but it was thrilling. It was a rush to do the screening tests day after. I became an infectious disease fanatic during lockdown.
Any cool/amazing experiences in the hospital/clinic/etc...?
I did an optional experience in the NICU, where I toke care of a number of sick babies over a month. Day one the doctor I worked with, hit me with loads of questions around chest x-rays in newborns. I had no clue how to answer her. She walked me through afterward. Granted a harsh way to learn, but at the end I still know all the tubing placement really well.
During my same NICU experience, I got the opportunity to help out with a neonatal resuscitation. Oh man it was a emotional experience! Seeing this sick baby that was struggling to make it. I had a hard enough time being there, I couldn't image being the mother (who luckily wasn't in the same room). How could the doctors and nurses work in this field?
Once I went to assess a man with really bad prostate cancer to determine whether he could get surgery to cure him. It was an emotional interview, poor guy was almost crying the whole time. In the end he qualified for surgery which was relief. But its one I still look back on. He only learned he had aggressive prostate cancer 2 months before I he came to the clinic, had imaging, a biopsy.
I volunteered to help a 5th year resident with seeing patients in the hospital after surgery at 7am. He came 20 minutes late, which left me to see each patient on my own. One patient (whose surgery I was present for) suddenly had extreme pain just above his bladder. I'm there trying to figure out what's going on as a rookie. Documenting in the computer as I'm fumbling. I finally called the resident to come over and look him over. He comes takes a 30 second check, which involved touching his stomach area and hips. He asks the nurse to get an x-ray, and check his hydration every 2 hours! I told him I had to leave for a meeting in 20min. He approves and lets me leave. What a morning for things to crash!
My first trauma patient was a youngish woman that had appenditicitis. I thought she need surgery, but the residents and even the doctor supported just medications. It helped highlight that context is everything with medical/surgical treatment. There's general rules but still need to think every option.
My first call shift involved 26 hrs awake no sleep. It was the first time I experienced a patient yelling at me. A middle-age man came in with a painful hernia, came to the ER. I went to see him, asked him a bunch of questions and examined the hernia. Consulted the resident and got he set for an operation. He goes upstairs and gets crabby with the nurses asking "Why am I in the hospital?! What are you guys going to be doing?!!". A nurse calls and ask if I could talk with the patient about what's the plan moving forward. I go to see him and he yells at "I'm going to be having surgery?" As calmfully as I could told him "I see your upset, we're trying our best to help you, I'll let you know what were doing, than explain what's going on...". I elaborate "We need to do a hernia operation to prevent your small Intestine from getting caught inside the bowel. We just need to book space for your surgery right now... We are behind because we have 2-4 emergency operations tonight and 3 other minor surgeries to do yet."
My first day of orthopedic surgery was a hallux valgus osteotomy. It was surprising and shocking at the start because orthopods are violent with use of chisels, hammers, saws. I felt off for the first two but I managed to cope with the 3rd/4th one. The surgeon got me to suture during every procedure to as best as I could. Gave me feedback as I went along. At the end of the day the surgeon told me "You might want to practice your suturing when you can, try to look good when you get onto OBs rotation." - tba (Feb/mar 2021)
During Ortho, I got to spend the day with a new surgeon that just finished fellowship. He was working in the sports clinic elective OR on a really big tall man with a completely torn ACL. The surgery was to replace the ACL. The surgeon let the fellow start off the surgery with measuring the patellar tendon then removing a piece of it with some bone. The surgery did not go well, as the fellow removed too much tendon. The surgeon advised him to try to limit mistakes because the can really pile up. He also didn't remove enough bone to graft into the knee. To make matters worse the fellow instead of preparing the surface of the ACL for reconstruction. He completely destroyed the PCL (the good ligament) all while the surgeon was prepping the harvested ligament and bone removed from the patellar tendon. When the surgeon came in and realized the damage he had a difficult time holding himself together "he was that frustrated'! He told the fellow to leave the room which he did. He tried to fix the damage but unfortunately the PCL was too badly damaged to repair, so he bandaged the leg and transferred him to the nearby hospital. He contacted the fellowship director for a complaint and carried on with the rest of the OR slate (this is when Covid was starting to get bad). I didn't do much to help aside from suturing the ports and incisions. I felt bad for the patient, surgeon and even the fellow. It was all around mess to try and clean up.
On my single call shift during orthopedic surgery. I followed the resident to assess a 10-year-old boy that injured himself after falling off a swing. On X-ray of his arm it appeared broken and needed urgent surgery. When we went to see him, he looked uncomfortable and mom did not look very well either. I still recall seeing this subtle bruise on the elbow on the inside. His pulse was also faint as well. The resident started in on booking the OR while I documented the encounter. I wish I got to see that surgery but unfortunately I was stuck in the ER seeing another patient.
What do you do in your Free time?
Well I like to make reddit posts, have a bunch from an older account elsewhere. I learn and make cool memes.
I visit and talk with my mom a lot. She's fascinated by the many cool things that I experience and learn day after day. I still find her life story so amazing in many ways. She's lived a life unlike anyone I've ever heard.
I recently decided to improve my health through doing Yoga daily for 15-25 minutes a day. With lockdown in effect where I live, theres not option to live the house. On top of that I'm super busy with hospital shifts what free time do I have.
Describe your ideal job and work?
Well I'd ideally like a surgical practice. I love working with my hands and I love the intensity of surgery. I feel like I could be there all day there, doing procedure after procedure. I've sat a number of times at home in my free practicing suturing to get those skills down. Outpatient clinic is nice because it breaks the monotony and you get to understand your patient more than in the OR.
Where are you at with your clinical training? (... rotation)
Before I started in the hospital I have had clinical training in OBGYN, and Neonatal/perinatal medicine, and community walk-in Family Medicine. Other areas I've spent some time in (like a day) include urology, forensic pathology, infectious disease, oncologic surgery, nephrology, cardiology, Emergency. My clinic rotation experience is described elsewhere.
My current rotation is Anesthesiology.

Would You Rather Go 30 Days Without Your Phone Or Your Entire Life Without Dessert?

• Dessert, all those calories gone. I don't care about candy or dessert anyway. Its a sin in med school to order non-diet drinks. Bring a box of regular coke or Pepsi none takes it. Coke Zero, Diet Pepsi, diet ginger ale ONLY. lol
• Going 30 days w/o a phone is impossible in healthcare. I would need to have a 30-day vacation for that to be possible.

Would You Rather Be The Best Player On A Horrible Team Or The Worst Player On A Great Team?

• The latter = as a struggling stressed out med student, I related to the later case. One of the many medical doctor adage is "P stands for Physician". If your a real medical student you celebrate a passing score regardless of your 1st or 100th. Just don't be the one that fails it leaves you an emotional mess. Its one thing to celebrate the success of getting into med its a whole other experience celebrating graduation.

Who Or Where Would You Haunt If You Were A Ghost?

• The operating room would be nice. I could still watch surgeries without hassle. No anyone asking why am there. No risk of fainting from low blood sugar or from feeling overwhelmed. No need to worry about wearing scrubs.
• The catch: you wouldn't be able to help out with the surgery in any way. Which is the coolest part of the whole experience. Even holding the retractors or laparoscopic camera helped stay far more engaged.

Have You Ever Worn Clothing With The Labels/Tags Still Attached?

• A few times, the most embarrassing was leaving a sticker on my ass cheek.
• Scrubs have barcodes attached that

If You Got Stuck In An Elevator And Were Forced To Listen To Only One Song, What Would It Be?

• Taylor swift - shake off
• Please no Deaf Leppard, or Led Zeppelin. Literally every surgeon I've worked with so far listens to heavy metal all the time.

Who Would You Most Like To Sit Next To On A 10-Hour Flight And Why?

• Someone who will to talk for a good portion of the trip. Flying is almost inevitable as a healthcare provider, you do it enough times a year. Best to make the trips as nice as possible. Being able to talk and share personal stories through the flight makes time fly by faster.

last edit: 11-21-2020 ... 11-08-2020 ... 10-31-2020 ...

Hi, I'm 31 M programmer with 4 years of increasing/decreasing ulnar nerve symptoms in both hands such as 4-5 digit fingers pain/numbess/tingling, forearm tingling, hyperesthesia and pain near elbow, and shocking sensation over the ulnar with tricpes movements. Before the first pain started, I just started working my first programming job, so I was being on keyboards about 12 hours a day with work + gaming. I was also weight lifting. It started with elbow pain and shocking sensation with doing weighted dips and pushups. Then the pain and tingling started, and I stopped working out seriously, and playing video games. I did try multiple times to lift again, or play video games but it always got worse. I didn't try actually stopping everything - like off work and not touching keyboards at home.
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Left hand symptoms was always better then right hand, and currently there it's almost fully healed! Which gives me hope it can heal on itself.
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Right arm has gotten better over the years while I avoided using the triceps in weight lifting (basically quit) and stopped playing video games, but it seems to come back each time I try lifting again and use triceps movement too much. Even my current neck physio exercises aggravate it. My right elbow has minor cubitus valgus which might stress the nerve (or so I've read).
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I did multiple EMGs all showing no ulnar nerve involvement.
Did two MRIs, first one which I did a year an half ago, when my symptoms were much worse, showed neuritis of ulnar nerve and synovitis, I requested a second opinion on this and was told the imaging was of low quality, but it has signs of minor enlargement of the ulnar nerve (in a single slice near the cubital tunnel), no synovitis, and that triceps have a low belly that might explain compression on the nerve near the cubital tunnel.
Yesterday I repeated this elbow MRI scan at a better place (3T machine) and got new results from the second opinion radiologist from before (who also works there) - no ulnar nerve enlargement and no mention of the tricpes.
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Recently (~6 months) ulnar symptoms got better even though I started climbing and doing back exercises (no tricpes) in the gym trying to help my neck pain which seems from sitting all day this might correlate with the better MRI findings . But after a while I started getting all fingers (not just 4-5) joint pain which I used to have on and off since I started working but now came back again. Doctor suspects a rheumatology issue because of my multiple joints pain - elbow, neck, knee, fingers, and ankle. This doesn't feel related to the ulnar as it's all fingers and feels like overuse.
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Currently I'm off climbing for about 8 weeks now, and off work and keyboards for about 6 weeks because of the all-fingers pain and it didn't improve much. My ulnar symptoms are a lot better, mainly hyperesthesia near elbow after I do triceps movements physio exercises that I started for the neck pain which got worse after stopping climbing and corona sitting all day. I also sometimes get wrist ulnar sided pain.
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I was offered surgery before I re-did this MRI based on years of unresolved pain (doing PT, occupational therapy, splints), and I don't know if to do it, since I would like to lift, climb, and play video games unrestricted.... But recent EMG/MRI is all clear, and I didn't really try not doing anything - not even phisio and see if it will be better. I'm afraid it will get better and then come back again once I start working out/playing again as I imidiatly feel hyperesthesia once I do any triceps movements, so the low triceps belly causing this in the first MRI might have been correct.
Do you think I should do surgery for such minor symptoms? Should I just workout full force and see what happens? or should I make effort and be bored for months not touching any keyboards, excrecising, etc (really hard with corona and might lose job :/) and see if it resolves?
thank, blakeu88.

I work in an outpatient therapy clinic with an emphasis on sport performance. Has anyone had experience with a return to sport program after elbow UCL repair for wrestling specifically? Those that are familiar with wrestling, what common “moves” would put the most valgus stress on the elbow? What type of outpatient activities would you want to see your patient perform to feel comfortable with them beginning to return to wrestling activities? I want to look at both progression of exercise as well as functional movements that are wrestling specific.
On a broader level, where do you see the line between the role of therapy and a strength and conditioning coach? When is it no longer “medically necessary” and the role of the wrestling coach or other athletic professionals?

Edit: this post has updated information on exercise progressions and a better routine, it does not contain the theory section below though.
TL;DR: there are some underused exercises that can build the quads and hamstrings to advanced levels without added weight. The glutes and spinal erectors (lower back) are still probably too strong to make good gains past a certain level without extra load. I want to show you some possibilities and promote discussion.
THEORY:
(if not interested check out the next section about exercises including uncommon ones, or an example routine at the bottom)
The best exercises to build the lower body musculature and increase maximal strength are the ones that can be progressed gradually and without becoming unpractical or too easy past a certain point. The best candidates are the compound free weight lifts like squat and deadlift and glute bridge variations.
This post is to talk about the options for those who don't have access to a squat rack or a lot of weight, or who don't have access to equipment at all (working out at a park without people or rocks etc. to use at weight, people confined to a cell etc.).
If you can, use your dumbbells or create improvised weights like bags full of stuff, sand is probably the cheapest option that is space-efficient.
To increase load on muscles without resorting to added weight, we have to use leverage (changing body position so that the distance from a joint to the center mass of what it has to lift increases, requiring more force from the muscles to rotate that joint), unilaterality (forcing one side of the body to take partial or full load) and the muscle length-tension relationship (placing the muscle in more lengthened or contracted positions to require more force from it to create torque on a joint edit: the force required is the same but since the contractile protein of the muscles (inside their little "engines") is in a worse overlap compared to the resting length, the muscles will have to contract more often or more efficiently).
In squat variations, leverage is distributed between the hips and the knees depending on body lean and knee, hip and ankle angles. Since the center mass is under the midfoot when the heel is flat, here is how these angles affect the effort required from the hips and knees. This applies to single leg squats too, as I'll explain later.
Exercises can be made partially unilateral (lunges, split squats, side to side/Cossack squats etc.) or fully unilateral (pistol, shrimp, deep step up, single leg hinge exercises etc.). Unilaterality can introduce a big stability challenge, mostly due to weakness in the gluteus medius (outer glute, stabilizes the hip orientation) and the intrinsic foot muscles (they create the foot's arch/tripod position, which makes the foot and ankle stable). This instability can also be present in bilateral exercises and it puts the knee joint in a bad alignment (the optimal one is knee parallel to the middle toes), causing knee stress and pain with time.
A solution can be holding an object for balance assistance while doing an unilateral exercise until you improve your stability.
The other challenge is mobility. The most common limitation is ankle dorsiflexion, the ability to close the angle of the shin and the foot, which makes the knee travel forward and prevents you from falling on your ass in any deep squat exercise. This can be corrected with bent knee calf stretches or compensated with heel elevation through a ramp or a wedge or weightlifting shoes etc.
Some individuals will never be able to achieve a flat footed deep single leg squat without heel elevation if their anatomy (short torso, long femur, short tibia) or anterior ankle impingement (sometimes treatable, sometimes not) is the problem.
Another possible limitation is glute inflexibility if you can't bring the knee to your chest, or in bilateral squats adductor inflexibility, which prevents you from pushing your knees out for proper knee tracking if your stance is wide. These limitations can be addressed with mobility work, but your hip socket anatomy may prevent you from reaching full depth in some stances.
A lack of mobility can cause ankle overpronation as a compensation (losing the foot's arch to gain some ankle range of motion), which puts stress on the knee, or back rounding (also known as butt wink) as the torso bends forward to create a counterweight. Repeated flexion of the lumbar spine under load, or even with bodyweight load if for very high volume, can damage the spine over time. In pistol squats, hamstring inflexibility of the free leg can cause back rounding too (because posterior pelvic tilt makes up for hip flexion), but just by standing on an elevated surface and letting the free leg drop this can be solved.
Having addressed these challenges, leg exercises can be classified depending on where in their range of motion the hardest point is.
Stretch exercises are those where the muscles have to overcome a significant lever arm while lengthened. For example in deep squats the glutes and quads are stretched at the bottom so they are weaker, that is why the sticking point of a squat is in coming out of the hole.
Contraction exercises are those where the hardest point is near the muscle's full flexion point. This also reduces the tension a muscle can produce according to the strength curve.
These two exercise types together load the muscles through a full range of motion.
Edit: note that strength is quite specific to the ranges of motion trained, so if you are not a soccer player or martial artist or rock climber etc., the end range of stretch exercises may carry over less to your activities.
EXERCISES:
If you only have your bodyweight and maybe a small amount of extra weight, to make good use of it you'll have to "divide and conquer" the lower body, since together its mass is too strong to be challenged after a certain point. So these exercises are classified depending on which is the primary muscle worked, but some variations are quite balanced and will also work the other muscles, while other variations mostly isolate one muscle.
The most measurable progression methods are probably range of motion and leverage.
Quadriceps:
Here the main factor that increases difficulty is how far forward the knees travel over the toes, since it increases the lever arm on the joint. This is not necessarily bad and the old myth about not allowing the knees to pass the toes is bullshit, but when they travel forward a lot you may need time to strengthen the tissues gradually, just like the elbows in muscle ups. If you already have significant knee problems you may need to limit the amount of travel you allow. Also remember that proper knee tracking (knees aligned with toes) is still necessary to prevent knee valgus pain.
Stretch exercises:

• Deep single leg squats have your quads and glutes stretched at the bottom. So pistols, foot elevated shrimps and deep step ups. To make them more quad dominant, eliminate the possible forms of counteweight: tuck the free leg (tuck squats) or even bring it behind your body (shrimp squats, deep step ups), put the arms on your chest or behind you (for example advanced shrimps where one or both hold the free foot), keep the torso more upright. If ankle mobility limits you, use a counterweight (also good for allowing a neutral spine) or elevate your heel on an object or by staying on your toes (the second option may be worse because it's harder to balance).
• Sissy squats, where you stay on your toes and let your knees travel forward as much as comfortable. A wall may be used to regulate knee forward travel. There is a partially unilateral variation but I haven't seen anyone do them fully single leg. It may be possible but awkward to balance and to maintain knee tracking. These can be made harder by allowing less hip hinge, this will put more stretch on the quads. A single leg sissy with zero hinge is theoretically the hardest possible quad stretch exercise.
• Kneeling leg extensions, which put a lot of stretch on the quads. Depth is a progression method and keeping the arms to the sides or behind you increases the lever arm. No hip hinge makes this harder. A single leg version would be even harder but it doesn't look practical.
• Ultimate quad stretch exercise: elevated advanced shrimp squat with heel lift. A single leg kneeling extension or sissy squat with no hinge may be harder but I haven't seen it done. If you have access to some weights, pistols on an elevated surface (so the free leg can stay lower) and a counterweight (or heel elevation) are the most mobility-simplified full range exercise.

Contraction exercises:

• Anchored leg extension: this is not very practical to set up, except if you stay closer to the ground, I have done it with a park bench but it may break. Here the difficulty can be scaled with the amount of hip hinge and by extending the arms behind. The top part is the hardest because you are fully extended perpendicular to gravity. If a single leg version of this can be done, it would be the hardest quad exercise possible.
• Knee extension from plank: can also be done double leg. I have tried this a few times and after 10 reps I felt a nice quad burn. Not sure if it's very healthy long term, I haven't tried it much and it requires accurate knee tracking.
• Ultimate quad contraction exercise: If it is possible, a single leg anchored extension with straight body from knees to head and arms behind you. The knee extension from plank can be done with zero equipment though. Honestly I don't think you actually need a quad contraction exercise at all.

Glutes:
Stretch exercises:

• Single leg squats where you lean forward a lot with your torso and extend your arms forward will allow you to sit back more and the knee will not travel forward much, so the hip lever arm will be longer and it's easy to get full hip flexion even without a lot of ankle mobility. Here hamstring mobility may limit you and you need good knee tracking. Pistol squats when you barely have the ankle mobility will tend to be this kind of exercise, but quite balanced between glutes and quads. The glute dominant variation is the single leg deadlift, unfortunately without weight it quickly loses its challenge.

Contraction exercises:

• Glute bridges are the best example of this. To do them right and reduce hamstring assistance, you need full hip extension and posterior pelvic tilt at the top with a vertical shin. These can be made harder with a single leg and by elevating the shoulders (hip thrust) and optionally the feet too. Elevation increases the range of motion and makes the body horizontal at lock out, so you are perpendicular to gravity and the load is maximized. Unfortunately even the elevated single leg version won't last very long. But it's a good exercise to load with extra weight. At home some pillows may be needed to cushion the hips from the pressure of added load. iAznN00b has suggested doing these on progressively longer ring straps to increase the difficulty just like ring pushing is harder, but I don't have experience with this. Example on rings.

As a bonus, glute bridges done properly can gradually correct anterior pelvic tilt.
So you can see that the glutes, being one of the strongest and biggest muscles in the body (only the lats can rival them), quickly get too strong for bodyweight only.
Hamstrings:
Here I don't think there is much need to separate them into contraction and stretch categories, since the quad and glute dominant exercises give them some stimulus, and one hamstring dominant exercise can be enough. With bodyweight you may never run out of challenge, as you'll see below.

• Glute bridges with a straighter leg or less posterior pelvic tilt: if your shin is horizontal at the top and you don't engage the glutes by tilting the pelvis, you will feel these mostly in the hamstrings.
• Sliding or suspended hamstring curls: with one or two legs, you can use a furniture slider or socks on a smooth surface or rings or trx straps. The floor single leg version is quite challenging and easy to load with some weight or more friction. Maintaining full hip extension makes them harder. Here is an example of single leg with more friction. This is the most available hamstring exercise, just needs somewhere to slide or suspend yourself. Can also be done on a stability ball.
• Glute ham raise and Nordic curl (aka Russian curl, natural hamstring curl, Harop curl): if you can anchor yourself under something this is the ultimate progression. The easiest version is just a hip hinge while the hardest is arms forward and no hip hinge. I have written a detailed post on this exercise 's progressions and where to do it here.
• If you have inversion boots, you can do upside down squats. I haven't seen a single leg version, it may be the most challenging version. Also if you hinge less and extend your arms it should be harder. I haven't seen this either.

Sliding curls are the most available choice, Nordic curls are a bit harder to set up but amazing. The ultimate hamstring exercise is probably the single leg Nordic curl or the single leg inverted squat with no hinge, but I'm not sure one can ever become strong enough. Here's 16 strict Nordic curls with two legs for reference. A rare display of relative strength.
Edit: if you have a decline bench, this version of the GHR or Nordic curl is harder than on a horizontal surface.
Lower back/spinal erectors:
Here you either train back extension dynamically with extensions or reverse hyperextensions, or statically with shoulder reverse planks. All of these exercises soon become easy, here's a guy bridging with 210lbs/95kg. Adding weight will be worthwhile.
Edit: in this comment there are more ideas: back lever reverse hyper, suspension or rings hyperextension and reverse hypers with less of the body supported (no video example and it may be dangerous for the spine).
Back levers and planches and press handstands also require back strength but nowhere near heavy squats and deadlifts or these isolation exercises. However gymnasts can often do well on their first squat and deadlift without previous direct training (example), but keep in mind that the landings from tumbling are like heavy eccentric deadlifts, so your average street workout athlete won't have the same experience.
Finding a place for reverse hypers is simple, here's a good video by fitnessfaqs.
Calves:
There are two muscles, soleus and gastrocnemius. The former is strong with straight knees and the latter with bent knees. To train these do calf raises with one or two legs, preferably on a stair you you can get full range of motion with a slow eccentric and a pause at the bottom, or you'll just use the elastic energy of the Achilles tendon. If you have short muscle bellies you probably won't grow much, while if you have good calf genetics you'll grow well even with low loads if you do high volume. Also just doing sports, running, jump roping etc. can grow the calves.
Adductors and abductors:
These are mostly trained for stability and compound movements will already stimulate them, especially single leg ones. Here are some isolation exercises if you want.
CONCLUSION:
So we've seen that the quad and hamstring bodyweight potential is underrated, while the glutes and lower back can be trained to an intermediate strength level but after that it will be mostly endurance. The calves depend on genetics and high volume of low intensity can work to grow them.
How do we squeeze the most out of an easy exercise for muscle growth?
If there are no harder variations to train, we can increase the total volume (more sets), frequency (more training sessions) and density (less rest) and always go to failure or close so all the muscle motor units still get recruited, or do rest-pause training. It may work for hypertrophy (and as a consequence slightly increase maximal strength) but it will be less energy and time efficient than adding weight. An example of high volume guys with big legs are cyclists, especially those who often go uphill.
We can also shift to training explosiveness, with sprinting or plyometrics, but this will mostly let us express our already existing strength potential (based on maximal strength), and the volume needed for hypertrophy may cause injuries. It can help though, like for gymnasts who deadlift heavy thanks to tumbling.
EXAMPLE ROUTINE (1-3 times a week):
If some weights are available (all exercises are weighted, rep range can be 3-15 or inbetween):

• 3-5 sets Bulgarian split squats or single leg squats (if hamstrings are tight, stand on an elevated surface, if calves are tight use an elevated heel or counterweight).
• 3-5 sets single leg hip thrusts or single leg deadlifts.
• 3-5 sets hyperextensions or back extensions or reverse shoulder plank (10-30 second hold).
• Optional: 1-5 sets of hamstring isolation exercise (suspended,sliding or Nordic).

If no weights are available (rep range 3-15 or inbetween, when you max out use a harder exercise, if none are available you can do even more reps or sets if time allows):

• 3-5 sets quad dominant progression: if you can't do single leg squats, do partial range until you can. Else elevate the heel or use more ankle mobilty so that your knee travels more forward, or reduce hip hinge. Or do a sissy squat progression (can use wall to limit range of motion). Or kneeling/anchored/plank leg extensions.
• 3-5 sets single leg hip thrust progression (can use this one).
• 1-5 sets of hamstring isolation (example progression).
• 3 or more sets of hypers or back extensions to failure or close, some reverse shoulder planks if you want. And if you can do the planche or back lever without much tuck, that can replace or supplement lower back work.

Optional: calf work, plyometrics, sprinting etc.. Explosive or high intensity interval training should count as a leg workout for recovery purposes.

THIS POST IS OUTDATED, HERE IS THE NEW VERSION.
Here is the list of the leg exercises requiring the most strength, a few of them also require balance and mobility. For the exercises where I could not find a video I've drawn some images to give an idea of what they would look like. If you have seen something harder or can record it yourself, please post a link. Or feel free to share your experience with hard bodyweight exercises even if they are easier than the ones here or ideas for new leg elements.
If you have a squat rack available you don't need most of these, and with limited weight, even improvised (sandbags are cheap, construction guide by Ross Enamait) you can do weighted single leg exercises (pistol squat, skater squat, split squat, deep step up, hip thrust, Romanian deadlift etc.), and Nordic curls are still useful in any routine, even if you have barbells.
The following exercises are hard even with no added weight but of course you can do them weighted if you want.
Update: Any exercises unlocked after this post was submitted are marked as "new". Stefano Ravarino was inspired by this article and has made a video demonstrating many leg exercises, from beginner to the hardest unlocked so far and also has good illustrations of the unreached versions too. Video link.
THINGS TO BE CAREFUL ABOUT.

• Proper knee tracking, especially in single leg variations. The knee should face the direction of the middle toes, if it collapses inside (knee valgus, another article) there is a lot of stress on the medial collateral ligament. Not to be confused with how far forward the knee travels over the toes, which is not a problem. Improving strength in the outer glute (gluteus medius), strengthening the foot's arch and increasing ankle mobility (to avoid compensations with pronation where the weight is too much on the inside of the foot, causing the loss of the arch and valgus) make the knee more stable, and support from the free leg (like in Bulgarian split squats and maximally deep step ups) or the hands can be used to reduce the stability requirement.
• Knee shearing forces. For the straight body quad exercises they are higher, but if you have healthy knees and anterior cruciate ligaments and limit volume and intensity until you adapt and can do more without discomfort, it's fine. Article by Brad Schoenfeld, related advice by Joshua Naterman. It's similar to shearing stress on the elbows in muscle ups, people build up progressively to levels like a +45kg/100lbs ring muscle up at 65kg/143lbs bodyweight. That's +70% BW!
• Enough padding for the knees and the feet where they are anchored in Nordic curls, so that the kneecaps can move freely, and for the calves in strap leg extensions, and using stable and robust places to anchor yourself, you need an anchor point that can support hundreds of pounds/kilograms.

NATURAL ONE LEG PRESS.
Challenges quads and glutes through a full range of motion. This looks deceptively easy but depending on the friction of the surface you use, it can be as hard as a pistol squat with 40% bodyweight on a wooden door with a towel, or 75% bodyweight in the video, even more if there is more friction. Video, post with discussion, Naterman's safety advice. I have tried doing it at the park against a metal pole and it can work too, it's just harder to balance with less surface. There were already videos of this exercise on two legs with a skateboard or single leg with a stability ball, but those are regressions and the concept of doing this while maximizing friction is new so there is still a lot of research to be done about this exercise.
New: deficit natural one leg press, even more strength required and even more dangerous if you try this despite knee problems. The hardest leg exercise currently unlocked, at least when done on that surface with high friction.
FREESTANDING QUAD ISOLATION.
Advanced shrimp squat.
Intentionally done on the toes, the center mass will be over them and the more the knee travels forward, the longer the lever arm on the knee. The hardest version is the Ido Portal shrimp. Both arms behind, hip of the free leg as straight as possible, a deficit for full knee flexion. The glute does some work too but not a lot since the lever arm on it is short. More balance than pistols is required but a lot less than free handstand pushups, which are used by people for working sets for strength and size, as shown by Jonathan Ferland-Valois/wandererstraining and LittleBeastM/Metin Dabak.

• Exact demonstration of Ido's version. The only difference is that Ido supposedly starts from the bottom to eliminate the stretch reflex.
• More demonstrations of Ido's form, the guy who did them says he found this version more difficult because of having to reset the tension when the knee rests on a surface at the bottom.
• 9 reps with the help of the stretch reflex and having the wall by the side instead of behind, so slightly easier.
• All three of these guys can squat around 2x bodyweight. I can do a pistol squat with +50% BW but can only do a slow negative of the two hand floor shrimp with no deficit, which is easier, so the advanced shrimp is quite challenging and this explains why there are so few deficit two hand shrimp videos on youtube.
• New: 5 elevated repetitions with the wall in front and not by the side. Best performance I've seen for now.
• New: very quad dominant one leg squat (after the elevated two hand shrimps). It's like a one leg hindu squat and a backward lean into the bottom of the one leg sissy squat.

Single leg sissy squats and kneeling leg extensions.
These, done single leg and with a straight body, with arms overhead if possible (unless it shifts the weight too much behind the center mass, causing you to fall back), would be much harder than the Ido shrimp. I have not seen videos of the real deal so here are some illustrations of how they could look like. Update: kneeling single leg extension now exists! Some variations:

• Super deep two leg sissy.
• New: (actually a very old video) absurd sissy squat, with a lot of hip internal rotation too, I've never seen anything like this, it also requires a lot of spine mobility, I don't know if others have done this.
• Super deep kneeling leg extension, arms overhead for the longest lever arm. An assisted single leg version similar to the sissy or a real single leg one with the free leg off the ground like a pistol squat could be possible.
• New: kneeling one leg extension with slight balance assist.
• Assisted one leg sissy. Not easier to balance than unassisted, but requires a lot less strength.
• New: one leg sissy with some wall assist, partial range.
• New: door frame assisted concentric and fully elevated negative, trying to assist with the upper body as little as possible. Can also be done with dip bars or similar parallel supports, here is a heavily weighted (60kg/132lbs) elevated concentric with some hip bend, it's possible that by squeezing the support hard the arms can assist noticeably.
• New: unassisted one leg sissy partial concentric and full negative. Note: Naterman told me this is a very dangerous movement and he would not recommend this to anyone. So I guess the wall assisted version above is much better, if you try it freestanding it's at your own risk.
• New: unassisted full negative and bent hips concentric, and another guy who is equally close to a clean repetition. Two different ways of positioning the free leg.
• New: Kneeling one leg extension. Hardest quad element currently unlocked, harder than the natural one leg press according to Matteo Spinazzola. Although the elevated one leg press on a rough surface is harder than this, but it's a compound movement.
• New: one leg sissy squat from horizontal shin position, 3 reps from mat, one rep with no support at the bottom. Maybe harder than the one leg extension, and still not a full range one leg sissy squat. I'm not sure the second video is not a reversed recording of an eccentric.

NEW: friction resisted sissy squats.
From this comment by u/Jack_n_coke. Video demonstration and thread with form cues and other advice
Very practical since you can reasonably get maximum knee flexion without balance or mobility being a problem. With smooth wood it may be easier than freestanding sissy squats, but on less smooth surfaces it can be harder.
And the one leg version seems to be doable, the wall helps with knee stability.
STRAIGHT BODY HAMSTRING CURLS.
If we have the hefesto for the biceps, these are the counterpart for the "lower body biceps".
A relatively easy variation worth mentioning: suspended single leg hamstring body curls.
With inversion boots.

• Inversion/gravity boot squats, these are a hamstring curl actually and the two leg version is not super hard, but imagine doing it with a straight body (by fully extending the hips), it would be like an upside down version of the Nordic curl. Or single leg, and the theoretically hardest version would be single leg, straight body, arms overhead. I have illustrated the theoretical harder variations here.
• New: leg human flag curl, not very practical but challenging and creative.
• New: one leg inverted pistol squats to 90° knee. Compared to the link below, the range is slightly less, but no support from a hand holding a pole, and maybe less ergonomical because of the improvised alternative to inversion boots.
• New: one leg inversion boot squats, with a hand holding the pole for stability, not full range but close.
• New: inverted Nordic curl, on stall bars with inversion boots (the link above, a few seconds later), partial range of motion.
• New: inverted Nordic curls to 90° knee, with door anchor and stall bars, the latter setup is safer and does not require a partner attaching the carabinier.
• The straight body inverted one leg Nordic curl with a full range of motion (hamstring touching the calf) could be the hardest hamstring exercise ever.

Nordic curls.
The normal two legs ones are already quite hard, but these are even harder:

• Arms overhead for a longer lever arm.
• On decline bench to get a longer arc under load. You can add more and more decline until you do inverted Nordic curls.
• Crossed legs, Matteo Spinazzola says one rep feels like a normal Nordic curl with +25-30% BW.
• New: one leg Nordic curl with some hip bend during the ascent, another guy.
• New: One leg and the other knee not supported. Quite good form!
• New: 13 repetitions with reasonably good form, still not perfect but the greatest display of bodyweight hamstring strength I've seen for now.
• A single leg decline version with a straight body and arms overhead would be the hardest version, here is an illustration.

STRAIGHT BODY ANCHORED QUAD EXTENSIONS.
We have impossible dips and impossible tiger bends for the triceps, and the quads are like the lower body triceps.
Vertical shin leg extensions.
Often done on an apparatus called sissy squat machine/bench/Roman chair squat, or quad blaster. A fitting name would be Matrix squats or Neo squats since they resemble Neo's movement in the famous bullet dodge scene. Can be done against a pole with the feet pressing into it to avoid sliding.

• Variation in sand, worth mentioning since without this video I would not have learned about this exercise. Even unweighted it's harder than pistol squats.
• Arms overhead descending to parallel, this is the hardest possible leverage on two legs but more range of motion would make it harder.
• Progression steps ending with the arms overhead to parallel version. Also showing one of the simplest setups for this exercise.
• Extra range of motion on the sissy squat bench. Significantly more knee flexion but slight hip bend.
• New: the highest range of motion achievable on the floor. Had to link myself again since I could not find anything similar on youtube, it feels as hard as a pistol squat with +40% bodyweight.
• New: Maximum range of motion on two legs, the calf touches the hamstring at the bottom, extending the arms overhead would make it even harder.
• Proof of concept for an assisted single leg version. Only one leg is fixed, the other could be kept as straight as possible and slide during the movement to only provide stability against knee valgus without contributing much in strength. This image explains the problem with true single leg matrix squats. You'd need to lean/bend the torso to the side to balance yourself. Update: you can avoid this problem without twisting to the side but you still need some lean and a lot of caution to avoid knee damage.
• Illustrations of the missing variations: super deep two legs, assisted single leg, real single leg here.
• New: shrimp quad blaster. Basically a tucked Matrix squat with the knee touching the floor at the bottom. A big difficulty is resetting the body tension to lift off after the knee is on the floor. Not necessarily a safe/practical variation compared to normal Matrix squats, but creative and hard.
• New: true one leg to parallel. Much better form than I expected to be possible, requires very good bracing with the strap and toes bent and solidly in contact with a wall.
• New: one leg to parallel with arms overhead. This pipe setup provides good support making it not so awkward to balance, further knee flexion is not possible but this is a notable level.
• New: one leg to parallel, 3 reps. Another stable setup, with a bench. Some hip bend but a good achievement.

Horizontal shin leg extensions. (a possible name is leg extension lever)

• Full range of motion, the top part can also be done on a park bench, or by fixing the legs to some bench with a strap. Could be made harder with a pause at the top, arms overhead, assisted single leg (only one leg held down or fixed with a strap), true single leg.
• For the park bench and strap true single leg version, here is an illustration.
• New: using monkey bars as an anchor point.
• New: good form with a bench and a doorframe telescopic pullup bar. Arms overhead extends the lever. The version shown by the gymnast is harder if a pause at the top is made, since the body is always kept straight, but it needs a high surface to give the body space.
• New: one leg version, slightly bent body. According to the person executing it knee twisting is not a problem, in contrast to the one leg Matrix squat. Straight spine and arms overhead would be harder.

OTHER INTERESTING STUFF.

• For the straight body quad and hamstring variations, you can change the incline to modify the challenging arc, here is an illustration of the concept.
• Cool mobility stuff by Jon Yuen. Not really more challenging for the quads and glutes compared to pistols and sissy squats, but active mobility at end range is also a form of strength.

CONCLUSION.
The ultimate theoretical exercises requiring zero weights are these:

• For quad isolation, the real single leg version of the sissy squat, kneeling leg extension, vertical shin (Matrix squat) or horizontal shin leg extension (leg extension lever) with no support from the free leg, straight body, arms overhead for the longest lever arm and using the maximum ROM possible. An assisted single leg version with the free leg providing balance is probably much more practical and safe, but the one leg extension lever has been shown to be practical since there are no knee twisting problems, only the need for well conditioned knee tendons.
• For hamstring isolation, real single leg decline or inverted Nordic curl. Straight body, arms overhead, maximum knee flexion at the top.
• For compound glutes and quads, the deficit natural one leg press with a very high friction surface. Shoulders and feet elevated single leg hip thrusts are the hardest glute isolation I know of, but it's not very challenging since the glutes are often the biggest and strongest muscle of the body. Maybe also glute bridges against an immovable resistance.
• For calves: for the gastrocnemius Nordic curls with plantarflexed ankles (straight) since the gastroc is also a knee flexor, or deep single leg calf raises without bouncing (no stretch reflex), maybe straight leg calf jumps on one foot, for the soleus single leg calf raises or jumps at the bottom of a squat. But you can just do sports, rope skipping etc. and the calves will grow.
• For the shins (tibialis): shin raises with a wall, done with the feet far from it and on one leg.
• Adductors and abductors: unsupported side splits and the stuff from here. For adductors sliding from splits to standing.
• Spinal erectors: reverse hyperextensions, (the back lever or back lever leg lifts are not actually more challenging for the lower back, only for the upper body), but for endless resistance isometric deadlifts or good mornings against something immovable like a rope or towel or bedsheet etc.

An interesting addition to a true minimalist routine could be ring deadlift isometrics, with wrist straps to eliminate grip limitations, with these you could also potentially challenge the spinal erectors long term. Or just a strap for squats and deadlifts and good mornings etc.
Relevant stuff: Ross Enamait's isometric tool and training with resistance bands, which is similar because the tension is maximized in a narrow range of motion.
Explosive training, like jumping single leg squats, broad and high jumps, sprinting etc. are also useful to periodize/integrate in a leg routine, thanks u/ImmodestPolitician for the suggestion.
I think minimalist leg training has undiscovered potential. Update: ideas for combining these different approaches.
Other useful links:

• Complete guide to Nordic curl setups and progressions.
• Guide to the matrix squats with straps.
• Minimalist setup for Nordic curls and matrix squats using a wooden board and one or two straps.
• Somewhat outdated analysis of leg exercises and possible minimalist routines. At the time I did not know of the natural one leg press and many of the hardest variations had not been done.

I had the pleasure of sitting down with a respected PRP Doctor in LA and talk about PRP, Lonzo's procedure, and what it means going forward.
For reference, I'm a DPT.
For a TL;DR, read the section after the last image link.
PRP to BBB: Q&A with a PRP Doctor re: Lonzo's PRP Procedure
Recently, we found out about a Lonzo PRP procedure on his left knee which kept him from participating in full basketball activities for a month afterwards.
This Lonzo PRP procedure was likely stemming from the two left knee injuries he suffered during the 2017-18 Lakers season. He missed a little over 5 weeks due to a grade I MCL tear (all sprains are tears, don't let that word scare you) and missed the last 8 games of the season with a "lateral knee contusion", almost certainly a bone bruise.
The latter occurred when Lonzo was holding up Dirk on a screen and came away limping afterwards:
https://i.imgur.com/33LzvtA.gif
There's no clean shot of the contact point with Julius blocking our view. However, what's key to note is that this seemingly innocuous play resulted in an injury. It's an indicator that informs the rationale behind why the Lonzo PRP procedure was done (much more on that below).
The focus of this piece is on PRP and the Lonzo PRP procedure. I had the good fortune of sitting down with and picking the brain of Dr. Shounuck Patel, DO who is a trusted PRP practitioner, running the Health Link Medical Center in Beverly Hills, CA.
With his expertise and interjections, we’ll answer the following questions:

• What is PRP? What is it used for? Are there different types?
• The Lonzo PRP procedure was most likely which type?
• What's the rationale behind the Lonzo PRP procedure?
• What are the risks and benefits of the Lonzo PRP procedure?
• Why did Lonzo need to take a month-long break from full basketball activities?
• Are there any short or long-term implications from the Lonzo PRP procedure?

Without further ado, let's get right into it...
Me (RB): Lets start with the basics. What is PRP?
Dr. Shounuck Patel, DO, (SP): PRP stands for "platelet-rich plasma". It's a procedure that harnesses your body's natural healing factors to aide in restoration and repair. It's done by extracting the person's own blood and then concentrating the platelets that contain healing growth factors.
Most PRP providers use a simple automated centrifuge for this separation but we have a lab and skilled technicians that results in a more customizable PRP mix that is tailored for each specific patient’s problem.
For example, most centrifuges concentrate the platelets by a factor of 2 to 7 times baseline, but our Regenexx process increases that factor by 6 to 40 times baseline. Since we've found that different concentrations are better for different tissues, we find better results with this ability to customize.
RB: I'll get to the details of the injection procedure itself in a second but first, lets talk about platelets. I know they cause your blood to clot (for example when you have a cut and the blood stops) but I'm assuming there's more than meets the eye? (Insert Transformers reference)
SP: A lot more than meets the eye. Platelets play a key role in the body's healing process by releasing growth and healing factors at the site of an injury (referred to as a "healing cascade").
Here's a picture (don't worry about the details, just appreciate the extent of growth factors):
https://imgur.com/RgkfEfp
SP: Further, they create an inflammatory response (the first part of the healing process) that calls stem and other cells integral to repair into the area. After the process has run its course, the platelets then signal for inflammation to subside.
RB: To clarify, because I get this question and have to explain it a lot, inflammation isn't bad.
SP: No, it's not - it's a key part of the body's healing process. That being said, it can be very painful and hinder movement when excessive in the acute (immediate) phase following an injury and certainly also if inflammation lingers for a longer time. The beauty of PRP is that we can harness and dose the inflammation response appropriately, and when done right, precisely target the affected area for optimal affect.
RB: "Precisely target the affected" area, tell me more.
SP: With PRP injections, precision and technique matters a lot. The more targeted your injection is, the more optimal the effect with better outcomes. In order to achieve that level of precision, I'm using image-guidance (like Ultrasound for example) during my procedures to know exactly where I'm injecting. Otherwise, it's almost like you're flying blind to an extent.
RB: I've seen some of your image-guided injection videos online. Readers, here's an example of an injection into the hand:
https://www.youtube.com/watch?v=CmmsbNE0mck
RB: From my understanding, image-guided targeted injection is the backbone of an emerging paradigm known as interventional orthopedics. Tell us more about that.
SP: Interventional orthopedics is the intersection of osteopathic, physiatric, and regenerative medicine. Viewing the body as a unit where structure and function are interrelated and utilizing the body's self-healing abilities and processes to repair damaged tissue and restore maximal function, all via non-surgical interventions.
Here's a visual from a presentation I gave which shows where interventional orthopedics slots in - focus on the bottom part:
https://imgur.com/zNJLZ0G
SP: In order to maximize the efficiency, efficacy, and outcomes of these non-surgical interventions, we use image guided precision injections to precise targets in order to change mechanics, induce healing, and optimize the movement.
RB: Does everyone utilize the principles of interventional orthopedics and image guided precision in their PRP procedures?
SP: Unfortunately no. As tends to happen when something becomes popularized and more into the public eye, PRP is being marketed and used by more providers who are legally allowed to penetrate a joint with an instrument (such as surgeons, nurse practitioners, and in certain states naturopathic doctors).
Many of these providers are injecting PRP without image-guidance as if it is a simple cortisone injection rather than purposefully targeting specific tissues. Without image-aided procedures, it's really difficult to be precise with your targeting.
RB: So it's almost like a shotgun blast hoping to hit the right spot compared to the sniper shot of interventional orthopedics. It's similar to what we've talked about in other conversations about the importance of precise manual diagnostics and musculoskeletal assessment.
SP: Exactly.
RB: What's the difference between interventional orthopedics and surgery?
SP: Surgery is also targeted but it's invasive – even with the most “minimally invasive” surgeries, you're still physically opening the person up which comes with longer recovery times, inherent risks of infection and scar tissue, and irreversible changes to structure, not to mention having to undergo anesthesia which comes with its own recovery and risk implications (and, of course, added cost).
RB: Here's the analogy I thought of to compare surgery vs image-guided PRP (part of interventional orthopedics). Lets say your car's alternator was having problems and needed to be replaced. Surgery would be like ripping open the hood and then delving through the parts to find it and fix it or replace it. On the other hand, image-guided PRP would be like using imaging to see through the hood, threading an instrument to precisely find the alternator without interrupting any other parts, and injecting it with a self-repair serum.
SP: It's a rough one but yeh, I'll allow it. To finish that off, we could say that non-guided PRP approach is like threading that instrument and then showering the general area with that self-repair serum....hoping it hits the target.
RB: Boom, advance to go and collect 200 platelets. Alright, so we've talked about the basic rationale behind PRP, but now lets talk about some of the nuances. Are there different types?
SP: For the sake of the audience, I'll keep it really short and simple. There are two types of PRP that we create in my clinic.

1. Our Regenexx-SCP (Super Concentrated Platelets) is an advanced form of PRP that can be customized for different conditions and made to a higher concentration as I mentioned above.
2. We also make a different category of platelet solution called platelet lysate (PL) which results in a very fast release of growth factors producing a net anti-inflammatory effect. However, it's a rare procedure because it's specialized and requires a certain type of laboratory to create PL. At Health Link Regenexx, we do have access to the required equipment and there's emerging evidence of its benefit with nerve injuries and muscle re-growth.

RB: Got it, PL is pretty rare so we'll leave that alone for now. What about stem cell injections?
SP: Stem cell injections introduce new stem cells capable of healing AND activate stem cells that have gone dormant (stem cells are living throughout our body at all times).
Here's a basic overview of the process:
https://imgur.com/tF9n1sz
RB: When is a stem cell injection indicated vs PRP?
SP: Stem cells are indicated for long-standing issues like severe arthritis or more significant injuries like ACL or other soft tissue tears, whereas PRP is indicated for milder arthritis or recurrent or lingering soft tissue issues, like tendons strains or ligament sprains.
PRP can be used to "jump-start" or "re-start" a stalled healing process. Common procedures include lateral or medial epicondylosis (tennis or golfers elbow), hamstring injuries, and numerous other conditions including MCL injuries.
RB: That's a perfect segway into the Lonzo PRP procedure (almost like we planned that out or something). Based on your experience with his type of injuries, what do you think was the impetus for the PRP procedure? Obviously we'll never know because we didn't treat him directly, but what's the most logical inference?
SP: Lonzo's injury history and mechanism of injury with his bone bruise give us good indicators of what's going on.
The first thing is the MCL grade I tear. A grade I ligament tear can actually linger longer than a grade II tear because the body doesn't take it as seriously, there's not an "all hands on deck" approach to mobilizing the body's resources. If a player is rushed back, the grade I tear can linger and cause pain for awhile. However, that wasn't the case with Lonzo as the team was very conservative. Full credit to Marco Nunez and Lakers medical staff for that for that.
RB: He was out for a little over 5 weeks and he was meticulously taken through incremental progressions until he could complete each without any pain.
SP: Right, but that being said, the ligament being pain-free doesn't mean that it's exactly the same as before. Ligaments, when stretched, can heal and re-tighten but may not be as tight as before. I think of it like those rubber bands that are placed around vegetables in the grocery store. If you over-stretch the rubber band, it will re-tighten and still be able to get the job done but they aren't as tight as before.
RB: So in other words, Lonzo may have had some increased knee laxity (looseness) even after he got back and the MCL was pain free.
SP: Exactly.
RB: Is that something you would consider a red flag?
SP: Absolutely not, but that looseness in the MCL could decrease the buffer against injury when the knee goes into an inward (valgus) position:
https://imgur.com/gnxTwEH
SP: The primary function of the MCL is to resist this valgus (inward) force. When the knee goes inwards, the inner (medial) aspects of the tibia (shin bone) and femur (thigh bone) gap/pull apart and the MCL is tensioned. Simultaneously, the outer (lateral) aspects of the tibia and femur come closer together:
https://imgur.com/kttd8sd
SP: If the MCL is looser than usual, the valgus (inward) force could result in the outer edges of those bones actually hitting together and creating a bone bruise.
RB: And you think that's what happened to Lonzo right?
SP: Based on how he got hurt, I do. For a direct external force (like getting hit by someone else's knee) to create a bone bruise, it takes a high amount of force. Like we saw with Iguodala in the Western Conference Finals when Harden's knee caught him hard.
Here's the video: https://i.imgur.com/fHKNZ6g.gif
And the moment of contact: https://imgur.com/uZ9jaNn
SP: On the other hand, in Lonzo's case, Dirk is just walking when there's contact between his leg on the outside of Lonzo's knee. There's no reason that would cause a direct impact bone bruise. Rather, it's much more likely that Lonzo's MCL was a little loose from the MCL grade 1 tear which made it less capable of resisting the inward (valgus) force from Dirk's contact - resulting in the lateral edges of Lonzo's tibia and femur hitting together, creating a "lateral knee contusion".
This, of course, is all speculation though.
RB: So to recap, Lonzo likely had some laxity in his MCL after coming back (which is normal after that injury) so when he got hit on the outside of the knee by Dirk, his knee went inward and the outer edges of the bones that make up the knee hit together.
SP: Right.
RB: If Lonzo was a patient, I know you'd go through a comprehensive manual diagnostic and bio-mechanical assessment to assess the knee laxity and other potential deficits. However, we aren't privy to that so based solely on these logical inferences, how would that inform your decision-making when it came to the Lonzo PRP procedure?
SP: Based off these inferences and having seen very similar series of events in other patients, it tells me that the main thing to be addressed in a Lonzo PRP procedure is, more likely than not, the looseness of that MCL. You precisely target the MCL with the PRP injection to re-tighten the ligament. This restores optimal mechanics and brings that injury risk buffer back to where it was prior to the injury.
RB: What about the bone bruise? Would you do anything specifically for that with PRP?
SP: Not directly. A bone bruise will heal with time and re-tightening the MCL will further help that process by taking pressure off the lateral compartment of the knee.
RB: In my head I'm imagining the knee joint as a ship that is slightly tilted to one side and then after the PRP procedure, it's now back in neutral.
SP: That's one way to put it.
RB: Anything else you would do or think was done during the Lonzo PRP procedure?
SP: Yeah, it would've made sense to also inject the knee joint itself, known as an intra-articular injection. This would directly address any inflammation that may exist in the knee joint, bringing the environment from a negative inflammatory one back to neutral. It would also indirectly address the lateral compartment bone bruise.
RB: Got it - so targeted precision injection into the MCL and then one into the knee joint itself. So how long would this procedure take?
SP: The procedure would take about 30 minutes, give or take.
RB: Once the Lonzo PRP procedure was done, what was his recovery process like?
SP: For the first 2-3 days, there's an increase in pain due to new inflammation process. After that, pain will wax and wane for the next 2-3 weeks as the inflammation process continues to play out. Around 3-4 weeks, the process is complete and the inflammation response is dialed down.
RB: What's his activity level looking like through this month or so?
SP: During the month after a PRP injection, patients go through rehab of the knee including physical therapy to incrementally strengthen and condition their body, while addressing any major mechanical deficits that could have contributed to increased stress on the knee.
RB: Like hip abductors (like the gluteus medius or minimus, to a lesser extent) that are weak, fatigued, or not activating?
https://imgur.com/eZKkReo
SP: Right. So that month off from full basketball activities for Lonzo was to allow the healing process to play out while continuing to work on his strength and conditioning.
RB: Alright, so now we're coming to the questions that everyone has been waiting for. What are the short and long-term implications of the Lonzo PRP procedure?
SP: In the short-term, the only real concern is the increase in pain from the inflammatory process but that's very short lived. If he's following rehab protocols, like he definitely seems to be, then there aren't any other issues.
RB: What about in the long-term, any implications for the Lonzo PRP procedure?
SP: The PRP procedure itself says nothing about his long-term injury concerns. In fact, I argue that as long as precise interventional orthopedic concepts were used to target the MCL, it likely reduces his injury risk going forward because it's tightening up the ligament to restore optimal mechanics.
RB: To add onto that, his MCL grade I tear was an impact injury rather than a non-contact mechanism. The latter would be far more concerning and indicate some underlying mechanical problem I'm pretty sure you agree but I'm gonna ask anyway because I yearn for approval, agree?
SP: 100%. An impact related mechanism of injury is often less concerning than a non-impact mechanism. Analyzing his movement mechanics would be far more useful in determining his injury risk whereas getting a PRP injection has no bearing on that.
RB: That's about all the questions I got for you man, much appreciated. One last request - if you could sum up PRP in one blurb and then how it applies to Lonzo.
SP: Image-guided PRP is a key component of interventional orthopedics that can precisely target and address tissue level problems using your body's own healing properties, with minimal drawbacks. In Lonzo's case, it's very likely being used to address the root cause of his bone bruise while reducing future injury risk via tightening up an MCL that was loosened from the grade I strain.
RB: Would you ever consider a BBB PRP co-branding?
SP: ...
Thanks for reading, until next time.
The original is on my sports injury blog, TheInjuryInsight

Note, I haven't fully read through or evaluated the quality these studies

Mind-muscle connection

Importance of mind-muscle connection during progressive resistance training [2015, N=18, trained men]

Abstract

Purpose
This study evaluates whether focusing on using specific muscles during bench press can selectively activate these muscles.
Methods
Altogether 18 resistance-trained men participated. Subjects were familiarized with the procedure and performed one-maximum repetition (1RM) test during the first session. In the second session, 3 different bench press conditions were performed with intensities of 20, 40, 50, 60 and 80 % of the pre-determined 1RM: regular bench press, and bench press focusing on selectively using the pectoralis major and triceps brachii, respectively. Surface electromyography (EMG) signals were recorded for the triceps brachii and pectoralis major muscles. Subsequently, peak EMG of the filtered signals were normalized to maximum maximorum EMG of each muscle.
Results
In both muscles, focusing on using the respective muscles increased muscle activity at relative loads between 20 and 60 %, but not at 80 % of 1RM. Overall, a threshold between 60 and 80 % rather than a linear decrease in selective activation with increasing intensity appeared to exist. The increased activity did not occur at the expense of decreased activity of the other muscle, e.g. when focusing on activating the triceps muscle the activity of the pectoralis muscle did not decrease. On the contrary, focusing on using the triceps muscle also increased pectoralis EMG at 50 and 60 % of 1RM.
Conclusion
Resistance-trained individuals can increase triceps brachii or pectarilis major muscle activity during the bench press when focusing on using the specific muscle at intensities up to 60 % of 1RM. A threshold between 60 and 80 % appeared to exist

Reply to the article by Halperin & Vigotsky (2016):

The results of Calatayud et al. (...) indicate that focusing on the pectoralis major and triceps brachii muscles during bench press exercise selectively enhanced their activation, and thus suggest a training strategy. However, the authors did not discuss the well-established negative effects that focusing on specific muscle groups has on exercise performance. For proper perspective of the results and their practical utility, it is helpful to note the interplay between negative and positive effects of different focus conditions.
[...]
Compared to external focus, adopting an internal focus decreases the force participants are able to apply in both single- and multi-joint exercises (Wulf 2013 ). Internal focus also reduces the number of repetitions subjects are able to com- plete in dynamic exercises, such as the bench press. It also shortens the time subjects are able to sustain an isometric contraction, such as a wall-sit (Wulf 2013 ).

Wulf (2013)

[...] in about 80 experiments significant advantages of external relative to internal foci (or, in some cases, distal relative to proximal foci) were found, sometimes in more than one measure of performance. Only a handful of those studies obtained null effects
[...]
Even though the attentional focus effect is now well established in the motor behavior literature, the translation of this research into practice is lagging behind. In interviews conducted by Porter, Wu, and Partridge (2010), 84.6% of track and field athletes who competed at national championships reported that their coaches gave instructions related to body and limb movements. As a consequence, the majority of athletes (69.2%) indicated that they focused internally when competing

Resistance Training Volume

Moderate Resistance Training Volume Produces More Favorable Strength Gains Than High or Low Volumes During a Short-Term Training Cycle (2015)

Resistance Training Frequency

Here's something I've always wondered about squatting every day: what's the advantage to squatting 6 times a week? At least your legs get one day of rest. And if squatting every day is the superior option, why don't we emulate this approach for the other muscle groups as well?

Increasing Lean Mass and Strength: A Comparison of High Frequency Strength Training to Lower Frequency Strength Training

Strength and conditioning research - Strength

For untrained individuals, greater training frequency leading to more volume could lead to greater strength gains. However, splitting the same weekly volume out over more sessions is unlikely to be beneficial. For trained individuals, splitting the same weekly volume out over more sessions might be beneficial, but evidence is very limited. Training with a higher frequency might be more effective for increasing strength because of improved inter-muscular co-ordination by virtue of a greater number of practice occasions.

Strength and conditioning research - Hypertrophy

For untrained individuals, altering volume-matched training frequency does not seem to have any effect on hypertrophy. For trained individuals, a higher volume-matched training frequency might to be superior to a lower volume-matched frequency for hypertrophy.

Effects of Resistance Training Frequency on Measures of Muscle Hypertrophy: A Systematic Review and Meta-Analysis (2016) - Schoenfeld, Krieger, Ogborn

When comparing studies that investigated training muscle groups between 1 to 3 days per week on a volume-equated basis, the current body of evidence indicates that frequencies of training twice a week promote superior hypertrophic outcomes to once a week. It can therefore be inferred that the major muscle groups should be trained at least twice a week to maximize muscle growth; whether training a muscle group three times per week is superior to a twice-per-week protocol remains to be determined.

Influence of Resistance Training Frequency on Muscular Adaptations in Well-Trained Men (2015)

Results showed significantly greater increases in forearm flexor muscle thickness for TOTAL compared to SPLIT. No significant differences were noted in maximal strength measures. The findings suggest a potentially superior hypertrophic benefit to higher weekly resistance training frequencies.

Deadlift injury risk

For those interested, I found some data on deadlifts and injury risk. Please don't look at this and assume that deadlifts are bad, but beware that deadlifts could injure your back if performed improperly. Some studies suggest that a more vertical back angle + bar close to body is beneficial and safer (i.e. sumo squat).

Understanding and Overcoming the Sticking Point in Resistance Exercise (2015)

certain lifting styles may inherently carry certain risks e.g. a wide grip on the bench press may increase the risk of shoulder injury and pectoralis major rupture [83], rounding of the back in the deadlift (which minimizes the moment arm of the load around the hip) the risk of spinal injuries [84], and buckling of the knees (valgus collapse– poorly synchronized or excessive tibial internal rotation and adduction relative to the knee flexion angle in a given stance) in the squat the risk of knee injuries [85].

Retrospective Injury Epidemiology of Strongman Athletes (2013)

N=213

Eighty two percent of strongman athletes reported injuries (1.6 ±1.5 training injuries/liftey, 0.4 ±0.7 competition injuries/liftey, 5.5 ±6.5 training injuries/1000 hr training).
From the strongman athletes’ injury data, traditional exercises accounted for just over half of injuries (deadlift 18%, squat 16%, overhead press 9%, bench press 6% and other 6%) (see Table 4). Strongman events accounted for 46% of injuries (9% stone work, 8% yoke walk, 6% tire flip, 5% farmer’s walk, 4% axle work, 4% log lift and press, 2% circus dumbbell and 8% other).

(...)

Traditional exercises, (deadlift and squat) produce exceedingly large hip extensor torques (1, 7, 11) and compressive or shear lumbar forces (7, 13). Winwood and colleagues (32) reported that 100% of strongman competitors performed traditional exercises (i.e. squat and deadlift) as part of their training programs; therefore the large percentage of lower back injuries with these exercises can be expected.

Which Patients With Low Back Pain Benefit From Deadlift Training? (2014)

Strength and conditioning professionals should not hesitate to use the deadlift exercise in their everyday practice, but before considering deadlift training for individuals with mechanical low back pain, our results suggest that pain intensity and the endurance of the hip and back extensors should be evaluated. For example, if low endurance of the hip and back extensors and high pain intensity are found in an individual with mechanical low back pain, then other interventions should be considered before initiating deadlift training. However, regardless of patients’ age, sex, body mass index, pain-related fear of movement, movement control,and activity, the deadlift exercise seems to be an effective intervention.

(...)

pain not only inhibits optimal muscle recruitment patterns but can also influence motor learning(13). More specifically, it has been suggested that pain may disturb motor learning due to its interference in the quality of performing a task that is being practiced (e.g., the deadlift exercise) (12). It might have therefore taken more time for participants with high pain intensity to learn how to perform the deadlift with the proper technique.

Exercise Highlight: The Sumo Deadlift (2016)

(...) deadlifts have also been shown to increase the strength and endurance of the trunk musculature (3,7) with no difference in activation between sumo and conventional stances (6). However, biomechanical analysis showed that the trunk posture is significantly more upright in the sumo deadlift leading to a decrease in the shear forces (8% reduction compared to conventional stance) placed upon the spine (2,5). Therefore, using the sumo deadlift may be a safer lifting technique in occupations where people are often required to lift bulky or heavy objects from the floor. Consequently, choosing the sumo deadlift as a part of higher-level lower back injury rehabilitation program could be highly beneficial.

Biomechanical analysis of the deadlift during the 1999 Special Olympics World Games (2001)

The increased forward trunk tilt at LO [LiftOff off the ground] in the current study resulted in a 10–20° decrease in hip angles compared with several other studies (1,5,11). The increased forward trunk tilt at LO may predispose the spine and back musculature to an increased risk of injury (2,3,6). Cholewicki et al. (3) reported that a more upright trunk at LO resulted in less anterior shear force at the lumbar L4/L5 joint. This was especially true in the conventional group, which had significantly greater forward trunk tilt than the sumo group at LO, since there is approximately 10% greater shear force and moment generated at the L4/L5 joint in the conventional deadlift compared with the sumo deadlift (3).
Keeping a weight close to the body during lifting is important in minimizing injury potential, especially to the lower back, because hip and spinal moment arms will decrease. This implies that the low-skilled group may have a higher risk of injury compared with the high-skilled group. Keeping the weight closer to the body also may enhance lifting performance.

(...)

The smaller hip moment arms and moments that result by keeping the barbell mass closer to the body also result in smaller L4/L5 joint moments and shear forces (3). This implies that the Special Olympics lifters may increase their risk of injury to the low back by keeping the barbell mass further away from the body. In addition, performance may also be compromised, since increasing hip and L4/L5 moments may also result in less weight being able to be lifted.

Injuries in strength training: review and practical application (2014)

Analysis of strength training is complex, since one or more training variables may interact with other training variables. However, the general nature of weight training injuries is quite similar among all those who train with weights, who are more likely to suffer from traumatic and chronic injuries because of various erroneous habits or poor technique (Hooper et al., 2014; Jones et al., 2000; Kerr et al., 2010; Weisenthal et al., 2014; Winwood et al., 2014). For these reason, neuromuscular training should be included in training programs, because it could reduce knee, shoulder, and low back injuries in adolescents and novice athletes in ST (Avery D Faigenbaum et al., 2014; Stevenson, Beattie, Schwartz, & Busconi, 2014)

(...)

Our review yielded three clinically relevant findings. First, most studies show variation in the definition of injury, methodologies, and analyses, which can lead to differences in results and conclusions obtained. Second, incidence and prevalence rate depend on definition and type of strength sports. Finally, lower back followed by shoulders and knees are most frequently injuries in ST.

Retrospective Injury Epidemiology of One Hundred One Competitive Oceania Power Lifters: The Effects of Age, Body Mass, Competitive Standard, and Gender (2006)

Similarly, the majority of the lower back injuries were associated with the performance of the squat and deadlift. This may be a consequence of the exceedingly large hip extensor torques (13, 23, 24) and compressive/shear lumbar forces (13, 15) reported for these exercises. A relatively greater proportion of injuries were reported to be acute (59.3%) than chronic in nature (40.7%). However, it is acknowledged that some injuries may appear acutely but actually reflect chronic degeneration (25). Unfortunately, the retrospective design and the lack of medical confirmation of each injury did not easily allow for determination of this third type of injury onset. The true rate of acute injuries may therefore actually be somewhat less than that reported

Medical History Associated with Adolescent Powerlifting (1983)

Mason7 and Troup5 expressed their theoretical concerns for possible deleterious effects of the dead lift on the spines of young lifters. Troup suggested a marked shearing stress, at the start of the dead lift, resisted by the pars interarticulanis of successive vertebrae in the region of the vertebral arch between the superior and inferior facets.
The low back region was the dominant injury site; 50% of all injuries occurred in this region. The knee, shoulder, and elbow were other sites of elevated injury occurrences. Musculoskeletal injuries (muscle pulls, tendonitis, cramps, sprains, broken bones, and dislocations) were perceived to account for 90.7% of all injury types.

Time Under Tension

• https://www.researchgate.net/publication/299468884_Kinematics_and_Kinetics_of_High_and_Low_Velocity_Resistance_Training_Equated_by_Time_Under_Tension_Implications_for_Hypertrophy_Training
  
• https://www.researchgate.net/publication/279153672_Variations_in_Repetition_Duration_and_Repetition_Numbers_Influence_Muscular_Activation_and_Blood_Lactate_Response_in_Protocols_Equalized_by_Time_Under_Tension
  
• https://www.researchgate.net/publication/282534834_Dose-Response_Relationships_of_Resistance_Training_in_Healthy_Old_Adults_A_Systematic_Review_and_Meta-Analysis
  
• https://www.researchgate.net/publication/287204240_Intramuscular_Anabolic_Signaling_and_Endocrine_Response_Following_Resistance_Exercise_Implications_for_Muscle_Hypertrophy
  

Resistance exercise protocols that maximize muscle fiber recruitment, time-under-tension, and metabolic stress appear to contribute to intra-muscular anabolic signaling; however, there does not appear to be a minimal threshold or optimal training scheme per se for maximizing muscle hypertrophy

• https://www.researchgate.net/publication/6820634_The_effects_of_varying_time_under_tension_and_volume_load_on_acute_neuromuscular_responses
  
• https://www.researchgate.net/publication/228830087_Evidence-Based_Resistance_Training_Recommendations
  

Exercises should be performed at a repetition duration that maintains muscular tension throughout the entire range of motion. Olympic lifting, plyometric and ballistic exercises remove tension from the muscle and apply greater forces through joints and associated tissues causing a greater potential for injury.

Overtraining

It looks like we need to distinguish between overreaching and overtraining. Here are some interesting quotes from research articles on the topic:

Overtraining Syndrome (2012)

OTS appears to be a maladapted response to excessive exercise without adequate rest, resulting in perturbations of multiple body systems (neurologic, endocrinologic, immunologic) coupled with mood changes. Many hypotheses of OTS pathogenesis are reviewed, and a clinical approach to athletes with possible OTS (including history, testing, and prevention) is presented.
OTS remains a clinical diagnosis with arbitrary definitions per the European College of Sports Science’s position statement. History and, in most situations, limited serologies are helpful. However, much remains to be learned given that most past research has been on athletes with overreaching rather than OTS.

Does overtaining exist? An analysis of overreaching and overtraining research (2004)

The majority of knowledge on markers of overtraining is based on the results of studies that have deliberately induced a state of overreaching in athletes. At present there is insufficient evidence to draw accurate conclusions on the similarities or differences between the two states

Prevention, diagnosis and treatment of the overtraining syndrome: Joint consensus statement of the European College of Sport Science (ECSS) and the American College of Sports Medicine (ACSM) (2013)

A difficulty with recognising and conducting re-search into athletes with OTS is defining the point at which OTS develops. Many studies claim to have induced OTS but it is more likely that they have induced a state of OR in their subjects. Consequently, the majority of studies aimed at identifying markers of ensuing OTS are actually reporting markers of excessive exercise stress resulting in the acute condition of OR and not the chronic condition of OTS. The mechanism of the OTS could be difficult to examine in detail maybe because the stress caused by excessive training load, in combination with other stressors might trigger different ‘defence mechanisms’ such as the immunological, neuroendocrine and other physiological systems that all interact and probably therefore cannot be pinpointed as the ‘sole’ cause of the OTS.
A primary indicator of OR or OTS is a decrease in sport specific performance, and it is very important to emphasise the need to distinguish the OTS from OR and other potential causes of temporary under-performance such as anaemia, acute infection, muscle damage and insufficient carbohydrate intake

The Overtraining Syndrome: A Meta-Analytic Review (2013)

the data presented in this meta-analysis indicate considerable immune-suppression and increased stress in athletes who experience the OT syndrome (1,5,6,7,10,12,16,21,22,25,26,27). From this analysis, a negative effect size for the cardiovascular markers of HR and SBP indicates questionable alterations from N to OT in subjects (18,23,24). Increased sympathetic and/or decreased sympathetic influence may be affected in the OT condition. However, low effect size calculations allow for non-determinant conclusions related to cardiovascular indicators of the OT syndrome (3,13,15). Lastly, athletes in the OT state are likely to experience disturbances in sleep, self-perception, and mood factors (11).

Overtraining, Exercise, and Adrenal Insufficiency (2013)

Overtraining Syndrome (OS) has been described as chronic fatigue, burnout and staleness, where an imbalance between training/competition, versus recovery occurs. Training alone is seldom the primary cause. In most cases, the total amount of stress on the athlete exceeds their capacity to cope. A triggering stressful event, along with the chronic overtraining, pushes the athlete to start developing symptoms of overtraining syndrome, which is far worse than classic overtraining. Overtraining can be a part of healthy training, if only done for a short period of time. Chronic overtraining is what leads to serious health problems, including adrenal insufficiency.
Severe overtraining over an extended period can result in adrenal depletion [46-48]. An Addison- Type overtraining syndrome, where the adrenal glands are no longer able tomaintain proper hormone levels and athletic performance is severely compromised has been described by researchers [11,13,49-51].
CFS (Chronic Fatigue Syndrome) could be caused by or mistaken for AI (Adrenal Insufficiency). There is commonly a decrease in exercise capacity in CFS, which may be result of AI. Overtraining may contribute to or even cause AI. Cortisol levels are lowered and ACTH is increased during overtraining, while a reduced responsiveness to ACTH, and a reduced responsiveness to CRH are found. If the physical stress of overtraining is not removed, adrenal issues may continue or become more severe. Severely over trained athletes may develop Addison’s Disease

Monitoring the athlete training response: subjective self-reported measures trump commonly used objective measures: a systematic review (2015)

Subjective measures reflected acute and chronic training loads with superior sensitivity and consistency than objective measures. Subjective well-being was typically impaired with an acute increase in training load, and also with chronic training, while an acute decrease in training load improved subjective well-being.

Sleep

Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society (2015)

• Sleeping less than 7 hours per night on a regular basis is associated with adverse health outcomes, including weight gain and obesity, diabetes, hypertension, heart disease and stroke, depression, and increased risk of death. Sleeping less than 7 hours per night is also asso- ciated with impaired immune function, increased pain, impaired performance, increased errors, and greater risk of accidents.
• Sleeping more than 9 hours per night on a regular basis may be appropriate for young adults, individu- als recovering from sleep debt, and individuals with illnesses. For others, it is uncertain whether sleeping more than 9 hours per night is associated with health risk.

The impact of training schedules on the sleep and fatigue of elite athletes (2014)

At present, we know very little about the sleep needs of elite athletes, particularly in terms of the amount required to reach and/or maintain optimal levels of performance. The results of the current study indicate that elite athletes obtain an average of 6 h and 30 min of sleep per night. Given that 6 h of sleep per night in untrained individuals is associated with neurobehavioural deficits in daytime performance, it is reasonable to suggest that this level of sleep loss would also impair sports performance and recovery. One factor that affects the amount of sleep an athlete obtains is the timing of their training. When designing schedules, coaches should be aware of the implications of the timing of training sessions for sleep and fatigue. In particular,schedules that require athletes to train early in the morning reduce sleep duration and increase pre-training fatigue levels.

Sleep/wake behaviours of elite athletes from individual and team sports (2015)

The main finding of this study was that on average athletes obtained 6.8 h of sleep per night. This amount of sleep was considerably lower than the 8 h of sleep per night necessary to prevent the neurobehavioural deficits associated with sleep loss (Belenky et al.,2003; VanDongen et al.,2003).
While it is recognised that healthy, fit individuals tend to sleep longer and have higher quality of sleep compared to their sedentary counter-parts, there are data indicating that when athletes’ training demands are excessive the amount and quality of sleep may become disrupted (Shapiro,Bortz, Mitchell, Bartel, & Jooste,1981).

Sleep and Athletic Performance: The Effects of Sleep Loss on Exercise Performance, and Physiological and Cognitive Responses to Exercise (2014)

Although sleep is generally considered critical for human and athletic performance, there are mixed results regarding objective performance decrements in the current scientific literature. Individual athletes appear to lose sleep just prior to competing or if forced to train at early times; however,evidence for such instances in team sports is lacking.Exercise performance seems to be negatively affected during periods of SD (specifically endurance and repeated exercise bouts), although conflicting results exist for the effect of acute SR, as performance during maximal one-off efforts (in particular for maximal strength) is generally maintained. Possible reasons for these differences could be due to contrasting research designs and statistical power.The effects of sleep loss on physiological responses to exercise could potentially hinder muscular recovery and lead to a reduction in immune defense, although this still remains speculative. The majority of studies focusing on sleep loss and cognitive performance and mood responses have found detriments to most aspects of cognitive func-tion (i.e. RT) and mood stability, results that potentially could hinder the neurocognitive components of many sports. Despite common assumptions around the importance of sleep, the lack of scientific evidence (especially in elite athletes) suggests future research into the examination of sleep and athletic performance is warranted.

Sleep As A Strategy For Optimizing Performance (2016)

This study is from Journal of special operations medicine, and I couldn't get access to the full article. Even so here are some quotes from the abstract:

Insufficient sleep negatively impacts safety and readiness through reduced cognitive function, more accidents, and increased military friendly-fire incidents. Sufficient sleep is linked to better cognitive performance outcomes, increased vigor, and better physical and athletic performance as well as improved emotional and social functioning. Because Special Operations missions do not always allow for optimal rest or sleep, the impact of reduced rest and sleep on readiness and mission success should be minimized through appropriate preparation and planning. Preparation includes periods of "banking" or extending sleep opportunities before periods of loss, monitoring sleep by using tools like actigraphy to measure sleep and activity, assessing mental effectiveness, exploiting strategic sleep opportunities, and consuming caffeine at recommended doses to reduce fatigue during periods of loss. Together, these efforts may decrease the impact of sleep loss on mission and performance

The Impact of Sleep on Youth Athletic Performance (2015)

Sleep is critical to the body’s repair process for an athlete subjected to daily physical stress. Some of the negative effects of sleep deprivation include a decrease in reaction times (Scott, McNaughton, & Polman, 2006), and decreased strength (Riley & Piercy, 1994). During sleep, growth hormone is released and leads to muscle development. The impairments to the immune and endocrine systems (Reilly & Edwards, 2007)that result from sleep deprivation may impair the recovery process and adaptation to training (Halson, 2008).Sleep plays an important role in the repair process following an injury, and lack of sleep impairs injury recovery (Schwarz, Graham, Li, Locke, & Peever, 2013).Sleep deprivation can also cause a higher body mass index, leading to a greater risk of becoming obese (Ferrie, Shipley, Cappuccio, Brunner, Miller, Kumari, & Marmot, 2007). Due to these factors, coaches may be dealing with athletes who are moody, slower, weaker, slower to recover, overweight, and more susceptible to illness and injury.

Sleep Improves Memory: The Effect of Sleep on Long Term Memory in Early Adolescence (2012)

Sleep plays an important role in the consolidation of memory. This has been most clearly shown in adults for procedural memory (i.e. skills and procedures) and declarative memory (e.g. recall of facts).
Declarative memory is significantly improved by sleep in a sample of normal adolescents

Sleep, circadian rhythms, and athletic performance (2014)

Sleep deprivation was found not to influence performance in a number of studies [6,8e11,13,23], most of which measured short-term performance with a considerable anaerobic component. However, a large number of the studies observed a decrease in performance after sleep deprivation or recovery from sleep deprivation[14e22],many of which measured endurance performance. It is likely that psychological effects (e.g., motivation) contribute to the adverse effect of sleep deprivation upon endurance performance[20]. This proposed mechanism is in line with theoretical notions concerning motivation as a mediator of the effects of sleep deprivation[120].Sleep deprivation seems to influence evening performance to a greater extent than morning performance[7,20,25]. The reduced evening performance is likely a result of lower circadian rhythm amplitude after sleep deprivation[7,121]. Only a minority of the studies on total sleep deprivation measured performance in the evening [7,20], a limitation which may have led to fewer significant results.

Sleep, Recovery, and Athletic Performance:A Brief Review and Recommendations (2013)

Although sleep is recognized as an essential component of recovery from athletic training and anecdotally reported to be the single most efficacious recovery strategy (8), assessment of sleep quality in competitive athletes reveals a substantial prevalence of poor sleep quality (19)
These data indicate that athletes may have an increased need for sleep with general recommendations suggesting 7–9 hours to ensure adequate physio-logical and psychological recovery following training, of which 80–90 % should be during the night (3). Further-more, adequate sleep is particularly important for athletes who are injured,traveling, or in heavy periods of training or competition phases (23). Of particular concern when training elite athletes is the identification of signs and symptoms of poor sleep quality,indicative of sleep deprivation, which may result in an inability to appropriately recover from training.

The author goes on to make five practical recommendations for athletes trying to optimise sleep. Read the full article for details

Stress, Sleep and Recovery in Elite Soccer: A Critical Review of the Literature (2015)

Sleep deprivation may be detrimental to the recovery processes after a match, that is, impaired muscle glycogen repletion, impaired muscle damage repair, altered cognitive function and an increase in mental fatigue. Consequently, prolonged sleep deprivation may act as an additional stress to the stress imposed by exercise itself, similar to that of altitude or heat [132] or training in conditions of reduced carbohydrate availability [133]

Vitamin D

• Low vitamin D status in Europe: moving from evidence to sound public health policies (2016)
  
• Vitamin D: An overview of vitamin D status and intake in Europe (2014)
  
• Vitamin D deficiency in Europe: pandemic? (2016)
  

Mortality

• Mortality associated with body fat, fat-free mass and body mass index among 60-year-old Swedish men¾a 22-year follow-up. The study of men born in 1913

MMA & injury risk

• Risk of cervical injuries in mixed martial arts
  
• Risks of traumatic neuromechanical injury associated with boxing and mixed martial arts
  
• Incidence of Injury in Professional Mixed Martial Arts Competitions
  

Strength and injury risk

• Which strength sport is most likely to cause an injury?

Anti-inflammatory drugs and supplements

• The Use of Nonsteroidal Anti-Inflammatory Drugs for Exercise-Induced Muscle Damage
  
• Fish oil supplementation suppresses resistance exercise and feeding‐induced increases in anabolic signaling without affecting myofibrillar protein synthesis in young men
  
• Effect of ibuprofen and acetaminophen on postexercise muscle protein synthesis
  
• Ibuprofen Ingestion Does Not Affect Markers of Post-exercise Muscle Inflammation
  
• Effect of ibuprofen and exercise training on bone, body composition, and strength in older women