The Knees-In vs. Knees-Out Squat Debate – It’s not about the knees.

Recently I was introduced to Conrad Stalheim’s article, “Moderating the Knees In Versus Knees Out Squat Debate” summarizing an ongoing debate about knee position during the squat. This article does a great job introducing the topic and led me to the right links so that I could educate myself without getting lost (too much) in the personal tirades that are so often a part of an impassioned debate.

Because I’m an uber-geek, I had to weigh in on this awesome discussion. Though I think any professional discussion about human movement is an awesome one, this one gets me particularly geeked out. I want to start by saying that I am not a Crossfitter or an Olympic Lifter or a Power Lifter. I am not actually an ‘-er’ of any type . I love exercise and lifting heavy things. I love the intricacies of human movement and I specialize in applying those loves to athletes and active people who have chronic injuries preventing them from exercise or sport. I am highly rewarded by seeing my clients achieve movement or return to sport without pain.

I watched Kelly Starrett’s video series with Diane Fu and Roop Siota to establish an understanding of their coaching technique. I also read through Bob Takano’s blog series (referenced in Quin Henock’s article) to fully understand his input and that of the other professionals he involves in the discussion. Of course, I also read Bob Green’s article which seems to have been thrown in the mix though it wasn’t part of the initial discussion.

The squat is not about the knees
Though some of the back and forth between Takano and Fu reads differently, in his video series, Kelly Starrett continually states that ‘knees out’ is a cue, not a position. ‘Knees out’ is a cue that we all use or have used when someone is initiating their squat with a valgus knee position. Here’s the thing. It is a terrible cue. The knees are buckling in for a variety of reasons, lack of muscle control, soft tissue restriction, all of the above. Telling someone to push out their knees mid-squat doesn’t correct the problem. It simply puts them into a new bad position. The better cue here would be, “stop.”

Let’s take for instance the woman who has scar tissue thanks to multiple C-sections or the man who has scar tissue post hernia repair. Asking for these athletes to push their knees out will simply pull against that adhesion and cause for an abnormal response elsewhere in the chain. It is like tugging on a skirt that is too short in hopes of covering your butt. You are likely to cover the rounded bottom, only to expose the crack. By pushing knees out, you haven’t lengthened the tissue.

Can you lengthen tissue to improve your squat simply by doing squats? You bet. This is an excellent method of improving your functional range of motion while improving strength and stability.

Two rules for using squats to improve mobility and strength

  1. If there is a history of injury, you must first identify and address any associated adhesions and altered neuromuscular firing patterns.
  2. You must stay within the available range of motion while executing the movement. You will find that through repetition and intermittent static holds at the bottom of the squat, you will continually improve your range of motion.

Position Creates Power
Any motion is about creating maximal Ground Reaction Force to elicit the equal and opposite reaction of movement. As Quin Henock says in his article, “ Where I come from, the goal of a squat is to stand up, so maximally loading the muscles that help you do that is probably a good idea.” Pushing your knees out during the decent phase of a squat may make the squat look like it is supposed to look, but it will also put your femur into an externally rotated position. By putting the femur into an externally rotated position, not only do you limit your flexion range of motion, as Henock points out, but you also lose your ability to load the muscles most needed to get back up. To create ground reaction force, you must push down into the ground. This involves quads, hams, gluts, adductor magnus, and a host of other muscles. For these to provide power at the bottom of the squat, they must be pre-stretched or loaded. If you are actively pushing out throughout the decent, you are not allowing these muscles to load; you are holding them in tension thereby eliminating any stretch reflex action potential at the bottom of the squat.

Instead, throughout the decent, relative internal rotation at the hip must occur which allows for the transverse fibers of the gluts and adductor magnus to stretch in the same manner that the sagittal fibers stretch during hip flexion. This is not knee valgus. When executed properly, the knee will track over the foot. From here, you have efficiently loaded your hip complex (like stretching a rubber band) and it is prepped for explosion.

Cueing Recommendations
Enough with the biomechanics you say? OK, I’ll move on (though it kills me, I love that stuff).
If knee valgus is simply a product of the awkward movements of a beginner, I cue two things –‘Initiate movement from the hips’ and ‘push into the floor’.

Why ‘push into the floor’? Your butt and your feet talk to each other. It is the tensional changes of the fascia in the foot that communicate to the hip complex proprioceptively. This communication calls for eccentric muscle firing providing a stable and mobile environment where the muscles of the hip complex can work synergistically to allow coordinated movement. Next time you have a relatively athletic person doing squats and there is some knee buckling, try the ‘push into the floor’ or ‘push through the floor’ cue and see what happens.

Knee movement is possible and important in knee flexion. This concept of ‘locking’ the knees while in flexion to create stability and to protect from injury will cause injury.
First, locking a joint makes it immobile. It may be stable, but that does not make it an efficient athletic position from which to move. Second, the knee joint locks through the Screw Home mechanism in extension, not flexion. The reason for this is clear. In knee extension, the femur rests on the tibia allowing for muscular rest while standing. In knee flexion, whether walking, running, jumping, or squatting there is a necessary internal rotation that occurs at both the femur and tibia in order to wind up or preload the soft tissue. My favorite demonstration of this range of motion is watching a Running Back who needs to change direction. The athlete twists his foot into position to apply opposing force upon the ground. With this ground reaction force, the joints of the foot, ankle, knee and hip often create angles our textbooks call impossible and dangerous. More often than not, the result is not a torn ACL, but simply the amazing movement and skill of a talented player. Here are some great stills: one of Mike Hart on and one of Ray Rice on Both of these guys had to place a massive amount of power through an apparent valgus knee and to my knowledge, they are both still on the active list. Mike Hart on

Ray Rice, Image from

In researching knee mechanics in order to better design an efficient prosthetic leg, Kamran Shamaei & Aaron M. Dollar*, find the normal rotation of the joint ranging from 2-23 degrees. That is a lot of rotation at a joint we call a ‘hinge’. Michol Dalcourt offers great visuals in his video describing this motion.

On to Dan Green’s initial point about knees in.
Dan Green’s initial comments about using a knees-in technique when driving out of the hole (not when initiating the squat) are momentary in the initial article, but caused so much discussion and misinterpretation that he needs to explain himself further here.

What I see in his video and that of Long Qingquan (and many others I’ve found) is a highly trained athlete using a highly skilled technique to generate improved performance. It is clear to me that the move improves Qingquan’s performance. (Man, I love watching this stuff!) It is also clear to me that his performance is far and above the caliber of most people in the world and the movement he is performing is highly specialized.

Training Olympic Lifters or Power Lifters to be better at their sport is not my job. It is my job to get them back to sport when they are injured. In my job, I will often examine form or movement during the sport to see if there are techniques that are contributing to the injury. What I see here wouldn’t raise major red flags for me. Why? What I note is that the feet are flat without any apparent inversion or eversion at the calcaneus. In a still photo, the knee comes into a position that I might describe as valgus, but in movement I wouldn’t describe it as such. It closer simulates adduction, where the normal range of motion is being taken advantage of to allow for additional pre-stress of the hip complex, thereby allowing for maximization of ground reaction force. Each of us is different and to anyone teaching or employing this technique, I would advise a close listen to the feel of the move and, as always, executing the move within effortless range of motion. In watching Green and Qingquan, the amount of movement each utilizes is very different. Not a novice move, this is something taught after skill and coordination have been mastered. Everyone I’ve watched execute this move are in proper hip flexion, foot position, and have more than 90 degrees of knee flexion. If I saw someone using it as a cheat, that would be a huge red flag for me.

What about Tensegrity?
If you aren’t familiar with the term tensegrity, you must learn more. Without belaboring this point too much, I’ll simply mention that I haven’t seen any discussion regarding the effect of the fascia on the movement pattern. I quote Robert Schleip, “Recent ultrasound based measurements indicate that fascial tissues are commonly used for a dynamic energy storage [catapult action] during oscillatory movements such as walking, hopping or running. During such movements the supporting skeletal muscles contract more isometrically while the loaded fascial elements lengthen and shorten like elastic springs (Fukunaga et al. 2002).” Knowing this, the quickness of an Olympic lift is perhaps apt to rely heavily during certain points in the lift upon the catapulting action of the fascia. I would love to see a study along those lines. (Like I said, I’m a complete geek about this stuff.) If true, I would think that this creates a deeper chasm in the difference between the power lift and the Olympic lift. Food for thought.

My perspective on the squat
Here is my simplified perspective on squat form and cueing the squat. Whether teaching someone else or perfecting your own:
1. Create a solid foundation of hip and foot mobility and stability by eliminating any soft tissue adhesion or neuromuscular mis-firing left over from any injuries. (See someone skilled in this area of exercise.)
2. In the absence of injury, set that same foundation by slowly and methodically improving your squat range of motion by executing moderate load squats within the range you do have. Employ intermittent static holds at the bottom of the squat to ‘push you down’.
3. Use the cues – ‘spine long’, ‘move from the hips’, & ‘push into the floor’. Allow the knees to track naturally over the feet, they are following instructions from your hips.
4. If those cues are not enough to keep the knees tracking naturally over the feet, go back to steps 1 and 2. You are lacking mobility, strength, motor coordination or all of the above. You may need help from someone who specializes in corrective exercise.

As someone who first experienced knee pain at the age of 16 thanks to chondromalacia and now can execute a deep overhead squat without pain, I am a firm believer in the squat. I love the saying, “Shut up and Squat.” Just make sure you have the mobility and motor control to do it right.

(Aside. Those of you with Mel Siff’s 6th edition of Supertraining – 2003, check out the pictures of Mel in the front. At the bottom of his snatch, he appears to be “knees-in”. These pictures were taken in the 70’s. I met him in 2003 and he was still doing ass-to- heels snatches without knee pain. More food for thought. )

*Shamaei, Kamran & Dollar, Aaron M.; “On the Mechanics of the Knee during the Stance Phase of the Gait” 2011 IEEE International Conference on Rehabilitation Robotics, Rehab Week