by: Kevin Cann
Knees caving in on the squats, aka valgus collapse is one of the most common faults we see when coaching the squat.
A number of factors can be the culprit such as:
poor ankle mobility
poor motor control
These are all valid reasons why we might be seeing the knees cave inward in the squat. However, there is another common issue that is not often thought about, and that is with the lats.
Yes, I just said that your back muscles can influence your knee position during a squat.
Believe it or not, the glutes actually work best when there is a co-contraction of the lats. This is more than likely due to their shared insertion point into the thorocolumbar fascia. Your transverse abdominus also inserts into the thorocolumbar fascia.
The transverse abdominus has one role and that is to compress our abdominal contents. Basically, this is our body’s own lifting belt. Due to the lats sharing an insertion point with this spinal stabilizer, it would be safe to say that the lats are an important stabilizer of the spine.
Dr. McGill and colleagues looked at trunk muscle activation and lumbar spine movement during strongman events like the farmer’s walk, super yoke, Atlas stone lift, suitcase carry, keg walk, tire flip, and log lift. What he found was that the lats were the most activated muscle in all of the lifts (1). There are no pulling or rowing motions in any of these events which suggests to me that the lats play a major role in stabilizing the spine under heavy tension.
So, why would stabilizing the spine be important to stopping my knees from collapsing inward on the squats? Well the hips and the shoulders are both attached to the same spine. We need to engage the lats during the squat to stop the weight from forcing our spine into flexion. If our spine flexes we cannot properly align the femur in the hip joint to create the necessary tension to “drive our knees out.”
Many people just do not know how to properly activate their lats. Typically, when I ask a client where they feel a lat activation exercise, they point to the part of the muscle that is under their armpit and along their ribs. This is not a strong contraction of the lats because the lats insert all of the way down by the tailbone.
Others will start the squat with the lats tight, but lose it on the way down. Perhaps this is due to the eccentric contraction of the glutes? As our glutes are stretching it just may be harder to maintain the tightness necessary in the lats. Remember in order for the glutes and lats to work at their full potential they need a co-contraction. This is just a guess and who knows, I may be way off base here.
Anyways, when we lose the lats (or don’t even have them from the start) it is much harder to use our glutes. Also, at the bottom position of the squat our glute medius is in its toughest position to exert force. The body will always take the path of least resistance and put itself in a mechanical advantage.
Internal rotation at the hip (this is really what is causing the knees to cave inward) gives our glute medius a greater mechanical advantage. At the same time though this decreases the mechanical advantage of the glutes. However, our body might not care about this so much since it knows we can’t maximally contract the glutes due to lack of contraction in the lats. At the same time the hip internal rotation puts our hip adductors in a good spot to extend the hips. The hip adductors are our 3rd strongest hip extensors (with weak glutes these move up the chain. This is why athletes suffer groin pulls in sports).
Basically, due to the lats not being contracted, the glutes are not capable of doing their jobs to their full potential. The body, to take the path of least resistance, shifts into hip internal rotation to give our glute medius better leverage as well as our hip adductors better leverage to extend the hips.
This is the human body getting it done.
When squatting or performing any movement for that matter take a step back and look at the whole thing. The human body is a system, not a collection of pieces. Each part of the system affects the others. Sometimes just trying to drive your knees out will not work. Sometimes it is because your ankle mobility is poor, quads are tight, glutes are weak, have poor motor control, and sometimes it is actually because your lats are stiff.