Relativity: The Squat
The ability for one object to move with respect to another seems to underpin nearly all, if not all aspects of nature that we have observed. How people move is no different. Relativity within movement means that we are able to move one tissue relative to another. This could be two bones, muscles or any other soft tissue. Without relativity, movement does not exist.
Squatting is a complex movement pattern that involves coordination from many different perspectives. For the purposes of this short blog post, we are going to stick to three phases with the understanding that each phase blends into the others on a continuum.
The initial phase, before any descent, corresponds most closely with a forward center of gravity, a position that by traditional standards looks like terminal stance in walking. This position involves a greater degree of external rotation or an outward turn of the joints with respect to midline. Everything that connects to joints is biased toward this lateral turn. Active musculature that you might consider could be glutes, lats and traps. Their activity influences the stiffness of connective tissues and limits the inward turn necessary for the descent of the squat.
As the drop into the squat is initiated, the musculature responsible for an outward turn begins to loosen its grip on position. Their activity diminishes in order for the center of gravity to begin to move downward and inward. If we looked at joint positions, they are beginning to compress and relativity between bones is beginning to diminish. The guts of the abdominal cavity are slowly moving down into the pelvis, and particularly the posterior pelvic outlet for the squat to continue to progress toward the floor. The water content within a person is starting to push back on tissues and right at the point of parallel, surface area is at a maximum. This is where the center of gravity has shifted the most from the top position.
The last phase of the descent involves a reactivation of musculature that had diminished in its activity level. The pelvis begins to close off once again and connective tissues now become the primary movers. They absorb the energy from height of the squat and they provide a tremendous amount of kinetic energy on the return to standing. Center of gravity begins to move forward again and the descent is complete.
The return from the bottom of the hole reverse engineers this pattern and once again center of gravity shifts from forward, to backward and finishes in the forward position. All predicated upon relativity between tissues to shift pressures and alternate energy types.
Austin Ulrich, Physical Therapist
