More mobility, more problems?

Do we over prescribe mobility?

The body does not function optimally on extremes, and yet many times there is the assumption that chasing more mobility in the squat leads to better performance. In respect to the Joint by Joint theory (Mike Boyle, Gray Cook),“optimal movement occurs with an alternating series of stable segments moving on mobile joints”. We know that when you lack mobility in a mobile joint, a stable joint becomes more mobile to compensate.

The Joint by Joint Theory and the Back Squat

Propose there were disturbances in this continuum during the squat; the hip flexors are locked short, the hamstrings locked long, and the ankles stiff. As the range of motion (ROM) increases to the limited depth, the pelvis will posteriorly tilt (butt wink) and the lumbar spine loses its stability. Coupled with the lack of dorsiflexion this can cause the trunk to lean forward and the knees may valgus. But! The same can occur when there is excessive mobility but a lack of stability.

The Joint by Joint theory highlights the tendencies joints have, either the need for stability or mobility depending on the function of these joints. Although in saying this there are exceptions. For instance, tight hip flexors get a lot of blame for poor squat performance, but they play a vital role in the stability of squat. When performing a squat, the hip flexors contract to stabilise and control the pelvis during the squat. It's important to remember that stability is the ability to remain stable in the presence of constant change, throughout the entirety of a movement. As we increase hip mobility
we inherently decrease stability, not only at the hips but the pelvis, lumbar spine and knees. While we can improve mobility in a short time frame, it takes longer to establish stability.

For example; after increasing the amount of mobility at the ankles and hips, an individual will not necessarily have the relative stability to control the amount of increased mobility required during the full ROM in the squat. They would not be able to efficiently control the eccentric phase of the squat and would attempt to dive bomb, to bounce out of the bottom in the hopes to overcome a heavy load. Basically, slamming into joint end range and turning your connective tissue structures into an abused suspension system. As Charles Poliquin, said,” you cannot fire a cannon from a canoe “. For that reason, you cannot expect to be strong and exert force from an unstable position.

What follows is the domino effect of joints struggling to stabilise and coordinate the movement during the concentric phase. Instability at the hips during the eccentric phase of the squat, specifically towards end ROM, increases movement in the pelvis and lumbar spine resulting in an increased posterior tilt (butt wink). Unstable hips can also cause excessive internal rotation and adduction of the femur. Down the kinetic chain this creates instability at the knee causing possible valgus with potential for loss of midfoot stability or our tripod foot due to overpronation. Without control of the lumbopelvic region the core becomes unstable, causing the trunk to lean forward. We now have a squat that resembles more of a good morning to save the lift.

There is constant stimuli that drives movement - we rely on joint proprioception to influence the neuromuscular system, to provide feedback for how much muscle activation and tension is required to stabilise and coordinate movement through a given ROM. Mobility must be relative to the demands and ability of the system stabilising it and your capability for quality movement is constrained by its capacity to control it. Without control, we reinforce poor associations to movement and to our nervous system about how our joints interact in Space.

Work for your mobility. Earn your stability. Own your position in the squat.