Surface Area

Space is at a premium when it comes to movement. We all only have so much of it, and how we decide to warp it dictates our movement options. Joints have surfaces, meaning bones interact with one another in varying ways. The extent to which their surfaces interact has large implications for our degree of comfort while we move.

Surface contact influences force absorption and production significantly. Consider for a moment performing a squat on your toes versus with flat feet. The version on your toes will place high pressures on those toes and that small point of contact will also limit how much weight you can lift. Reimagine the squat, but standing with your feet flat on the ground. The pressure distribution is much greater across the entirety of your feet and that will provide you with a much greater ability to both absorb and produce force, i.e. lift heavier weights.

Carry this idea over the joint mobility. If we train ourselves to move within only certain parameters, joints stay within those boundaries and tissues get loaded the same way repeatedly. Applying external loads reinforces those boundaries and the space available diminishes. This strategy is incredibly useful for producing force, however the tradeoff is that it limits movement options. The surface area between the bones gets smaller and smaller, focalizing pressures eventually reaching a threshold where pain develops as your body attempts to protect itself from injury.

This is not a strange phenomenon as most people undergo these changes as their life progresses. Movement variability and altering how you move with intention can reduce the rate at which these changes occur. Exercises and manual interventions whether by a professional or self-assisted can be useful in reducing focal loading and promoting greater movement options.

Austin Ulrich, Physical Therapist