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On Understanding the Difference Between Positional vs. Compensatory Influence on Muscle…

To understand the positional and compensatory influence of the Left AIC, you need to look at the AIC as several muscles working together as one functional unit, and that this functional unit has rotational influence on the pelvis toward the right.  After this unit directs the pelvic girdle toward the right, it is compensatory activity at the left hip that actually ERs the hip enough for the knee and foot to be positioned straight forward for walking.  In other words, the Left AIC directs the pelvis toward the right, but it does not fully turn the femur into the needed amount of ER to walk forward, including ER from midstance to pushoff.  The deep ERs of the hip have to assist with this.  That is the compensatory part. 

The right hip has to IR to walk, but the pelvis that is already directed toward the right because of the influence of the Left AIC already has the right hip in the IR needed for walking without requiring any compensatory activity.  So all of these muscles on these 3 pages are in a bad position for performance before they are even asked to move the pelvis or femurs because of what the Left AIC did to the bones that position each of them.  This document linked above outlines the faulty position of all of these muscles to help the clinician understand the why so many of these muscles work more actively than they should or fail to become active enough during human movement patterns.  All 3 planes of motion are taken into consideration, because without an understanding of all 3 planes, a full understanding of muscle position and muscle function will be lost.