Adductor Function

Question:

I understand that the adductor complex has responsibility in all three planes of motion. My question is: Of the five muscles that make up the adductor complex, which muscles are responsible for internal rotation, which ones for external rotation and at which points in the gait phase specifically, or do they all primarily work together in the same direction at the same time when producing concentric and eccentric force? Are any of these individual muscles specifically susceptible to lengthening and/or shortening more than others within the complex? What common compensatory movement patterns would be visible in the transverse plane and which adductor muscles would be the cause of this?

Answer:

In order to answer your question as thoroughly as possible, I have broken the question down into three parts. First I want to address muscle action. The adductor complex is quite complex. Each muscle within the complex has a unified purpose, but works individually within different ranges of motion and different planes of motion. So far, no one is able to agree on exactly how the adductors function. At NASM, we have chosen to look at the adductor complex from a mechanical standpoint. Considering the origin and insertion of each particular muscle and its integrated function in different planes of motion, we have tried to break down each muscles’ action as simply as possible. The following table lists each muscle’s origin and insertion as well as the muscles’ function in each plane.

In response to the second part of your question, normal gait requires that the adductors function as neutralizers. Their job is to control unwanted action when a person is moving in the sagittal plane. The adductors work in conjunction with the abductors so that there is no frontal plane movement. During stance, the adductors act as stabilizers. Their function is to stabilize the lumbo-pelvic-hip complex. Only during specific movement patterns, such as kicking a soccer ball or cutting across your body, are the adductors performing a specific concentric action. However, each action within the body requires inter-muscular coordination. There is no true isolation of muscles because the nervous system recruits muscles in synergies. Based on this, it is hard to decipher exactly what muscles would be prone to lengthening or shortening because it would require an assessment of what other imbalances are present.

Muscle imbalances are very individualized. We cannot say that specific muscles within the complex are more prone to shortening or lengthening because of their integrated function. For example, if the leg is in an abducted position, the adductor magnus will kick in to adduct the leg because mechanically it is in the best position. But, after the leg crosses the iliac crest, the pectineus and adductor brevis will begin to dominate the motion. So, each adductor has a primary, secondary and tertiary function and each has an integrated purpose. So, it would be too difficult to differentiate one muscle within the complex being more susceptible to lengthening or shortening more than another. In reference to your last question, compensatory movement patterns in the transverse plane might involve the adductor complex, but the adductors would not be the cause of compensation. The cause might involve another imbalance someplace elsewhere in the chain. Remember, tightness and weakness work together. If one joint has altered kinematics, this will affect the whole chain. Therefore, one might see a compensation of increased femoral internal rotation in the transverse plane, but again the cause would not necessarily be the adductor complex being lengthened or shortened. A complete kinetic chain assessment would have to be done to find the root of the compensation.