This dual functionality explains why the muscle is so massive. It must possess the endurance to maintain postural stability against gravity and the explosive power to contribute to athletic movements like sprinting and jumping. In many ways, the adductor magnus is the keystone of the lower extremity, seamlessly blending the roles of adduction and extension into a single, fluid motion.
However, the adductor magnus is far more than a simple stabilizer. Its posterior fibers, with their vertical orientation from the ischial tuberosity to the femur, are in a prime position to perform a role typically attributed to the hamstrings: hip extension. When the hip is flexed, such as during the stance phase of running or climbing stairs, the posterior fibers of the adductor magnus powerfully extend the femur, driving the body upward and forward. In this capacity, the muscle acts as a critical extensor, a "fourth hamstring" that supplements the work of the biceps femoris, semitendinosus, and semimembranosus. adductor magnus