The semimembranosus is located to the rear of the upper leg, and along with the biceps femoris and semitendinosus collectively form the hamstrings.
The hamstrings are actively engaged during exercises such as the standing leg curl which involve the flexion of the leg. Another important role the hamstrings has is the extension of the hip, which therefore offers another avenue for development with exercises such as the stiff leg deadlift, clean, and traditional deadlift.
The development of the hamstrings (coupled with strengthening of the knee extenders) is particularly important for a stable knee joint. Strong hamstrings can reduce the stress and injury risk to ligaments during dynamic sporting activities.