A concentric contraction of which muscle group would use 'reciprocal inhibition' to stretch the quadriceps?

The correct answer highlights the role of the hamstrings in the process of reciprocal inhibition when attempting to stretch the quadriceps. Reciprocal inhibition is a physiological process where the activation of one muscle group leads to the relaxation of an opposing muscle group.

When a muscle group is contracted, the nervous system sends signals to its antagonist, causing that opposing muscle to relax. In this case, when the hamstrings are activated (either through a concentric contraction or other means), they send inhibitory signals to the quadriceps. This allows the quadriceps to relax and facilitates a more effective stretch of the muscle, thereby easing tension and enhancing flexibility.

Understanding this concept is crucial in the context of physical training, rehabilitation, and flexibility exercises, as it underscores the importance of muscle interactions and proper technique to maximize the benefits of stretching.