Which muscle is an antagonist during a knee extension?

The biceps femoris plays the role of an antagonist during knee extension because it is a part of the hamstrings group, which functions primarily to flex the knee. During the action of knee extension, the quadriceps group contracts to extend the knee joint. Meanwhile, the hamstrings, including the biceps femoris, must relax to allow this extension to occur effectively. This antagonistic relationship is crucial for smooth movement and proper joint function, as the biceps femoris provides the necessary resistance against the force exerted by the quadriceps. In a nutshell, the biceps femoris and the quadriceps work in opposition during knee extension, establishing a dynamic balance in movement biomechanics.