Which exercise is considered an open chain exercise?

An open chain exercise is characterized by the movement of the distal end of the limb being free to move, which generally allows for greater isolation of specific muscle groups and joint movement. In the context of the options provided, a bicep curl involves the elbow flexing and extending while the forearm and wrist move through space, allowing for the hand to move independently. This distinct movement pattern is a hallmark of an open chain exercise.

In contrast, squats and deadlifts are classified as closed chain exercises because the feet are fixed to the ground, which incorporates multiple joints and muscle groups working together and leads to compound movements. The leg press shares this closed chain characteristic since it involves pushing against a platform, with feet stabilized in place. Thus, the bicep curl stands out as the correct representation of an open chain exercise, focusing on isolated muscle engagement and joint movement.