Which of the following is an open kinetic chain exercise?

• A. Biceps curl
• B. Step-ups
• C. Lunges
• D. Wall sits

Answer: (A)

Open kinetic chain exercises involve a distal segment that is not fixed to a surface, allowing free movement at the end of a limb. A biceps curl fits this: the hand moves through space as you flex and extend the elbow, with the forearm and hand not anchored to a surface.

In contrast, the other movements keep the feet (or hands) planted or fixed on a surface, creating closed kinetic chain actions. Step-ups, lunges, and wall sits all involve the body moving while the feet stay on the ground or on a platform, engaging multiple joints and stabilizing muscles as a single unit.

Because the biceps curl allows the hand to move freely while the rest of the body remains relatively fixed, it is the open kinetic chain exercise.