Which is a closed-chain knee exercise?

• A. Leg extensions
• B. Squats
• C. Seated knee flexion
• D. Calf raises

Answer: (B)

The concept tested here is identifying movements where the lower limb works as a closed chain, meaning the foot is fixed to the ground and the body moves as a unit through the joints of the leg. In a squat, your feet stay planted on the floor while your hips and knees bend and straighten and your ankle flexes and extends. This creates a single, integrated chain from the ground up, with force traveling through the whole kinetic chain and requiring coordinated stability across the knee, hip, and ankle.

Leg extensions isolate the knee on a machine with the foot not fixed to the ground, so the movement happens mainly at the knee and is considered open-chain. Seated knee flexion also isolates movement at the knee with the foot not fixed, so it’s open-chain. Calf raises focus on ankle movement and often keep the knee relatively still, so they aren’t primarily a knee-focused closed-chain exercise.

So squats are the best example of a closed-chain knee exercise because the foot is fixed and multiple joints work together in a functional transfer of load.