In a closed-chain knee exercise, at what angle is the knee strongest?

• A. 135 Degrees of Flexion
• B. 0 Degrees of Extension
• C. 45 Degrees of Flexion
• D. 90 Degrees of Flexion

Answer: (B)

In a closed-chain knee exercise the joint’s load-bearing and stability are greatest when the knee is near full extension. This position provides maximum joint stability because the ligaments are taut and the bony surfaces are well congruent, helping resist unwanted tibial movement and allowing force to be transmitted efficiently through the leg. With the foot planted, the leg acts as a stiff lever, so the surrounding muscles can work together to handle higher external loads. At more flexed angles, stability relies more on muscle activation and the joint mechanics change, which reduces the maximal load the knee can safely handle in a closed-chain task. So the knee is strongest when it’s nearly straight.