Give an example of an isometric strengthening exercise for the knee.

• A. Leg extensions
• B. Quad sets (quad isometrics) performed with the leg extended and knee relaxed.
• C. Stationary bike
• D. Hamstring curls

Answer: (B)

Isometric strengthening means generating force without moving the joint. For the knee, a quad set does this by contracting the quadriceps while the knee stays still—usually with the leg straight and the back of the knee pressed lightly against a surface or simply held tight without bending. This keeps the muscle active and helps maintain strength and knee stability without stressing the joint, making it a common early rehab exercise after knee injuries.

The other options involve movement at the knee. Leg extensions bend and straighten the knee against resistance (dynamic), a stationary bike requires ongoing knee bending and pushing of pedals, and hamstring curls involve knee flexion with movement. So they’re not isometric.