Which type of exercises may be safely initiated immediately after knee surgery?

• A. Isometric exercises
• B. Plyometric exercises
• C. High-intensity interval training
• D. Full range of motion dynamic exercises

Answer: (A)

Immediately after knee surgery, the goal is to protect the healing tissues while keeping the leg muscles active. Isometric exercises achieve that by contracting a muscle without moving the knee joint. This means you can activate the quadriceps and other surrounding muscles without placing movement or high loads on the healing structures, reducing the risk of disrupting the repair while still helping to maintain muscle tone, promote circulation, and prevent atrophy. Typical examples are quad sets (tightening the thigh muscle with the knee straight), glute squeezes, hamstring sets, and ankle pumps. These can usually be started very early under clinical guidance and form the safe foundation of early rehab.

Plyometric activities involve explosive movements like jumps, which generate high joint forces and rapid loading—not appropriate right after surgery. High-intensity interval training is too demanding for the healing knee and can stress the repair. Full range of motion dynamic exercises require moving the joint through its range, which can strain healing tissues in the early stages, so they are typically introduced later as healing progresses.