Knee osteoarthritis (OA) is a common degenerative joint disease that leads to pain, reduced mobility, and functional limitation. Quadriceps femoris weakness plays a significant role in disease progression and disability. Isotonic strengthening using the N-K Table allows adjustment of load angles to optimize muscle activation; however, the effect of different load angles on quadriceps activation in patients with knee osteoarthritis remains unclear.
This study aims to compare quadriceps femoris activation at 0° and 50° N-K Table load angles in patients with knee osteoarthritis using surface electromyography (sEMG). A randomized cross-over experimental design is applied to determine whether adjusting the load angle improves maximum voluntary contraction (MVC) during isotonic knee extension exercise.