Knee Injuries and Disorders

The goal of this clinical trial is to assess the effectiveness of isokinetic rehabilitation training under optimal stiffness in patients undergoing knee joint rehabilitation. The main questions it aims to answer are: * Does isokinetic training under optimal stiffness lead to greater force exertion compared to traditional bodyweight training? * What are the long-term (6-week) effects of isokinetic training under optimal stiffness on joint flexibility and muscle strength? Researchers will compare the effects of isokinetic training under optimal stiffness to traditional bodyweight training to see if isokinetic training produces superior improvements in muscle strength, flexibility, and overall functional recovery. Participants will: * Perform regular training sessions using a portable knee joint isokinetic trainer, customized to their optimal stiffness for maximum force exertion. * Engage in a 6-week rehabilitation program, with assessments at the beginning, and end of the study to evaluate changes in muscle strength, and functional recovery.

Competitive sport increases risk for musculoskeletal injury (e.g., traumatic knee injury) and may position former athletes for early onset of chronic diseases, chronic pain, poor health-related quality of life, and disability. Quantifying function in former athletes with and without a prior injury and non-athlete controls is critical to understanding long-term health trajectories in athletes and informing potential interventional studies. One modifiable factor that may be associated with long-term health in athletes is physical activity patterns. The purpose of this study is to evaluate strength, function, physical activity, dietary patterns, and cardiometabolic health among current and former competitive athletes and in nonathlete controls to evaluate the impact of prior knee injury and sedentary behavior as two potential determinants of later poor health and reduced function.