In the science and practice of strength training it is sometimes suggested that the deep squat entails an increased injury risk of the lumbar spine and the knee joint. Avoiding deep flexion is believed to minimize the magnitude of knee joint forces. Because within the first 50° of knee flexion calculated retropatellar compressive stress is lower, execution of quarter or half squats is recommended when overuse injuries and degenerative changes of the patella-tendon-complex exist.