Achilles tendonitis is a tendon degeneration characterized by pain and swelling that occurs in the Achilles tendon and surrounding tissues on the back of the lower leg. Causes Achilles tendonitis is a fatiguing injury caused by repetitive and excessive stress. It is common in sports that require running and jumping, such as basketball, soccer and volleyball, and is particularly common in middle-aged people. Symptoms and diagnosis The main symptom of Achilles tendonitis is pain, ranging from mild discomfort to severe pain, and the area around the tendon may swell. Risks and complications If left untreated, Achilles tendinitis can lead to tendon degeneration and even minor lacerations, which can cumulatively lead to partial or complete rupture of the Achilles tendon. Rehabilitation Methods The following is a description of centrifugal straight knee drop and centrifugal flexion knee drop, which can be used as a means of rehabilitation for Achilles tendonitis. 1. Centrifugal straight knee drop may cause pain at the beginning of the exercise. This exercise strengthens and lengthens the gastrocnemius muscles, taking care to control only the injured foot during the weight descent. ①Stand with one foot on the left foot on the step, keep the knee straight, toes on the step heel overhang, use your arms to help maintain balance if necessary. ② slowly lower the left heel, feel the Achilles tendon and calf muscles being pulled until the heel is below the level of the step. ③Stand on the step with your right foot and push your body up to the starting position. After completing the scheduled number of reps, switch to the other side. 2. Centrifugal knee drop This exercise differs from the previous one in that it exercises the flounder muscles rather than the gastrocnemius muscles, noting that only the injured foot is used to control the center of gravity during the drop ① Stand on the step with one foot on the left, knee flexed about 45 degrees, toes on the step with the heel hanging in the air, using the arms to help maintain balance if necessary. ② slowly lower the left heel, keep the knee flexed, feel the Achilles tendon and calf muscles being pulled, until the heel is below the step level. ③Stand on the step with your right foot and push your body up to the starting position. After completing the scheduled number of reps, switch to the other side.