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 repeated excessive stress. 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 be swollen. Risks and complications: 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 an introduction to centrifugal straight-knee calf drop and centrifugal bent-knee calf 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 use only the injured foot for control in the center of gravity drop movement. ①Stand with one foot on the left foot on the step, keeping the knee straight and the 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, 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 times, change to the other side. 2.Centrifugal knee drop This exercise is different from the previous one in that it exercises the halibut muscle instead of the gastrocnemius muscle, so be careful to use only the injured foot for control in the weight drop movement. ① left foot standing on one foot on the step, knee flexion of about 45 degrees, toes on the step heel overhang, if necessary, use the arms to help maintain balance. ② slowly lower the left heel, keeping 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.