In the fitness exercise, there are several reasons for knee pain. 1, when you first start fitness exercise, the usual muscle ligament tension and fitness tension is not the same, resulting in tendon strain, pain. 2, before the fitness did not do a good job of warming up activities, in the fitness due to the power suddenly become large, resulting in muscle strain, pain. 3, long-term fitness. Overload, that is, too much exercise, the resulting strain and injury, it is recommended that under the guidance of a professional fitness coach, sports fitness. Fitness before a good warm-up activities, discomfort, to immediately stop for rest. So the cycle, adhere to the exercise, this symptom will be improved.