Warm-up is a problem that people often ignore in training. Warm-up and preparation activities should be fully carried out. In practical work, we find that many sports injuries are caused by insufficient warm-up activities. Therefore, it is necessary to prepare for the training. Warm-up activities can improve the excitability of the central nervous system, overcome the physiological inertia of physical function activities and prepare for formal exercise. Warm-up activities can increase the number of open capillaries in muscles, improve the strength, elasticity and flexibility of muscles, improve the function of joint ligaments, enhance the elasticity of ligaments, increase synovial fluid in joint cavities, and prevent the injury of muscles and ligaments.