The muscles you exercise are hard because they are strong. Muscle bears load for a long time, consumes a lot of energy, and has a large oxygen debt, so lactic acid will accumulate in muscle, thus changing the internal environment of muscle, such as lowering blood sugar.

At this time, the working ability of muscles will decline. This is a temporary normal physiological phenomenon, and it is also a reaction of the body's protective inhibition, and it is a "self-defense signal". Arrange the appropriate amount of exercise and the intensity and density of exercise. We should master the ability of muscle relaxation. After each exercise, each group should fully relax their muscles by shaking, taking a deep breath, massaging and taking a hot bath, so as to eliminate fatigue as soon as possible. Grasp the technical essentials correctly, pay attention to coordinate muscle contraction and relaxation, and reduce unnecessary work and consumption.