The two main functions of strength training are to increase muscle strength and shape. Anyone with fitness experience will have this experience. At the beginning of fitness, the increase of strength will be earlier than the increase of muscle circumference. The reason is very simple: through resistance strength training, only the increase of muscle strength can ensure the completion of the action, and then through persistent training, muscle fibers will be damaged and repaired continuously, and the muscle cross-sectional area will be increased, so that our muscle volume will increase. Stronger muscles will strengthen people's resistance, so their strength will increase with training.