(1) There are two basic breathing methods: 1. Breathe in when muscles contract hard, and exhale when stretching resumes. 2. Exhale when muscles contract hard and inhale when stretching resumes. These two diametrically opposed ways of breathing. In the practice of the past decades. Many experts have discussed it. But these two breathing methods. Everyone has the same request, that is, to avoid holding your breath for a long time in the process of exertion. (2) Breathing methods commonly used in bodybuilding training; 1, limit or heavy weight, adopt the second breathing method. Take two or three deep breaths before the action begins. Inhale at the beginning of exercise until the "contraction peak" or the exercise is in place, that is, exhale for a very short time, then inhale continuously for a short time until the exercise approaches the previous stage or resumes. 2. Breathing method according to human physiological phenomena: No matter which movement, when the chest ribs and lungs are in an expanded state, use "inhalation" and when the chest ribs and lungs are in a compressed state, use "exhalation". This exhalation method will not cause the lungs to be compressed or hold their breath. 3. In the whole movement process, from the "starting position" to the "ending position", as a breathing method of a breathing unit; It is to "inhale" from the beginning of the action until it returns to the middle stage or "exhale" until the last 1/3 is left. In bodybuilding training, at the beginning of exercise, the active muscles are in the "extended position" or "contracted position". For example, the shoulders, back, arms, front wall, legs and thighs and abdomen during exercise, the "starting position" is mostly that the active muscles are in the "extended position". When exercising the chest, humerus and legs, the "starting position" active muscles are mostly in the "contraction position". But in some cases, the opposite is true. In short, in bodybuilding training, "moderate weight" (generally 85-90%) and multiple times (6- 12 times) are often used instead of "limited weight and few times". Therefore, the phenomenon of "holding your breath" rarely occurs.