(1) resistance increasing principle

The principle of increasing resistance refers to gradually increasing the exercise load during strength training. With the increase of muscle strength and endurance, the original weight, number of groups and repetitions, interval time and other factors that constitute the exercise load need to be gradually adjusted. When the muscles never adapt to a certain exercise load, the original overload becomes non-overload or low load. At this time, if the load is not increased, the strength and endurance cannot be improved. For example, to increase the endurance of local muscles, it is necessary to gradually reduce the interval between groups or increase the number of training groups and training times. Exercise load should be from small to large, movements from easy to difficult, from simple to complex, and everything should be gradual.

(2) the principle of particularity

The principle of specialization refers to the practice means and methods adopted in practice according to the needs of different sports or the degree of demand for special strength and endurance. In the process of completing exercise, each muscle has its own function, but there is always a muscle group that plays a major role. In order to develop muscles in a certain part independently to the greatest extent, it is necessary to separate the main exertion muscles from other muscle activities as much as possible. For example, strengthening the strength of upper limb biceps brachii alone, bending with both arms is better than pull-ups For another example, in weightlifting practice, using large load and few groups can increase muscle strength and volume, but it can't increase muscle endurance; However, using small load and multi-group exercises can strengthen muscle endurance, but the increase of muscle strength is not obvious.

(3) the principle of regularity

Perseverance and persistence are the most important things to increase muscle strength and endurance through long-term systematic training. The results show that if you don't do proper overload exercise every 72 ~ 96h (3 ~ 4 days), your muscles will become weaker and smaller. After stopping practicing for 30 weeks, the original growth level completely subsided. Strength training once a week can only maintain the original level, twice a week can increase strength, and 3 ~ 4 times a week can obviously increase muscle strength.