FIT is the abbreviation of three English words: frequency, intensity and time. It is the basic monitoring principle that we must adopt when engaging in health-oriented sports. In order to achieve good exercise effect in the process of safe exercise, you must scientifically control the number of exercises per week, the intensity and time of each exercise in physical exercise.

Number of times: indicates a person's cycle, such as the number of physical exercises per week. To get good physical exercise effect, you should do physical exercise at least 3 ~ 5 times a week. As a middle school student whose body is at the peak of growth and development, you should ensure that you do physical exercise five times a week.

Intensity: The intensity control of aerobic exercise can be achieved by measuring the heart rate. In aerobic exercise, the heart rate should be controlled between 60% and 80% of the maximum heart rate. In strength training, the principle of FIT monitoring can be implemented by adjusting the weight of training equipment and the number of exercises. In order to gradually improve your existing physical fitness, you must gradually improve your current exercise intensity after adapting to a certain exercise intensity, that is, complete a gradual process from adaptation to inadaptability and then adaptation.

Time: refers to the duration of each exercise. In order to improve the endurance of cardiopulmonary circulatory system, aerobic exercise should be carried out for at least 20 ~ 30 minutes. The intensity of exercise will directly affect the duration of continuous exercise. In most cases, it is much easier to control the duration of exercise than to control the intensity of exercise.