"It is easy to catch a cold after strenuous exercise." This is not a coincidence, but a scientific basis. A large number of studies show that during high-intensity training or competitive competition, the risk of respiratory tract infection of athletes increases. The relationship between exercise and the incidence of upper respiratory tract infection is J-shaped curve, that is, the incidence of upper respiratory tract infection decreases during moderate exercise and increases during excessive exercise. After intensive exercise, the body will have a "window opening period" ranging from 3 hours to 72 hours. During this period, the immune function of the body will be weakened, and the risk of various pathogenic factors, especially viruses, entering the host will increase.

So what is moderate exercise intensity? We can take the subjective feeling of fatigue as the standard, or calculate the intensity of exercise by measuring the heart rate. The heart rate during exercise is equal to the number of pulses per minute during exercise. Count your pulse number 10 second immediately after exercise, and multiply it by 6, which is the heart rate value. The heart rate during moderate intensity exercise is generally about 60% to 70% of the maximum heart rate, and the maximum heart rate =220- age.

The length should be appropriate.

The duration of exercise is 20 to 90 minutes. Too short exercise time stimulates the immune system and cardiopulmonary system, while too long exercise time is easy to cause excessive fatigue, which is not conducive to the elimination of fatigue after exercise and the recovery of physical function.

Choose the right type

A certain intensity of aerobic exercise and strength training can enhance immune function. Young people can choose the methods of strength training for large muscle groups, such as squat exercises and abdominal back muscle strength training. Strengthening the training of lower limb muscles, gluteal muscles and low back muscles can not only enhance immunity, but also improve the function of low back muscles and prevent neck and waist strain caused by sedentary and less exercise. Middle-aged and elderly people can choose Tai Ji Chuan, square dance, brisk walking and other moderate-intensity aerobic exercises.

Matters needing attention

Some people may be accompanied by heart disease, high blood pressure, musculoskeletal pain and other problems. Therefore, we should pay attention to the principles of safety, individuality and scientificity when exercising. According to your own situation, exercise step by step, try to take off your mask when exercising at home, and monitor the changes of heart rate and blood pressure. And pay attention to the correct way of action to avoid sports injuries caused by wrong actions and wrong force.