The best time to exercise in a day is in the afternoon (14: 00 ~ 16: 00): It is a good opportunity to strengthen physical strength, and muscle endurance is 50% higher than other times. Dusk: (17: 00 ~ 19: 00): Especially when the sun goes down, the human body's exercise ability reaches its peak, and the vision and hearing are more sensitive, and the heart rate and blood pressure also rise. Not suitable for after-meal exercise: at this time, more blood flows to the gastrointestinal department to help food digest and absorb. At this time, exercise will hinder the digestion of food, and over time, it will lead to diseases of the gastrointestinal system and affect health. Therefore, it is best to sit still or lie down for 30 ~ 45 minutes after meals and exercise. After drinking: alcohol is absorbed into the blood and enters the brain, heart, liver and other organs. At this time, exercise will increase the burden on these organs. Compared with after-dinner exercise, drinking exercise has a greater negative impact on the human body. Outdoor fitness is not as early as possible. In the cold winter, many people choose morning exercises to enhance their immunity. However, isn't outdoor fitness the sooner the better? Relevant health experts suggest that outdoor fitness in winter should be carried out after sunrise. It is understood that the ground temperature is low before sunrise in winter, and the content of pollutants such as carbon monoxide and carbon dioxide released in the air in the morning is high. In addition, harmful pollutants such as nitrogen oxides, hydrocarbons and lead in automobile exhaust also gather on the ground. If people get up early to exercise, they will inhale a lot of smoke and toxic gases. Long-term exercise in this environment may lead to fatigue, dizziness, pharyngitis and other diseases, which are harmful to the body. Winter fitness and summer fitness should be around 10. At this time, the sun shines on the ground after coming out, which makes the atmosphere begin to convection up and down, and the polluted air spreads to the sky, which will reduce the harm to the human body. In addition, the temperature is low in winter morning and will not be relieved until half an hour after the sun comes out. Avoid the air pollution peak at six or seven in the morning in the first month or two of winter and spring. In summer and autumn, the sun comes out early and you can exercise at five or six o'clock. Usually, you can choose 10 in the morning, do exercises at 3 or 4 pm or do other sports. At this time, the air is cleaner and more beneficial to health. It is best not to exercise outdoors in foggy mornings. Due to air pollution, fog contains many substances harmful to human body. When people do strenuous activities such as long-distance running in foggy days, some sensitive parts of the body will come into contact with these harmful substances and be inhaled in large quantities, which may easily cause tracheitis, laryngitis, conjunctivitis and allergic diseases. So on foggy mornings, we can do morning exercises indoors instead of going outdoors.