Recently, a questionnaire survey was conducted among 6000 exercisers in Beijing, Shanghai, Tianjin and Harbin. The results show that 60.8% of the exercisers choose to exercise in the morning. So early morning is the best exercise time? Our investigation began with morning exercises.

At 6: 47 am on February 23, 2006, the reporter drove to Xiangshan Park in Beijing. It was just dawn at this time, and thousands of climbers and morning exercisers had arrived before us. Zhang Yuyang of Xiangshan Park Management Office said: "Xiangshan Park is now the main place for Beijing residents to climb mountains and do morning exercises. There are five or six thousand people who come here for morning exercises every day, and one or two thousand people on weekends. "

Why do China people have a soft spot for morning exercises? Our survey found that an important reason is that people think that exercising in the morning is full of energy, which is beneficial to the work and life of the day. So is it good or bad to choose morning exercise? This involves an extremely complicated problem, that is, the time of life.

The most dangerous moment of a human day is dawn.

People's physiological functions are constantly changing between day and night, so there are always times when they are in poor health and tired, and there are always times when they are healthy and energetic.

The physiological and biochemical activities of most organs in human body have biological clock effect, which is the basic movement trend of human biological clock in a day. A large number of studies have shown that most people's biological clocks are at the peak at 4 pm and just at the lowest ebb at 4 am. In the morning, people's body temperature is the lowest, their pulse is the slowest, and the biological clock oscillation is at a low point. If you start exercising at this time, it is equivalent to suddenly entering strenuous exercise from a rest state. In the eyes of biologists, this is a typical rash move. The joints and muscles of the body change rapidly from relaxation to tension, which is difficult to adapt for a while, and the burden on the cardiovascular system also increases sharply, which is a kind of damage to health. In addition, because the biological clock in the early morning is at the bottom and in the rising and accelerating stage, exercise urges the biological clock to accelerate again, forming a dangerous situation of acceleration. What's more, the sooner you do morning exercises, the better. Some people even get up at three or four in the morning to exercise, and then continue to sleep, which makes the biological clock wrong and worn out, leading to fatigue, disease, premature aging and early death. So morning is not the best time for physical condition at all. The survey shows that the most dangerous moment of the day is dawn. According to the statistics of the World Health Organization, the number of deaths in the early morning accounts for 60% of the total number of deaths in one day. It should be reminded that early morning is extremely dangerous for some patients.

Choosing afternoon exercise is the most scientific.

When is the best time to exercise in a day?

There is a gateball court in the northeast corner of Beijing Youth Lake Park. After 2 pm every day, Li Donghui, a famous Yang-style Tai Ji Chuan player, will come here with his disciples to play Tai Ji Chuan, most of whom are patients with cardiovascular and cerebrovascular diseases. Medical research shows that afternoon exercise is the safest for patients with cardiovascular and cerebrovascular diseases.

What benefits does afternoon exercise have for the health of ordinary people? The latest scientific results confirm that if you choose to exercise in the afternoon, the early gland hormones and cortical hormones in the human body will increase obviously, and the hormones, the key substances of human metabolism, will also be secreted in large quantities, which can promote the energy metabolism of the human body and accelerate the microcirculation in the body exponentially.

We usually lack understanding of the rhythm of the body and don't know how to benefit from it. During the first opening period, the highest point of people's maximum oxygen uptake was around 6 pm; In the morning, the body temperature is generally 35 ~ 36. 1 celsius, and it can rise to 37.4 celsius in the afternoon. The olfactory, visual and tactile parts of the human body are most sensitive from 5 pm to 7 pm; The beating frequency of the heart and the rising speed of blood pressure are also the most stable from 5 pm to 7 pm. In addition, according to the research of British physiologists, the body's stress response ability to the external environment reaches the highest level from 4 pm to 7 pm, and the flexibility of nerves is also the best. If you choose to exercise at the peak of the biological clock in the afternoon, you can give full play to people's potential and physical adaptability, and achieve the purpose of exercise and fitness.

So experts say it is the most scientific to choose afternoon exercise. However, there is another important reason why so many people choose to exercise in the morning, and that is the good air in the morning. What is the truth?

The air quality is the worst in the morning.

We interviewed Zhang Mingying, a famous engineer of Beijing Meteorological Observatory, and the conclusion reached was beyond most people's expectation.

Zhang Mingying said: "The air quality in the morning is the worst, mainly due to the influence of atmospheric stability."

Why does the air remain stable in the morning? This is because the atmosphere has a special inversion phenomenon in the morning.

Inversion is a phenomenon in the atmosphere. We know that when the temperature is normal, it decreases with the increase of height. The inversion phenomenon is just the opposite, and it increases with the increase of height.

The air is warm at the top and cool at the bottom, which causes the vertical convection of the atmosphere to basically stop at night, and the concentration of pollutants near the ground is getting higher and higher, forming a pot cover. In the early morning, we stood on the roof and could clearly see the pot cover formed by pollutants. Unfortunately, it happens to be in the human breathing zone.

Zhang Mingying also said: "The illusion of fresh air in the morning mainly comes from a contrast relationship. At night, people move indoors and exhaust a lot of waste gas, especially in the northern winter, when doors and windows are closed, it is difficult for indoor air to flow. After last night's activities, the indoor air was quite dirty. Therefore, compared with indoor air in the morning, outdoor air is obviously better than indoor air, so people have a feeling that the air in the morning is the freshest. In fact, this is not the case. "

So when is the best air in a day?

Experts replied that the air is cleanest at 2-4 pm every day, because at this time, the surface temperature is the highest, the air is the most active, and pollutants are the easiest to spread.

In order to be confirmed, we invited experts from the Institute of Environmental Health Monitoring, Chinese Academy of Preventive Medicine to conduct on-site air sampling for us. The results are as follows: nitrogen dioxide is 0.050mg/m3 in the morning and 0.0483mg/m3 in the afternoon, sulfur dioxide is 0. 13mg/m3 in the morning and 0. 10mg/m3 in the afternoon. It can be seen from this result that the pollution in the morning is more serious than that in the afternoon.

From the sampling point of view, the air in the afternoon is not much cleaner than that in the morning, but the problem is that the amount of air inhaled during exercise is 3- 10 times as much as usual. Therefore, not only the pollution caused by exercise in the morning is much more serious than that in the afternoon, but also it is likely that exercise is more likely to infect respiratory diseases than no exercise. Combining air cleanliness with human physiological peak, the best exercise time in a day is in the afternoon. However, can a single rule cover the diversity of life? Is afternoon exercise the only choice for us all?