Some people get up at 4 o'clock in the morning to run and do morning exercises because of work. Do morning exercises so early? Generally speaking, the air in the morning is particularly fresh and clean, and doing morning exercises at this time is of great benefit to human health, but this is not absolute, not to say that the sooner you exercise, the better. We know that the air is fresh in the morning because there are few cars and people's activities at that time, and the atmosphere on the earth's surface is relatively static; On the other hand, at dawn, plants begin to carry out photosynthesis, absorbing carbon dioxide and releasing oxygen. However, if you start exercising at 4 o'clock in the morning, plants will absorb oxygen and release carbon dioxide without sunlight, which is not very hygienic. In addition, if you are in poor spirits because of poor eyesight, bad weather, uneven road surface and poor rest, it will also cause accidents. We found that some middle-aged and elderly people will have nausea, dizziness and chest pain when practicing boxing at 4 am. So, when should we start morning exercises? This varies from person to person, from place to place and from season to season. Generally speaking, it is better to do morning exercises at five or six in summer and at six or seven in winter.