The pros and cons of morning exercise: key factors for dieters to know

II. Of all the days, the morning is the most important, while midday and evening are also suitable.

Although there is an ancient Chinese saying about getting up at the crowing of the rooster to practice martial arts, from the perspective of sports medicine, early morning is not the best time to exercise. This is especially true for people with respiratory diseases, high blood pressure, or coronary heart disease.

As the saying goes, "The early bird catches the worm." In the hazy morning light, lakesides, parks, and tree-lined paths are filled with people exercising. Many people enjoy exercising in the early morning for the following reasons:

(1) Because the air is fresh in the early morning, exercising in the early morning helps to expel carbon dioxide from the body and inhale more oxygen, which is beneficial to strengthening the body's metabolism and improving the effect of exercise.

(2) After waking up in the morning, the cerebral cortex is in an inhibited state. Through a certain period of exercise, the excitability of the cerebral cortex can be moderately increased, which is beneficial to the study and work of the day. Most people who regularly participate in exercise will have this experience: if they do not exercise in the morning, they will feel listless and unable to muster energy all day.

(3) When exercising in the morning, the cool air stimulates the respiratory mucosa, which can enhance the body's resistance to adapt to changes in the external environment and make it less likely to catch a cold or other illnesses. Therefore, some people say that a little exercise in the morning can prevent illness.

(4) The fundamental principle of exercise for weight loss is to enhance metabolism and consume more energy. After each aerobic exercise session, the body's metabolic rate increases and remains elevated for several hours. Accumulated fat is also consumed during this time, thus achieving weight loss. Metabolism is at its lowest point in the morning and peaks in the evening. Engaging in aerobic exercise immediately after waking up in the morning can raise the metabolic rate earlier, keeping it at a higher level throughout the day, resulting in more energy and increased energy expenditure, which is beneficial for weight loss.

However, from a medical and health perspective, early morning is not the best time to exercise. The main reasons are:

(1) From the perspective of natural laws, plants absorb oxygen and release carbon dioxide at night. In the early morning, when the sun is just rising, the photosynthesis of plants has just begun. There is relatively little oxygen in the air and a high concentration of carbon dioxide. If you exercise earlier, the effect will be worse. In large and medium-sized cities, the atmospheric activity is relatively still in the early morning, and various waste gases (domestic gas and industrial gas) are not easy to dissipate. It is the time of day with more serious air pollution.

(2) From the perspective of the physiological changes in the human body, after a night's sleep, the body loses water through respiration, skin, and excrement. This results in a water deficit, leaving all tissues, organs, and even cells in a state of relative dehydration. When the body's hydration is poor, the blood viscosity increases due to reduced circulating blood volume. In mild cases, this can affect the speed of blood circulation throughout the body, failing to meet the body's blood and oxygen supply needs for muscle tissue during exercise, thus easily leading to increased heart rate, palpitations, shortness of breath, and elevated body temperature during exercise. In severe cases, especially when the body has pre-existing medical conditions, a sudden transition from a resting state to strenuous exercise can easily induce thrombosis and myocardial infarction.