How long is the most effective duration of aerobic exercise?

Judging from the mainstream needs of ordinary bodybuilders to lose fat and improve their cardiopulmonary fitness, the golden range of effective aerobic exercise for a single session is 20 to 60 minutes. You don’t need to do it for more than an hour, and don’t think that training in less than half an hour is in vain.

Xiao Zhou, an office worker I took care of, used to be a typical patient with time anxiety. At first, she always said that she could not squeeze in an hour to exercise. She could only walk around the neighborhood for 15 minutes after get off work. She always felt that these ten minutes were useless and gave up after walking for two days. Later, I asked her not to worry about the whole time. I got off the bus two stops early in the morning and walked briskly for 20 minutes, and then walked around the neighborhood for 15 minutes after get off work. I kept it at a moderate intensity where I could talk normally but couldn't sing loudly. I lost 4 pounds in three weeks, and my body fat rate dropped by 1.2%. Even my previous problem of panting while climbing the third floor was much better.

However, there have always been different opinions on the duration of aerobic exercise. In the past few years, the saying "You must practice continuously for 30 minutes to burn fat" was particularly popular on the Internet. In the past two years, many people have said that the effect of fragmented aerobics is the same as that of continuous exercise. The two sides have been arguing. In fact, both opinions have basis, but the applicable scenarios are different.

The saying "burning fat only takes 30 minutes" is actually a misunderstanding of the energy supply ratio. Fat has already participated in energy supply since the first minute of exercise. However, glycogen energy supply accounts for a higher proportion in the first 20 minutes or so. After 20 minutes, the energy supply ratio of fat will gradually rise to a peak. This peak can be maintained for about 60 minutes. If it exceeds 60 minutes, the body's cortisol secretion will increase significantly, which will accelerate muscle decomposition. For ordinary bodybuilders, the gain outweighs the gain.

The idea of fragmented aerobics is not groundless. Last year, the ACSM (American College of Sports Medicine) updated exercise guidelines clearly mentioned that more than 10 minutes of moderate-intensity aerobics each time, which is enough for 30 minutes in a day, is almost the same as the cardiopulmonary improvement effect of 30 minutes of one-time training. If you are really 996, you can squeeze in the entire 20 minutes. If you don’t go out, you can break the exercise into fragments throughout the day, such as climbing stairs for 10 minutes in the morning, walking around the park for 10 minutes after lunch, and riding a shared bicycle for 10 minutes after get off work. The effect is not bad at all, just like you don’t need to eat all the food for the day in one meal. You can still be full by eating in several meals. It is much better than not exercising at all because you can’t make up the whole time.

Of course, if you are an enthusiast preparing for marathons or triathlons, it is routine to do aerobic exercise for 90 minutes or even 2 hours. After all, your core need is to improve long-distance endurance, which is different from the demands of ordinary bodybuilders, and you do not need to follow ordinary people's standards.

To be honest, we ordinary people don’t need to stick to the number of hours when exercising. Rather than worrying about whether we practiced for 20 or 40 minutes today, we can maintain the frequency of exercise 3 to 5 times a week, which is much more useful than training hard for 2 hours at a time and then lying down for a week.