How long is the best time to do aerobic exercise?

For the vast majority of healthy adults, a single session of 20 to 60 minutes and a total of 150 minutes of moderate-intensity aerobics per week, or 75 minutes of high-intensity aerobics, is the option with the highest input-output ratio. The specific duration depends on your exercise goals, physical tolerance, and current life rhythm.

I encountered this pitfall when I first started working out. I believed the nonsense on the Internet that "aerobic exercise must last for more than 40 minutes to burn fat." I ran 10 laps around the playground every day after get off work for exactly one hour. After half a month, the inner side of my knees hurt so much that I could tremble when I walked down the stairs. I didn't lose much body fat, but my bench press weight dropped by 5 kilograms. Later, when I talked with the coach, I found out that I was in the muscle-building phase at that time. Long-term medium-to-high-intensity aerobics consumed all my muscles and lowered my basal metabolism. What's even more ridiculous is that the statement "only consume sugar in the first 30 minutes and burn fat later" is simply untenable. From the first minute you open your legs, sugar and fat are already supplying energy together. It's just that the proportion of fat energy supply will be higher by a few percentage points after 30 minutes. You can't stay up for this difference, but it will hurt your body.

In fact, the aerobic duration requirements of different sports groups are quite different. Veterans in the bodybuilding circle basically limit aerobic exercise to less than 30 minutes, either doing 20 minutes of low-intensity elliptical training after warming up, or doing 10 minutes of interval running after strength training, for fear of consuming the hard-earned muscles. This statement is not unfounded. Research on exercise physiology does show that when the aerobic duration exceeds 60 minutes and the intensity is maintained at more than 65% of the maximum heart rate, cortisol levels will increase significantly, and the rate of muscle decomposition will indeed accelerate. However, this premise is that your own muscle mass is not low and you do resistance training regularly. If you are an ordinary person who does not touch dumbbells at all, there is no need to worry about losing muscle.

If you are just trying to lose weight and maintain health, there is no need to be so stuck. I once had a colleague who weighed 160 pounds and wanted to lose weight. He started doing aerobics with the blogger for an hour and a half every day. After a week of dancing, his ankle sprained, so my aunt postponed it for 10 days. Later, I adjusted to walking briskly for 35 minutes downstairs after dinner every day, and riding a bicycle in the suburbs for an hour on weekends. This did not require me to squeeze in time to change into sportswear, nor would it affect my work the next day. I steadily lost 20 pounds in more than three months, and there was no rebound. You see, it doesn’t even meet the 40-minute threshold, and the effect is just as good. The so-called moderate intensity is easy to judge. It means that you can talk normally when exercising, but cannot sing coherently. The heart rate should be between 60% and 70% of (220-age).

There is also a very popular "fragmented aerobics" school. The core idea is to do 10 minutes of moderate-intensity exercise every time, 3 times a day, and the health benefits are almost the same as a single continuous 30 minutes. It is especially suitable for office workers who are too busy to squeeze out a whole block of time: get off the subway two stops in the morning and walk for 10 minutes, walk around the company campus for 10 minutes after lunch, and take an extra 10 minutes to pick up the express delivery after get off work. The aerobic volume for the day is enough, and there is no need to force yourself to set aside an hour to go to the gym. Instead, it is easy to give up simply because you cannot achieve your goals.

Of course, many people disagree with this statement, especially endurance enthusiasts who compete in marathons and triathlons. Their logic is that in order to increase their maximum oxygen uptake and lactate resistance threshold, they must have steady-state aerobic training for more than 45 minutes, otherwise they will not meet the competition preparation requirements. This is absolutely fine. Of course, the standards will be different for different goals. It is common for marathon enthusiasts I know to do long distances for two hours a day during their preparations. Their bodies have already established a tolerance, and there will be no problems with cortisol spikes or muscle loss. Instead, their cardiorespiratory abilities are getting better and better.

As for middle-aged and elderly friends with high blood pressure and heart disease, the priorities are even different. Don't impose any time limit. Stop exercising after about 20 minutes each time. Control your heart rate within (170-age). If you feel a little breathless but can still communicate normally, stop and rest immediately if you feel uncomfortable. Even if you walk a few more times a day, safety is always more important than "reaching the standard."

In fact, is there any “best” time length? If you have a good rest today and feel refreshed by running for 20 minutes more, that’s totally fine. ； If you are so tired from working overtime today that you just want to lie down, going downstairs for a 10-minute walk is better than lying down. Those who insist that they must practice for a certain number of minutes to be useful are either selling courses to create anxiety, or they have not actually practiced for a few days at all. The best time is the one that suits you, can be sustained for a long time, and does not cause additional burden on the body.