Is it better to exercise in the morning or at night? Scientists say it’s best to move first!

Recently, accompanied by the singing of "Compendium of Materia Medica", a new sports craze is emerging. After achieving the initial goal of getting out of bed and exercising, Liu Genghong girls began to move towards a higher-level goal - to achieve higher quality exercise.

So someone raised this question: Is it better to exercise in the morning or in the evening?

Image source: veer

This issue is very complicated, but the scientific community has done a lot of experiments. Let’s take a look at some of the current views!

Part 1

Rat experiments:

Exercise in the morning to control blood sugar, and exercise in the evening to reduce fat

Recently, a study conducted on rats provided a new perspective for discussing the question of whether it is better to exercise in the morning or in the evening [2]. The paper was jointly completed by scientists from multiple countries and published in the journal Cell Metabolism.

In the study, rats were placed in a rotating cage and made to run for an hour before being dissected.

The researchers divided the rats into two groups, one that exercised immediately after waking up in the morning and the other that exercised in the evening before going to bed. In addition, a control group of rats was also set up, in which the rats were housed in similar cages, but the rotating cages were locked so they could not exercise as much as the previous two groups.

The researchers then extracted hundreds of hormones and substances from the rats' blood, muscles, liver, brain, white fat and brown fat cells and measured their levels one by one. In addition, the expression levels of several genes in the rats were evaluated in detail.

What is the result?

The study found that when rats exercised vigorously, hundreds of substances in their bodies changed in sync, regardless of the time of day they exercised. Countless substances in the muscles, liver and fat tissue responded in unison, as if they were coordinating with each other.

So is there no difference in exercising at different times?

No, the types and contents of substances that change do vary in different time periods.

After careful analysis, the researchers found that if the rats exercised immediately after waking up, the biochemical process of burning carbohydrates would be activated, while if the rats exercised before going to sleep, a series of body substances related to burning fat were activated.

Although we cannot completely distinguish between fat metabolism and carbohydrate metabolism, because the two are originally a complementary system in mammals, the results show that a higher level of fat metabolism is beneficial to weight loss, and a higher level of carbohydrate metabolism is beneficial to blood sugar control.

If we correspond to the exercise time, loosely speaking, for rats, exercising after waking up is beneficial for controlling blood sugar, while exercising before going to bed is beneficial for weight loss.

Image source: Reference 2

Although these conclusions were obtained in experimental animals, which have different physiological characteristics from humans, the researchers believe that the metabolic mechanisms observed in both are similar, which also provides clues to explain the different effects of exercise in the morning and evening.

However, in real human experiments, we cannot conduct a full-system analysis of so many indicators as we do for experimental animals, and there seems to be some contradiction between the conclusions of this experiment and similar studies that have already been conducted.

Part 2

Human Experiments:

There is little difference in weight loss between morning and evening exercise

In 2019, an interesting study was conducted in the United States [1]. The researchers recruited 88 obese volunteers (BMI 25 or above) and divided them into four groups to test the relationship between daily exercise time and weight loss in each group.

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Among these four groups, the first group's exercise time was scheduled between 7:00 and 12:00, the second group's exercise time was between 17:00 and 23:00, the third group had free exercise time, and the fourth group did not exercise at all.

After 10 months, the researchers observed significant differences between the four groups. Those who exercised in the morning lost the most weight, while those who exercised in the evening lost slightly less weight. However, the difference between the two was not very large, only about 5%.

Remember the study we mentioned earlier on rats? The difference between the two studies, in addition to the different research subjects, is that they focus directly on different physical data. In the study on rats, the focus was not on body weight, but on blood sugar levels and fatty acid metabolism, not actual body weight indicators.

However, this is not difficult to explain, because the relationship between nutrient metabolism and body weight is complicated. For example, being overweight does not necessarily mean that your blood sugar level is super high. Some people are very thin, but their blood sugar level is very high, while some people look fat and their blood sugar level is relatively low.

Therefore, it is not surprising that there are inconsistent results between studies. It can only be said that the human body is an extremely complex system and our understanding of our own bodies still needs to continue.

Moreover, even in research on weight, it can be seen that the difference in weight loss brought about by exercising in the morning and evening is actually not that great, so everyone should arrange appropriate exercise time according to their own work and schedule.

Part 3

Should we exercise in the morning or in the evening?

According to current research, there is no need to worry about whether to exercise in the morning or in the evening, because multiple evidences have shown that daily exercise is a good habit that increases healthy life expectancy.

At this point, some friends will definitely ask, how long should you exercise? We have done a lot of research on the benefits of exercise. Regular exercise should be at least three times a week, preferably more than five times, and each time lasts about 30 minutes. As for the type of exercise, it doesn't matter.

It should be added that exercise intensity should be adjusted with age to maximize the exercise effect as much as possible.

Image source: veer

Let me tell you a little secret - an indicator to evaluate whether the intensity of exercise is reasonable. That is, our pulse rate during exercise should be approximately 0.6 times of (220-age).

For example, if Mr. Liu is 50 years old this year, then 220 minus 50 equals 170, and multiplying it by 0.6 equals 102, which means that when he exercises, if his pulse reaches 102 beats per minute, he has reached a reasonable exercise intensity. Therefore, the choice of exercise method varies from person to person. For 50-year-old Mr. Liu, walking or other overly gentle exercise may not be the most reasonable exercise method.

In addition, you don’t have to deliberately pursue the duration of each exercise, but you should exercise as many times as possible per week and maintain regular exercise for a long time.

Finally, we can see that whether you exercise in the morning or in the evening, as long as you exercise, you will definitely gain something! So don’t worry about when to exercise, just move!

References:

[1] Willis EA, et al, The effects of exercise session timing on weight loss and components of energy balance: the Midwest exercise trial 2. Int J Obesity, July. 9, 2019.

[2] Sato S, et al., Atlas of exercise metabolism reveals time-dependent signatures of metabolic homeostasis. Cell Metab, Feb 1, 2022.

Produced by: Science Popularization China

Author: Zhang Renmei

Producer: China Science Expo

The article only represents the author's views and does not represent the position of China Science Expo

This article was first published in China Science Expo (kepubolan)

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