Is it better for our body to exercise at certain times of the day?
A new and useful study on exercise schedule and metabolic health suggests that, at least for some people, the answer is a yes with reservations. The study, which looked at men at high risk for type 2 diabetes, found that those who performed workouts in the afternoon they improved their metabolic health much more than those who performed the same exercise in the early hours of the day. The results add up to more tests than the moment we exercise can alter their benefits.
Scientists have long known that the chronology of our days influences the quality of our health. Studies in both animals and humans indicate that all tissues in our body contain a kind of molecular clock that sounds, in part, in response to biological messages related to our daily exposure to light, food and sleep.
These cellular clocks help to calibrate the moment our cells divide, refuel, express genes, and do their normal biological work. Adjusted for our lifestyle, these watches create multiple circadian rhythms inside us that cause our body temperature, hormone levels, blood sugar, blood pressure, muscle strength and other biological systems to have highs and lows. throughout the day.
Circadian science also shows that altering normal 24-hour circadian patterns can harm our health. People who work night shifts, for example, sleep habits are altered, tend to have a high risk of metabolic problems such as obesity and type 2 diabetes. The same goes for people who eat late at night, outside the usual dinner hours. However, more encouraging research suggests that manipulating sleep and meal schedules can improve metabolic health.
But a lot of this research focuses on when we eat or go to bed. It is not so clear whether exercise schedule can influence metabolic health, nor in what way, and the results of the experiments performed do not always match. Some suggest that morning workouts, for example, increase fat burning and weight loss.
But these experiments often manipulate the schedule of breakfast and other meals, as well as that of exercise, which makes it difficult to determine the specific circadian effects of training. Healthy volunteers with no metabolic problems also tend to participate.
On the other hand, a much-discussed 2019 study found that men with type 2 diabetes who performed a few minutes of high-intensity interval sessions in the afternoon substantially improved their blood glucose control in the head. of two weeks. However, if they did the same intense workouts in the morning, their blood sugar levels would actually skyrocket in an unhealthy way.
Patrick Schrauwen, professor of nutrition and movement sciences at the Medical Center of the University of Maastricht (Netherlands), read this 2019 study with interest. He and his colleagues had studied moderate exercise in people with type 2 diabetes, but in their research they had not considered the possible role of the schedule. Now, seeing the different effects of intense workouts, he wondered if the timing of moderate workouts could equally affect the way workouts changed people’s metabolism.
Fortunately, he and his colleagues had a data source already prepared, in their own previous experiment. Several years earlier, they had asked high-risk adult men with type 2 diabetes to pedal to the fixed bike in the lab three times a week, for 12 weeks, while researchers monitored their metabolic health. By the way, scientists had also noted at what point patients showed up for their workouts.
Then, Schrauwen and colleagues extracted data from the 12 men who exercised systematically between 8 and 10 a.m. and compared them to another 20 who always exercised between 3 and 6 p.m.
After 12 weeks, men who had cycled in the afternoon showed a significantly higher average insulin sensitivity than those who exercised in the morning, which resulted in a greater ability to control blood sugar. They had also lost a little more waist fat than those who pedaled in the morning, even though everyone’s exercise routines had been identical.
“I think exercising is better than not doing it, regardless of the moment,” Schrauwen says. “However, this study suggests that afternoon exercise may be more beneficial” for people with altered metabolisms than the same exercise performed before.
However, in the study, published in Physiological reports, Only men participated. Women’s metabolism might respond differently.
The researchers also did not delve into the reasons why evening workouts could affect metabolism differently than those done earlier. But Schrauwen believes moderate afternoon exercise can have one effect on food which we consume later in the evening and “help metabolize the last meals of the day faster” before bedtime. This effect could leave our bodies fasting overnight, which could better synchronize body clocks and metabolisms, and fine-tune health.
He and his colleagues hope to explore the underlying molecular effects in future studies, as well as whether lunch and dinner time alter these results. The team also hopes to investigate whether the night workouts they could amplify the benefits of evening effort, or perhaps undermine them, by making sleep worse.
In the end, Schrauwen says, the particular and most effective exercise regimen for each of us will fit “our daily routines” and our inclinations for exercise. Because exercise is good for us at any time of the day, but only if we choose to keep doing it.
By Gretchen Reynolds © The New York Times