Is it better for our body to exercise at certain times of the day?
A useful new study on exercise timing and metabolic health suggests that, for at least some people, the answer is one yes with reservation. The study, which analyzed men at high risk for type 2 diabetes, found those who exercised in the afternoon they improved their metabolic health much more than those who did the same exercise first of the day. The results add to the growing body of evidence that the timing of exercise can alter its benefits.
Scientists have long known that the chronology of our days affects the quality of our health. Studies conducted in both animals and humans indicate that all tissues of our body contain some type of molecular clock that rings in part in response to biological messages related to our daily exposure to light, food and sleep.
These cell clocks help measure when our cells divide, feed themselves, express genes, and do their normal biological work. Adjusted by our lifestyle, these clocks create multiple circadian rhythms in us that cause our body temperature, hormone levels, blood sugar, blood pressure, muscle strength and other biological systems to rise and fall during the day.
Circadian science also shows that disrupting normal 24-hour circadian patterns can harm our health. For example, people who work night shifts who have disrupted their sleeping habits often run a high risk of metabolic problems such as obesity and type 2 diabetes. The same is true for people who eat late at night outside normal meal times. However, more encouraging research suggests that manipulating the timing of sleep and meals can improve metabolic health.
But much of this research focuses on when we eat or go to bed. It is not so clear whether the timing of exercise can affect metabolic health, or in what way, and the results of the experiments performed do not always coincide. Some suggest that morning workouts, for example, increase fat burning and weight loss.
But these experiments often manipulate the timing of breakfast and other meals, as well as exercise, making it difficult to determine the specific circadian effects of workouts. Usually healthy volunteers, without metabolic problems, also participate.
On the other hand, a much-discussed 2019 study found that men with type 2 diabetes who did intensive interval sessions in the afternoon for a few minutes had significantly improved blood glucose control within two weeks. However, if they did the same vigorous workouts in the morning, their blood sugar actually rose unhealthy.
Patrick Schrauwen, professor of nutrition and exercise sciences at the Maastricht University Medical Center, the Netherlands, read that study from 2019 with interest. He and his colleagues had studied moderate exercise in people with type 2 diabetes, but had not considered the possible role of schedule in their study. Looking at the different effects of high-intensity workouts, she wondered if the timing of moderate workouts could equally affect how you work workouts changed people’s metabolism.
Fortunately, he and his colleagues had a ready-made data source, in their own previous experiment. Several years earlier, adult men at high risk for type 2 diabetes had been asked to pedal the exercise bike three times a week in the lab for 12 weeks, while the researchers monitored their metabolic health. Incidentally, the scientists had also noticed when patients showed up for their workouts.
Schrauwen and his colleagues then took data from the 12 men who consistently trained between 8 and 10 a.m. and compared them with 20 others who always trained between 3 and 6 p.m.
After 12 weeks, men who cycled in the afternoon had a significantly higher mean insulin sensitivity than those who exercised in the morning, resulting in a increased ability to control blood sugar. They also lost slightly more fat around the waist than those who cycled in the morning, even though everyone’s exercise routines were identical.
“I think exercising is better than not exercising, regardless of the time of day”, says Schrauwen. “However, this study suggests that afternoon exercise may be more beneficial” for women. people with altered metabolism than the same exercise that was done before.
In the study, published in Physiological reports, only men participated. Women’s metabolism can respond differently.
The researchers also did not go into the reasons why evening workouts might affect metabolism differently than earlier. But Schrauwen believes that moderate exercise in the afternoon is one effect on food which we consume later in the evening and “help metabolize the last meals of the day more quickly” before going to bed. This effect could leave our bodies in a state of fasting overnight, something that could better synchronize body clocks and metabolism and improve health.
He and his colleagues hope to investigate the underlying molecular effects in future studies, as well as whether the timing of lunch and dinner changes those results. The team also hopes to investigate whether night workouts They may enhance, or perhaps undermine, the benefits of evening exercise by making sleep worse.
Ultimately, says Schrauwen, the specific and most effective training regimen for each of us will fit “our daily routines” and our tendency to exercise. Because exercise is good for us at any time of the day, but only if we choose to keep doing it.
Por Gretchen Reynolds © The New York Times