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 some people at least, the answer is a qualified yes. The study, which looked at men at high risk for type 2 diabetes, found that those who exercised in the afternoon improved their metabolic health far better than those who did the same exercise earlier in the day. The results add to the growing evidence that as we exercise, our benefits from this exercise can change.
Scientists have known for some time that the chronology of our days affects the quality of our health. Studies in animals and humans show that every tissue in our body contains a kind of molecular clock that rings in part in response to biological messages related to our daily exposure to light, food, and sleep.
These cellular clocks then aid in calibration as our cells divide, fuel, express genes, and otherwise do their normal biological work. These clocks are tailored to our lifestyle and create multiple circadian rhythms in us that cause body temperatures, hormone levels, blood sugar, blood pressure, muscle strength and other biological systems to dip and rise throughout the day.
Circadian science also shows that disrupting normal circadian patterns can affect our health within 24 hours. For example, people who work overnight and whose sleep habits are changed are at high risk of metabolic problems such as obesity and type 2 diabetes. The same applies to people who eat late in the evening outside of normal meal times. However, more encouraging research suggests that manipulating the timing of sleep and meals can improve metabolic health.
However, much of this research has focused on when we eat or go to bed. Whether and how the timing of exercise might affect metabolic health was less clear, and the results of previous experiments did not always agree. Some suggest doing morning workouts for example enhance fat burning and weight loss.
However, these experiments often manipulated the timing of breakfast and other meals, as well as exercise, making it difficult to filter out the specific circadian effects of exercise. As a rule, healthy volunteers without metabolic problems were also involved.
A much discussed study from 2019On the other hand, men with type 2 diabetes found that they significantly improved their blood sugar control after two weeks if they did intense interval sessions for a few minutes in the afternoon. However, when they did the same intense workouts in the morning, their blood sugar levels actually rose in unhealthy ways.
Patrick Schrauwen, Professor of Nutrition and Exercise Sciences at Maastricht University Medical Center in the Netherlands, read this 2019 study with interest. He and his colleagues had studied moderate exercise in people with type 2 diabetes, but their research ignored the possible role of timing. Now, seeing the different effects of the intense workouts, he wondered if the timing of moderate workouts could also affect how the workouts changed people’s metabolism.
Fortunately, he and his colleagues had a prepackaged data source in their own previous experiment. A few years earlier, they asked adult men at high risk for type 2 diabetes to ride stationary bikes in the lab three times a week for 12 weeks while the researchers tracked their metabolic health. By the way, the scientists had also noticed when the drivers showed up for their training.
Now Dr. Schrauwen and his colleagues recorded data for the 12 men who had exercised regularly between 8 and 10 a.m. and compared them with a further 20 who always trained between 3 and 6 p.m. They found that the benefits of the afternoon exercise significantly outweighed the benefits of the morning exercise.
After 12 weeks, the men who pedaled in the afternoon showed significantly better average insulin sensitivity than the morning trainers, resulting in a better ability to control blood sugar. They had also lost a little more fat from their midst than the morning riders, even though all of the training routines were identical.
“I believe that it is better to exercise than not to exercise, regardless of the timing,” says Dr. Schrauwen. “However, this study suggests that afternoon exercise may be more beneficial for people with metabolic disorders” than the same exercise that was done previously.
However, the study in Physiological Reports only included men. Women’s metabolism can react differently.
The researchers also didn’t investigate why the later workouts might affect metabolism differently than earlier ones. Dr. However, Schrauwen believes that moderate afternoon exercise can have an impact on the foods we consume later in the evening and “can help metabolize people’s last meals faster” before they go to sleep. This effect could leave our body in an sober state overnight, which allows body clocks and metabolism to be better synchronized and health refined.
He and his colleagues hope to examine the underlying molecular effects in future studies and whether the timing of lunch and dinner changes these results. The team also hopes to investigate whether evening workouts can amplify, or possibly undercut, the benefits of afternoon exertion by worsening sleep.
Ultimately, according to Dr. Schrauwen, the training program that is particularly effective for each of us will match “our daily routines” and training inclinations. Because exercise is good for us at any time of the day – but only if we choose to keep going.