What is the best time of day to exercise? Your gender may be a factor.

There is no wrong time to exercise, but there may be more right times than others.

The best time of day to exercise may depend on your gender and even whether you want to burn fat or get stronger, according to a helpful new study on men, women and the timing of exercise.

He found that for women, morning workouts shed belly fat and improved blood pressure better than late-night workouts. For men, nighttime exercise led to greater fat burning and better blood pressure control. Night exercise also amplified the benefits of strength training, but more so for women.

Studies of exercise timing are part of the growing science of chronobiology, which focuses on how our internal clocks affect nearly every aspect of our physiology.

Human bodies, like those of other mammals, plants, reptiles and insects, operate on an innate 24-hour circadian rhythm, with a master clock system in our brain that sends and receives biochemical signals that coordinate with molecular clocks within our cells to direct an impact. symphony of biological processes.

This rhythm, in turn, responds to signals from the outside world, especially daylight and darkness, but also when we eat, sleep and exercise.

Recent studies in mice allowed large groups of rodents to run on exercise wheels at different times of the day. Studies have shown that animals’ heart rate, fat burning, gene expression and body weight change substantially depending on when they exercise, even if the exercise itself is the same.

However, human studies on exercise time have been more conflicting. Some show that people burn extra fat and lose more weight by exercising early, especially before breakfast, while others suggest that we get greater health benefits from workouts in the afternoon or evening.

But most of these studies were small and only included men with metabolic conditions, such as type 2 diabetes, high blood pressure or obesity. So we know little about the optimal time to exercise for healthy men, and even less about the best time for women. That’s why the new study is so significant.

A real-world study of exercise time

Published in May in Frontiers in Physiology, the research was designed to reflect real-world demographics, said Paul Arciero, director of the Human Nutrition, Performance and Metabolism Laboratory at Skidmore College in Saratoga Springs, N.Y., and lead author of the study

All volunteers identified as either male or female, and more than half of the 56 participants were female. They were also all healthy and physically active, but not athletes.

The researchers tested the health, strength and fitness of the volunteers, then randomly divided them into two groups, with equal numbers of men and women. One group was asked to exercise four times a week in the morning, between 6am and 8am.

Each group participated in identical training. Once a week, they lifted weights. The next day, they did about 35 minutes of interval training (running, swimming or cycling as hard as possible for about a minute, resting and repeating). Another day, they did yoga or Pilates. They ended the week with about an hour of running, cycling, or other aerobic exercise.

The groups maintained this routine for 12 weeks, then returned to the lab to be tested again.

Everyone in the studio was leaner, faster, fitter, stronger, healthier and more flexible, whether they trained early or late.

Do you want to lose belly fat? Or increase strength?

But there were significant differences between the groups based on the time of day they exercised. Here’s what the researchers found:

  • For women, fat burns best in the morning. The early women lost, on average, about 3% more total body fat than the evening exercisers, with much of the loss coming from the waist. People who exercise in the morning lose about 7% more abdominal fat than women who exercise in the evening. (None of the volunteers’ total body weight fell, as they gained muscle as they lost fat.)
  • Morning exercise also reduced blood pressure in female athletes significantly better than the same evening workouts.
  • Meanwhile, women’s nighttime exercise increased strength gains. Overall, the night athletes improved their upper body strength by 7 percent more than the morning group, and they also did more sit-ups and push-ups.
  • For men, nighttime exercise was the clear winner in terms of health. Those who exercised in the evening significantly reduced their cholesterol levels, while those who exercised in the morning, surprisingly, slightly increased theirs. Evening exercise also led to fat burning in men. At the end of the study, the bodies of the men who exercised at night burned 28% more fat during the workouts than at the beginning, a change that can lead to loss of body fat. Fat burning in the morning group grew only slightly.
  • However, any time was the right time for men to increase their strength and fitness. Among men, morning and evening athletes increased their bench press, leg press, squat, push-up, and other strength improvements to about the same extent whether they exercised early or late .

What these results mean in practical terms is that women with specific health or fitness goals may want to fine-tune the timing of their workouts, Arciero said. If you’re a woman hoping to lose inches around your middle, consider morning workouts. If your goal is strength, night workouts may be more effective.

For men, exercising early or late seems comparable for strength and fitness, but exercising at night could have special health benefits, Arciero said.

Still, “it’s still early days in terms of providing individualized prescriptions for the optimal time of day to exercise,” said John Hawley, head of the Exercise and Nutrition Research Program at the Australian Catholic University in Melbourne. , Australia, who has done a great job. studied metabolism and exercise timing, but did not participate in this study.

He noted that the new study did not control for women’s menstrual cycles or track people’s chronotypes, whether they were naturally morning or evening people, both of which could influence exercise responses. It also did not include midday exercise or look at why men and women reacted so differently to the timing of exercise. Arciero suspects hormones and other cellular and genetic effects, and plans follow-up studies to learn more, he said.

For now, the key takeaway from the study is that time can adjust what we gain from exercise. But we benefit regardless, so “any time of day you choose to exercise is a good time,” Hawley said.

Have a fitness question? e-mail [email protected] and we can answer your question in a future column.

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