When is the best time to exercise?

What is the best time of day to exercise?

It’s a simple question with a frustrating number of answers, based on research results that can be downright contradictory.

The latest evidence came last month from a group of Australian researchers, who argued that night was the healthiest time to sweat, at least for those who are overweight. Their study looked at 30,000 obese middle-aged people and found that those who exercised at night were 28% less likely to die from any cause than those who exercised in the morning or afternoon.

We were surprised by the gap, said Angelo Sabag, an exercise physiologist at the University of Sydney who led the study. The team expected to see a benefit from night training, but we didn’t think the risk reduction would be as pronounced as it was.

So does this mean that night swimmers and joggers had the right idea all along?

It’s not settled, said Juleen Zierath, a physiologist at the Karolinska Institute in Sweden. It is an emerging research area. We haven’t done all the experiments. We learn a lot every month.

No study can dictate when you should exercise. For many people, the choice comes down to fitness goals, work schedules, and old preferences. That said, certain times of day can offer slight advantages, depending on what you’re hoping to achieve.

The case of morning exercise

Morning exercise may be especially beneficial for heart health, according to a 2022 study. It can also lead to better sleep.

And when it comes to weight loss, there have been good arguments for morning workouts. Last year, a study published in the journal Obesity found that people who exercised between 7am and 9am had a lower body mass index than their counterparts who exercised in the afternoon or at night , although he did not track them over time. unlike the Australian study, which followed participants for an average of eight years.

Of course, the main argument for morning exercise may be purely practical. For many people, the morning is more convenient, said Shawn Youngstedt, professor of exercise science at Arizona State University. Even if getting up early to exercise can be a challenge at first, morning exercise won’t interfere with Zoom meetings, play dates, or your latest Netflix binge.

The case of the afternoon exercise

Some small studies suggest that the best time to train, at least for elite athletes, might be the least convenient for many of us.

Body temperature, which is lower in the morning but rises in the afternoon, plays an important role in sports performance. Several recent studies with competitive athletes suggest that lower body temperatures reduce performance (although warm-up exercises help counteract this) and late afternoon workouts help them play better and sleep longer.

If you have the luxury of enough time, a small New Zealand study found that napping first can help. As for the rest of us, a Chinese study of 92,000 people found that the best time to exercise for your heart was between 11am and 5pm.

The main difference is our population, Dr. Sabag said. While their study was limited to obese people, the Chinese study was not. People with obesity may be more sensitive to the effects of daytime exercise, he said.

The case of night exercise

This latest study may not settle the debate, but it certainly suggests that those struggling with obesity could benefit from a workout afterwards.

Exercise makes insulin more effective at lowering blood sugar levels, which in turn prevents weight gain and type 2 diabetes, a common and devastating consequence of obesity.

In the evening, you’re more insulin resistant, Dr. Sabag said. So if you can compensate for this natural change in insulin sensitivity by exercising, he explained, you can lower blood glucose levels and thereby help keep diabetes and cardiovascular disease at bay.

A persistent concern about nighttime exercise is that vigorous activity can disrupt sleep. However, some experts have argued that these concerns have been overblown.

The case that it may not matter

While many of these studies are fascinating, none of them are definitive. For one thing, most simply show a correlation between exercise times and health benefits, without identifying them as causal.

The ultimate study would be to randomize people at different times, Dr. Youngstedt said, which would be phenomenally expensive and difficult for academics.

One thing public health experts agree on is that most Americans are too sedentary. And that any movement is a good movement.

Whenever you can exercise, urged Dr. Sabag. This is the answer.

In a recent edition of his newsletter discussing the Australian study, bodybuilder, actor and former governor Arnold Schwarzenegger seemed to agree. He cited a 2023 study that suggests there’s really no difference in results based on what time of day you exercise. In this case, it’s about what works best for you.

I will continue to train in the morning, wrote the former Mr. universe It’s automatic for me.

Alexander Nazaryan is a science and culture writer who prefers to run in the early evening.