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What is the best time to exercise?

What is the best time to exercise

Science explains what the ideal time is for physical activity and what to consider when choosing

In July and August, the world’s top athletes will gather in Paris, France, in pursuit of the highest sporting prize on the planet: the Olympic Gold Medal. Those hoping for a chance to break records and enter the annals of sports history may need to glance at the clock before taking their place at the starting line. And one scientific study indicates that this is especially true for swimmers.

In at least four recent Olympic Games—Athens (2004); Beijing (2008); London (2012); and Rio de Janeiro (2016)—the times recorded by the 144 swimming medal winners were better when the competition took place in the late afternoon—specifically, around 5:12 p.m. The study is part of the growing evidence that human physical performance is affected by the time of day.

Endurance sports are particularly susceptible to the effects of time of day. In these sports, performance almost always peaks between 4 p.m. and 8 p.m. The time of day also seems to influence the exercise performance of men and women differently.

Best time to exercise: morning, afternoon or at night?

And what if your schedule indicates that you only have time to exercise at seven in the morning? Well, there are indications that it may be possible to change your peak sports performance time.

The differences in how our bodies react to physical activity are caused by the circadian rhythm—the body’s molecular clock responsible for regulating behaviors such as sleep and appetite throughout the 24-hour day.

A central clock in the brain, located in the hypothalamus, reacts to light exposure through signals from the optic nerve. This circadian pacemaker is known as the suprachiasmatic nucleus. It sends signals to the peripheral clocks of other organs, muscle tissue, and adipose tissue, keeping the entire body in sync.

But these peripheral clocks can be adjusted by other cues, such as when we eat or perform certain activities. This is how the “skeletal muscle clock” reacts to exercise. That’s why we can tune it by regularly exercising at different times. However, just as this procedure can affect performance, it can also alter the effect of exercise on our health.

Circadian Rhythm: The Body’s Internal Clock Influencing Exercise Performance

Physical education professor Juleen Zierath from the Karolinska Institute in Sweden researches the interaction between exercise and the circadian system. She and her colleagues found that mice that exercise in the morning burn more fat. Zierath’s findings indicate that physical activity performed at an optimal time of day can maximize the health benefits for individuals with metabolic diseases such as type 2 diabetes and obesity.

“Everyone agrees that exercise is good regardless of the time of day, but maybe it’s possible to control metabolic outcomes based on when you exercise,” Zierath explains.

Her findings reflect a recent study in humans, which demonstrated that maintaining an exercise regimen for one hour, one day a week, including weight training, high-intensity interval training, stretching, and endurance, can reduce abdominal fat and blood pressure in women. But interestingly, when women perform the same exercises at night, it increases their muscle performance.

For men, exercising in the early evening helps lower blood pressure and stimulates the breakdown of body fat. However, research in this area is still evolving. Recent analyses of previous studies suggest that this evidence on the advantages of the time-of-day effect on exercise performance or health benefits is somewhat inconclusive.

Training at the Right Time: Adapting Your Body for Optimal Results

What is the best time to exercise

One of the reasons, almost certainly, lies in the differences between individuals. The timing of peak sports performance, for example, differs between individuals with morning and evening chronotypes—also known as early birds and night owls.

“There are variations in the timing of our clocks,” explains physiologist Karyn Esser from the University of Florida in Gainesville, United States. According to her, “early birds have a clock that probably runs a little less than 24 hours, and night owls probably have a clock that runs a little more than 24 hours.”

But if you find that your circadian rhythm doesn’t allow you to perform at your best during the times you are available, exercise can help “reset” your muscle clock. A group of researchers led by Esser concluded that systematically training mice with endurance running in the morning can cause the rodents’ bodies to adapt to the new exercise regimen. Physical activity apparently shifts the timing of the molecular clocks in their skeletal muscles and lung tissues.

The team’s most recent study awaits publication in peer-reviewed scientific journals. It concluded that the magnitude of performance adaptation was greater in mice trained in the morning compared to those that exercised in the afternoon. And after six weeks of training, the mice trained in the morning and afternoon achieved the same maximum endurance performance.

The researchers indicate that if similar effects are found in humans, athletes may be able to recalibrate their internal “muscle clocks” with proper training. Preliminary evidence demonstrates that physical activity can alter the circadian rhythm of humans. This can help people adjust to specific work shifts or different time zones.

“The simple notion here is that our muscle clocks are actually paying attention to when we exercise,” explains Esser. The key to the process seems to be routine. Our body adapts best to exercise when it is practiced regularly at the same time of day.

“If you’re a regular citizen or even an elite athlete looking to compete, you should try to train specifically for race day,” advises Zierath. “Schedule your training periods so that they are consistent with the time you will need to compete or deliver your best performance.”

Most researchers certainly indicate that physical activity is beneficial at any time. But if you find a time that works and start adopting it, your body may simply adapt to offer an additional advantage.