If you love sleeping in on weekends, find out how to schedule your workouts so you’re not dragging on Monday morning.
What’s the best time of day to work out? The conventional wisdom—which still holds true—is that you should choose a time when you’ll actually do it.
But if you have more freedom in your choice, you may want to pick a time that’s best for your body clock, a new study suggests.
Researchers at Arizona State University recruited about 100 people to examine whether exercising at different times affects circadian rhythm, or your body’s sleep-wake cycle, enough to be beneficial the next day. The participant pool included both men and women, ranging in age from 18 to 75. All were considered aerobically fit.
They found that exercise at 7 a.m. or between 1 p.m. and 4 p.m. advanced the body clock enough that people were able to start activities earlier the next day. That means they felt more refreshed and ready to work out sooner after waking up. By contrast, exercising in the evening between 7 p.m. and 10 p.m. delayed the body clock, which means they had a harder time getting to peak-performance mode until later the next day. So, they felt more sluggish and snooze-prone when first waking, but did have energy later.
These findings may be particularly important for those who have interruptions to their circadian rhythm, such as first responders, third shift workers, and travelers with jet lag, according to the study’s co-author, Shawn Youngstedt, Ph.D., a professor in the ASU College of Nursing and Health Innovation.
He told Runner’s World that this also includes those with “social jet lag,” which means sleeping late on the weekends after staying out late the night before, a habit that can throw off your body clock. If you love the weekend sleep-in, but have a problem dragging yourself out of bed on Monday to get your morning workout in, you can schedule Sunday’s sweat session between that advantageous afternoon block of 1 p.m. and 4 p.m. to help set your body’s clock a little earlier for the next day.
Why does exercise have an effect on circadian rhythm at all? Researchers don’t know exactly, Youngstedt said.
But, he added, there is some evidence that two compounds in your body—the hormone and neurotransmitter serotonin and neuropeptide Y—may play a part. Exercising tends to regulate their release, helping your body clock function properly.
That morning or early afternoon time slot can be helpful for getting back on a track, but knowing about evening exercise could also be handy for those trying to adjust to night work, Youngstedt added. For example, a nurse who starts to do overnights may want to shift to evening exercise as a way to reset the body clock for that delayed peak performance timeframe.