Are you working out at the wrong time of day?

Should you force yourself out of bed and hit the gym first thing? Or are you better off pressing snooze and scheduling an evening workout instead? It’s not just down to preference. A string of new studies suggests that when it comes to effective exercise, it isn’t what you do, but when you do it that counts.

“We now know that our internal physiology changes over the course of a day, as levels of chemicals, hormones and proteins ebb and flow,” says the sleep scientist Dr Michael Breus, author of The Power of When. “Research indicates that an individual’s athletic performance can vary by as much as 26 per cent depending on the time of day they work out.” The optimum hours for an individual to exercise will depend on “chronotype” — whether you’re a morning lark or a night owl — gender and fitness goals.

While morning gym sessions used to be the norm, the rise in working from home and changing schedules have allowed for more flexibility. According to data from the booking app ClassPass, 5.30pm on Wednesdays was the most popular time to work out in 2023.

Could you be getting more out of your workouts if you exercised at a different time of day?

The bright and early club

A 2023 study published in the European Journal of Preventative Cardiology found that, for those of us wanting to fend off heart disease and strokes, the optimal time of day to move is between 8am and 11am. “Women appeared to benefit the most, reflecting earlier studies from the US that found women who exercised in the morning shed more abdominal fat than women who exercised later in the day,” Breus says. And the female morning movers were also more likely to lower their blood pressure.

Insomniacs among us should exercise in the morning. The personal trainer Shona Vertue points to a 2014 study that found people who walked on a treadmill at 7am experienced the largest drop in blood pressure, and the most time spent in deep sleep later that night. “Anecdotally I’ve definitely found that morning training makes you sleep earlier and better,” she says.

But don’t try to jump out of bed at 5am and expect to run a PB. Personal trainer Nick Finney advises his clients to wait at least an hour after waking to exercise, and to eat and drink, even if it’s just water and a banana. “First thing in the morning you’re dehydrated and need fuel inside you to perform,” Finney says. “Your core body temperature is also lower on first waking up, so you’re more vulnerable to injury. Most people will have a more efficient workout after at least one meal, and doing a warm-up is even more important if you’re exercising soon after waking up to prevent injury.”

Psychologically, a morning workout sets you up for a good day. “There’s evidence that a morning workout is more likely to become ingrained as a habit, and it might help you make healthier choices throughout the day,” Finney says.

The night train

Multiple studies suggest that afternoons and evenings are the best time to lift weights. Our muscles increase in strength during the day, so by late afternoon they are at their peak, enabling us to lift more, for longer. Researchers have found that evening exercisers improved their upper body strength by 7 per cent more than the morning group, and they also powered through more sit-ups and push-ups. “Studies have also concluded that evening weight training makes muscles larger, particularly in men,” Vertue says.

The same goes for yogis — body temperature is highest around 6pm, meaning you’ll be at your most flexible at this time. Endurance is also better after work. People who exercise in the evening take up to 20 per cent longer to reach the point of exhaustion. It’s probably no coincidence that most Olympic and world records are won in the late afternoon.

If you’re a man who wants to exercise for health reasons, you’re better off working out in the evening. Research from Skidmore College in the US found that men who exercised later in the day markedly reduced their blood pressure, cholesterol, body fat and feelings of fatigue. People at risk of diabetes improved their blood-sugar control more if they worked out in the evening rather than the morning.

“There’s an argument to be made for exercising after work because it delivers a surge of endorphins that suppress appetite — right as you enter the time when many people are prone to overeating,” Finney says.

But try not to train too late into the night. Studies have shown that physical exertion up to an hour before bedtime can cause insomnia, and that exercising between the hours of midnight and 6am is associated with a greater risk of heart disease and stroke.

The midday movers

What about people who sneak off to an exercise class in their lunch break? They may outlive us all. “Studies have shown that people who clustered their physical activity between 11am and 5pm or spread it out throughout the entire day were less likely to die prematurely from heart disease or other causes than those who exercised outside these times,” Buell says. “This is especially pronounced in men and the elderly, one reason being that this afternoon time-frame neatly coincides with the time of day when, statistically, people are least likely to experience a heart attack.”

Researchers at San José State University in California also showed that reaction times and hand-eye co-ordination, especially in sports such as tennis and football, improved after midday. “Another bonus is a burst of exercise after lunch can fend off the afternoon slump,” Vertue adds.

The time is now

All the experts agree that working out at any time is better than not working out at all. Vertue advises her clients to try and change the time of their workout and then pay attention to their recovery, performance and how they feel. “Collecting your own data on these things is imperative because research can’t answer for every individual,” she says.

For Finney, consistency is key to progress. “American studies have shown there are benefits from working out at the same time each day,” he says. “Weightlifters who trained at the same time of day consistently gained more power than those who worked out at different times. So once you’ve found the ideal time for you, stick to it.”