For most of us, the "best" time of day to work out is simple: When we can.
That's why we call it a "routine." And if the results are the same, it's hard to imagine changing it up.
But what if the results aren't the same?
They may not be, according to a new study from a research team at Skidmore College. The results of a 12-week exercise program were different for morning vs. evening workouts.
Women who worked out in the morning lost more fat, while those who trained in the evening gained upper-body strength and power. As for men, the performance improvements were similar no matter when they exercised. But those who did so in the evening had a significant drop in blood pressure, among other benefits. The study is part of a growing body of research showing different results for different times of day among different populations. As it turns out, when you exercise can ultimately have a big effect. And we're not just talking strength and fat loss, but also heart health, mood, and quality of sleep.
An Accidental Discovery
The original goal of the Skidmore study was to test a unique fitness program with a group of healthy, fit, and extremely active adults in early middle age.
The program includes four workouts a week, each with a different focus: strength, steady-pace endurance, high-intensity intervals, and flexibility (traditional stretching combined with yoga and Pilates exercises).
But because the group was so large – 27 women and 20 men completed the 3-month program – they had to split them into morning and evening workout groups.
It wasn't until researchers looked at the results that they saw the differences between morning and evening exercise.
The women who worked out in the morning got much bigger reductions in body fat and body-fat percentage than the evening group. Meanwhile, women in the evening group got much bigger gains in upper-body strength, power, and muscular endurance than their morning counterparts.
Among the men, the evening group had significantly larger improvements in blood pressure, cholesterol levels, and the percentage of fat they burned for energy, along with a bigger drop in feelings of fatigue.
Some of these findings are consistent with previous research. For example, a study published in 2021 showed that the ability to exert high effort and express strength and power peaks in the late afternoon, about the same time that your core body temperature is at its highest point.
On the other hand, you'll probably perform better in the morning when the activity requires a lot of skill and coordination or depends on strategic decision-making.
A 2020 study showed that men who exercised between 3 and 6 p.m. saw dramatic improvements in blood sugar management and insulin sensitivity, compared to a group that worked out between 8 and 10 a.m.
They also lost more fat during the 12-week program, even though they were doing the exact same workouts.
Train Consistently, Sleep Well
When you exercise can affect your sleep quality in many ways. Exercise helps you fall asleep faster and sleep deeper at night. The only exception is if you exercise so intensely or so close to bedtime that your heart rate is still elevated.
Exercising at a consistent time every day helps regulate the body's circadian rhythms.It doesn't matter if the exercise is in the morning, evening, or anywhere in between. As long as it's predictable, it will help you fall asleep and wake up at the same times.
Outdoor exercise is even better. The sun is the most powerful regulator of the circadian clock and works in tandem with physical activity.
Third, exercising at specific times can help you overcome jet lag or adjust to an earlier or later shift at work.
Exercising at 7 a.m. or between 1 and 4 p.m. helps your circadian clock to 'fall back' in time, making it easier to wake up earlier
If you need to train your body to wake up later in the morning, try working out between 7 and 10 p.m.
All Exercise Is Good, but the Right Timing Can Make It Even Better. If you're more focused on building upper-body strength and power, you'll probably get better results from training in the afternoon or evening.