What's the Best Time of Day to Work Out?

Published March 21, 2022 10:59AM

Are you an up-with-the-sun, “early bird gets the worm” kind of athlete? Or do you prefer an evening workout to unwind from the stress of the day?

Whether you’re an early riser or a night owl, one thing everyone can agree on is that the most important thing isn’t when you work out, but that you get it done. Yet while you’re getting that work done, consider that certain types of workouts might be better suited for different times of the day.

Working Out in the Morning

By checking off the training box first thing in the morning, you avoid unexpected distractions that might crop up throughout the day and derail your plans of fitting in your session after work. Sticking to a consistent workout plan ultimately leads to better/faster fitness gains. For that reason alone, doing a morning workout might help your fitness goals. In addition to giving your metabolism a jump-start, morning exercise also provides a feel-good endorphin boost and a sense of accomplishment, which can lead to more productivity throughout the day.

Tim Snow, a coach with QT2 Systems, prefers scheduling swim workouts in the morning. “I’ve always believed that swimming, being the gentlest of all three disciplines on the body, made it something I could handle early in the morning,” he said. “Whereas if I run too early, I’m just not the same the rest of the day. A lot of it depends on the intensity of what you’re doing.”

Having said that, Snow often sees athletes combine swim and gym sessions into a single morning workout. “This may have more to do with convenience; because, in many cases, the pool and gym connect, so you can knock them out at the same time.”

If you need to double up on workouts, it’s best to group a key workout (like an interval swim) with a lower intensity session (like a gym workout). Don’t double up on two key sessions – it’s important to separate those. “For example, if I have an athlete do a key bike and a key run session, that need to be separate from one another, I will schedule the key bike in the morning, and the run is intended to be later in the afternoon or evening. These are triathletes who have jobs and families, and, as a result, workouts often have to be done both before and after work.”

Those hard workouts could also be good stress relief—yes, more so before work. Research has shown that a session of hard intensity exercise before work might blunt the body’s stress response later in the day.

If we’re being gender-specific, women who work out in the morning tend to get about 20 minutes more physical activity than those who work out at night, according to one study.

Research has also shown that exercising earlier in the day (as opposed to later in the afternoon or evening) not only increased total sleep time, but also decreased sleep-onset latency, or the time it takes you to fall asleep. Specifically, aerobic exercise was associated with an increase in the deeper more restorative stages of sleep. One study had individuals perform 30 minutes of aerobic exercise on a treadmill at 7 a.m. and at 1 p.m. The time spent in deep sleep was significantly altered by the timing of exercise—63 minutes for the 7 a.m. workout versus 43 minutes for the 1 p.m. workout.

When it comes to downsides of morning workouts – besides being unable to hit the snooze button, that is – the early morning hours are when your core body temperature is at its lowest, so a more extensive warm-up might be needed. Also, the decision of whether to work out in a fasted state or eat breakfast first is always a challenge for those who easily suffer from GI distress.

Working Out in the Evening

If you regularly have to do your workouts at night, you’ve probably worried about how revving up your heart rate affects your sleep. But at least one study found that runners who performed high-intensity exercise in the evening slept better in a controlled lab setting than those who didn’t—turning traditional thinking on its head. However, because hormones like adrenaline are secreted during intense training, Sebastien Racinais, PhD, still advises athletes to avoid working out too late.

One of the other factors that may be affecting your sleep with later workouts, though, is the timing of food, which can be tough to get right during the day. “Try not to overload the stomach with a gargantuan meal too close to the start of the exercise,” Racinais said. “A time of three hours is generally allowed.”

RELATED: Why Do I Have Trouble Sleeping After A Hard Workout?

The upside of workouts in the evening is that research has shown that workouts relying on muscle force and power, like hill repeats on the bike, might be better when done later in the day. Research by Racinais showed that body temperature is highest between 2-6 p.m. This temperature increase is believed to have a passive warm-up effect on the muscles, improving their ability to contract, which means that muscle force and short duration performance are often better in the afternoon. This might make it the perfect time for an interval run or squats in the gym.

“Variations in body temperature have been well-known to physicians for a long time. On the other hand, it’s only more recent that we realized that muscle power also varies according to the time of day,” Racinais said. “These variations are actually due to variations in body temperature, approaching its maximum around 6 p.m. It has an effect similar to that of your warm-up and helps to improve muscle performance. This explains why your performance during sprint exercise peaks around 6 p.m. However, this peak can be shifted by shifting your sleep and meal times.”

Want further evidence that you should do that FTP test or those track intervals in the afternoon? Another study by Racinais had eight men do max cycling sprints in the morning (7-9 a.m.) and afternoon (5-7 p.m.); body temperature, maximal force, and muscular power were all higher in the afternoon. Other studies have similarly reported improved performance in the afternoon for outdoor sprint running velocity and time to exhaustion has been shown to be 20% greater during high intensity cycling tests that take place in the evening.

Train When You’re Going to Race

That’s all great, except most races don’t take place from 5-7 p.m. While the science might help you better plan your daily workouts, you can’t choose your race start times and triathlons typically start in the morning. Therefore, is it better to get those key workout done in the morning, simply because that’s when you will be racing?

“A study carried out by a Japanese laboratory observed that if one trained three groups of subjects—with one in the morning, one in the afternoon, and one in the evening—only those trained in the afternoon increased their VO2 max when it was measured during the afternoon,” Racinais said. “But make no mistake, it shouldn’t be concluded that training in the afternoon makes you progress more, but rather that one progresses mainly at the time when one trains. It has been observed that subjects trained in the morning had a higher threshold in the morning, whereas subjects trained in the afternoon had higher threshold in the afternoon.”

“What should be remembered from this research is that there is an interaction between the time of our training and the time when our body is most efficient. Greater progression indeed seems to occur at the time of day when training is regularly performed. If you know what time your goal for the season will be, you know what you have to do…”

What's the Best Time of Day to Work Out?

Working Out in the Morning

Working Out in the Evening

Train When You’re Going to Race

Tips For Working Out Any Time of Day