The Best Time To Exercise, According to Science

Download Our FREE
Spartan Race Training Plan
Our comprehensive training plan provides you with 30-days of exercises right up to race day!
Download e-Book

The optimal time of day to train is not something that people often think about. Usually, the idea is whenever you can fit a workout in is the best time. Better to do a workout at 6 am then not all, right? Well, that might not be the case. The time you exercise may actually have larger effects than you think. In fact, honing your workout times could lead to better results. 

As it turns out there is a science to optimizing your training times. This science of optimal exercise timing has a lot to do with your body’s natural rhythm. The one rhythm that you really want to pay attention to is your circadian rhythm.  By carefully planning your training schedule in accordance with your circadian rhythm, you can get in a more powerful workout. 

What Is Your Circadian Rhythm? 

Circadian rhythms are found in most living things. This includes animals, plants, and even many tiny microbes. Our circadian rhythm essentially governs our body’s sleep/wake phases. This is also known as a biorhythm. A biorhythm is simply any type of predictable cycle in a living organism. Within this rhythm are physical, mental and behavioral changes that roughly follow a daily pattern.

The circadian rhythm is often referred to as our “body clock” because it is the body’s innate timing device. This natural internal clock works off of environmental cues. The largest environmental cue being your exposure to light.

Our circadian rhythm is managed by a part of the brain called the Suprachiasmatic Nucleus (SCN). Light travels to the SCN from the eye signaling that it is time to be awake. The SCN then triggers other parts of the brain that control hormones, body temperature and other functions that play a role in making us feel sleepy or awake.

The influence of your circadian rhythm is quite large. Influencing your daily patterns of alertness, mood and bodily functions such as digestion. Your circadian rhythm also affects your hormones such as the release of melatonin and cortisol. 

Thus, your circadian rhythm is incredibly important as it dictates many components in your body. This translates into that optimal exercise timing can be achieved by utilizing the best moments in your circadian rhythms to exercise. 

Your Circadian Rhythm & Optimal Exercise Timing

The time window of performing physical activity is broad and can change according to individual differences. In particular, people are in two broad groups. The first being early birds, people who go to bed early and rise early. The second being night owls, people who go to bed late and rise late. This time preference affects all biological rhythms, including the ability to exercise and perform.

When it comes to optimal exercise timing many factors come into play. Below we consider the various research done on all time of the day: the morning, the afternoon, and the evening. 

Exercising In The Morning

In terms of performing a consistent exercise habit, it’s tempting to think morning exercise is more sustainable as it’s “out of the way” before other time pressures may interfere. But there isn’t much evidence to support this theory.

Instead, it may just come down to what your preferred time to train is. As suggested before, if you are a night owl don’t pressure yourself too heavily to waking up at the crack of dawn. The key to optimal exercise timing is to workout when you feel most awake. With the idea being that the more awake you are the more efficiently and powerfully you can train.

Many people like exercising in the morning because they can train on an empty stomach. Exercising on an empty stomach is different, physiologically, from exercising after a meal. After an overnight fast, our bodies are reliant on fat as its primary fuel source, so if you exercise in the morning, before eating breakfast, you will essentially burn more fat.

The 6 Most Effective Fitness and Nutrition Apps

Burning more fat during exercise may have a metabolic advantage, but does that make a difference to fat loss over a period of time? Unfortunately, it’s unlikely. Research examined the difference between exercising in a fasted state, compared with after food, for four weeks. While both groups lost fat mass, there was no difference in the amount of fat lost between fasting or eating before exercise.

Researchers investigating the impact of six weeks of morning versus evening exercise on energy intake and weight loss found those who exercised in the morning ate less throughout the day, and subsequently, lost 1kg more than those in the evening group.

Exercising In The Afternoon

Hitting the gym directly after work isn’t everyone’s favorite thing to do. However, there have been multiple conclusive studies that suggest an afternoon workout could be the best for you. 

One study has determined that the best athletic performance is achieved late afternoon/early evening. This is due to the several exercise-related rhythms that reach their circadian peak. The ability to perform endurance exercise is stable across the day. However during the evening, reaction time, joint flexibility, muscle strength and power reach their highest level. This means exercising at this time has the best results. Including increasing fitness by increasing muscle and reducing fat tissue. 

Also, another study concluded that during afternoon hours the rating of perceived exertion is lower. In regular terms, a “rating of perceived exertion” is a measure that represents how hard a person feels their body is working. This means we feel less exerted so we can work harder and get better results.

One research study found that more fitness benefits could be reaped during the afternoon. From a circadian point of view, it makes sense to see higher benefits from afternoon exercise. Circadian rhythms control your body temperature, which has an impact on your workout.

Your body temperature tends to be a degree or two warmer in the afternoon than in the morning, resulting in better muscle performance and decreased risk of injury. Plus, if you tend to hit that “wall” around 1 p.m. or 2 p.m., going to the gym might be a good way to get past it.

Exercising In The Evening / Before Bed

Despite previous recommendations that discouraged exercising within four hours of bedtime, there’s a growing body of evidence to support evening exercise. Swiss researchers found vigorous exercise performed one-and-a-half hours before bedtime was associated with falling asleep faster, fewer awakenings after sleep onset, and better mood states.

A study published in 2011 found that when people exercised vigorously for 35 minutes right before bed they slept just as well as on nights when they didn’t exercise.

While a study done by the National Sleep Foundation  found quite concrete results. In that study, 83% of people said they slept better when they exercised than when they did not. More than half of those who exercised moderately/vigorously said they slept better on workout days.

Meanwhile, just 3% of late-day exercisers said their sleep quality was worse when they exercised than when they did not. The National Sleep Foundation concluded that exercise is good for sleep, regardless of the time of day it’s performed.

So What Is The Best Time To Exercise? 

study investigating the relationship between circadian preference and sport found athletes tend to select sports with training times that suit their individual preference. So “morning people” were more likely to select exercise like cycling or running, which usually takes place earlier in the day.

If you’re not sure which time of day you prefer to exercise, you can do some experimentation of your own. Perhaps try a month of exercising in the morning, followed by a month of exercising in the afternoon. However, with the increasing realizations of the importance of circadian rhythms, afternoon exercise may be best for optimization. 

Although ultimately, you should listen to your body and let it be your guide in choosing what time of day works best for you. For many people, the “best” time to exercise may also change day-to-day to accommodate schedules, and that’s fine too.

Download Our FREE
Spartan Race Training Plan
Our comprehensive training plan provides you with 30-days of exercises right up to race day!
Download e-Book

Lesley George

Lesley is a content writer and community manager at Shape.
Download Our FREE
Spartan Race Training Plan
Our comprehensive training plan provides you with 30-days of exercises right up to race day!
Download e-Book