Revealed: The Best Time To Work Out for Muscle Growth

If you want to build muscle, when is the best time to work out? Are you going to see faster results if you train in the morning? Or is it better to hit the gym later in the day once your body’s had a chance to warm up?

There are pros and cons to whatever time of day you train. But if you want to gain as much muscle as you can in the shortest time possible, the research out there points to the afternoon and evening as being the best time to work out.

Here’s the story…

Morning vs Evening Workouts: Which is Best for Muscle Growth?

Back in 2009, a team of researchers based at Finland’s University of Jyväskylä ran a very simple experiment [1]

They rounded up a group of men, and got them to train in the morning or evening for a total of ten weeks. 

The morning group trained between 7am and 9am, while the evening group did their workouts between and 5pm and 7pm. Both groups followed exactly the same training program, which involved lifting weights 2-3 times a week.

The size of rectus femoris, a muscle in the front of your thigh, was measured using a magnetic resonance imaging (MRI) scan at week 10 and 20. Muscle strength was also tested at week 0, 10, and 20 at a randomly given time of day between 9:00am and 4.00pm.

While all the men gained size and strength, there was no significant difference between groups. Whether the workout was done in the morning or evening, the end result was still the same.

However, a closer look at the results shows that the average muscle gain in the men who trained in the afternoon was 3.5%. But in the men who trained in the morning, it was only 2.7%.

In other words, while the difference in muscle growth didn’t reach statistical significance, the evening workout group saw their muscles grow faster than the group who trained in the morning.

In fact, the evening workout group increased the size of their thigh muscles, on average, 30% more than their counterparts in the morning group.

A follow-up study, this time lasting six months, shows much the same results [2]. But because the study lasted longer, the difference between the groups ended up being that much bigger.

Men who trained in the morning saw their quads – specifically, their outer thigh – grow by an average of 12%. But the ones who hit the gym later in the day saw their thighs grow 50% more quickly.

In other words, training in the evening led to larger gains in muscle mass compared to the exact same training program done in the morning.

SEE ALSO: Fasted Weight Training: The 6 Questions Everyone’s Asking Google

Evening Workouts: Why You’re Stronger

Most studies show that muscle strength wanes in the morning, then gradually improves until it peaks in the early evening.

In one study, researchers looked at the effect of time of day on muscular performance in a group of untrained men in their early twenties [3].

Each man performed a series of strength tests at 8:00am, 12.00pm, 4.00pm, and 8.00pm, using something called an isokinetic dynamometer.

With these machines, you can push as hard or as little as you like, and the machine will only move within small boundaries of the set speed. If you push harder, the speed doesn’t increase but the resistance does. This allows movement speed to be maintained within a very narrow margin.

The result?

Muscle performance was greatest in the evening, but only during the exercises that involved faster lifting speeds.

Studies of older men show similar results. In one trial, ten older men with an average age of 76 performed a series of strength tests at 8.00am, 12.00pm, 4.00pm, and 8.00pm [4].

Similar to young men, the older guys were weaker in the morning than they were in the evening. Of 36 muscle function tests, performance was least impressive at 8.00am in 26 of the tests.

However, while the peaks and nadirs occurred at the same times, the highs and lows weren’t as pronounced as they were in the young.

In other words, the extent to which performance differs between the morning and evening is not as pronounced in older as it is in younger men

Why was performance greater during the faster, rather than the slower movements?

The activation of fast twitch muscle fibers — which are called into action when force requirements are high — is preferentially enhanced at a higher body temperature, which tends to peak in the early evening

If your workouts involve a lot of strength- or power-based movements, chances are you’ll perform better in the evening than you will in the morning.

The same holds true with other forms of exercise, not just resistance training.

In one study, power output during ten 6-second cycling sprints was higher during the first three sprints when testing was done in the afternoon rather than the morning [5].

In another, various measures of muscle power were roughly eight percent higher during an evening cycling workout (6.00pm) compared to the morning (6.00am) [6].

Chronotypes and Workout Timing

Your chronotype reflects how the circadian system embeds itself into the 24-hour day, with peaks in physiology, cognition and behavior occurring earlier or later in the day.

In other words, you’re a morning person, an evening person, or somewhere in between.

Surveys show that roughly one in four of us are morning people. Another one in four are night owls [8]. The other 50% of the population aren’t morning or evening-oriented, but somewhere in the middle. They’re usually referred to as neither-types.

Night owls tend to wake up and go to bed later, and also have trouble getting to sleep at night. Morning-types, on the other hand, go to bed earlier, wake up earlier and usually have a better night’s sleep.

Your chronotype can also affect the way you respond to exercise.

In one trial, Italian researchers report that morning-types perceived a bout of interval training to be harder in the evening than it was in the morning [9]. Evening-types, on the other hand, felt like they were working harder when they trained in the morning.

In general, research shows that morning-types are less fatigued, perceive less effort during exercise, and tend to perform better during a morning workout than neither- and evening-types [10].

Evening-types also need longer to get going, and don’t reach maximum performance levels as quickly after waking up as morning-types.

Some research also shows much greater variability from person to person in the strength of the growth signals sent to muscles with a morning versus an evening workout.

That is, lifting weights later in the day seems to produce a much more consistent rise in the various growth signals sent to muscle fibers [7]. Training in the morning, on the other hand, leads to a more pronounced increase in some subjects, but also a decrease in others.

To quote the researchers directly:

“We found that early morning may induce significantly higher between-subject variation in some muscle growth- or metabolism-related signaling pathways compared to the same loading later in the day.”

In other words, training in the morning may provide an optimal muscle-building stimulus for some people, but not for others.

We still don’t know if matching your workout time to your chronotype will lead to a faster rate of hypertrophy.

But the research on chronotypes does raise the possibility that if you’re an evening person, you may see better results with evening workouts. Morning people, on the other hand, might make faster gains if they train in the morning.

Your Body Can Adapt to Morning Workouts

Your body can adapt to training at different times of day. Even though you may not feel as strong during a morning workout, for example, your body will become accustomed to it [12, 13].

While you might not adapt to morning workouts to the extent that performance is exactly the same as it would be in the evening, you can certainly reduce the size of the difference.

That is, if you normally perform better in the evening, consistently training in the morning will narrow the gap between your morning and evening workouts.

Caffeine can also be a big help. Research shows that pre-workout caffeine reverses some of the morning decline in strength and power, raising performance to levels you might expect to see later in the day [11].

The Best Time to Work Out

All things considered, the best time of day to work out if you want to maximize your rate of muscle growth is going to be the afternoon or evening.

However, not everyone is the same, and there is a degree of individual variability from person to person. The dip in exercise performance in the morning is more pronounced in some than it is in others, and people vary in their ability to adapt to morning workouts. 

Something else to consider is what you do before a workout.

For example, if you have a physically demanding job, you can end up tired and fatigued by the end of the day. As a result, your performance in the gym will suffer, and you may be better off training before you go to work.

The same can also be said of jobs that require a lot of mental effort, or even if you have a long and stressful commute.

Mental fatigue has been shown to affect exercise performance, and has the potential to offset any benefits of training in the evening.

From a research review on the subject published in the journal Frontiers in Physiology [14]:

“Mental fatigue can be brought about by the sustained performance of a single cognitive task but importantly can also include different tasks that require mental effort, such as fatigue incurred through a working day.

“Mental fatigue has been shown to reduce time to exhaustion during high-intensity cycling, reduce average running speed during a 5-km running time trial and increase the perception of effort during a prolonged submaximal isometric contraction.”

In other words, a stressful day at work, or even just a few mentally demanding tasks, can still hurt your performance in the gym. In many cases, you’re better off training in the morning when you’re physically and mentally fresh.

Why the Best Time of Day to Exercise Depends on You

Ultimately, the best time of day to exercise is the time of day that works for you and fits your schedule.

“There is no reason to split hairs over fluctuations in body temperature, testosterone, and pain tolerance at different times in the day,” says trainer and boxing coach Ross Enamait.

“No one is weak or overweight because they are exercising at the wrong time. The body can adapt to almost anything, and that includes exercising at various times.”

Personally, I’ve trained at virtually every hour of the day.

Back when I was studying at University and working a full-time job at the same time, I would sometimes train in my garage gym at around midnight, simply because that was the only time I could fit it in.

However, I much prefer to get it done and out of the way in the morning.

Even though I feel slightly weaker at this time of day, the benefits of morning exercise (for me, anyway) far outweigh the downsides.

Firstly, the gym is quieter, so I don’t have to wait around to use the equipment. Morning exercise also gives me more energy and brightens my mood for the rest of the day.

I certainly don’t think of myself as a morning person. The fact I prefer to train early in the day doesn’t mean I’m one of those “eager beavers” who wakes up with a smile on his face and a spring in his step, ready and raring to go.

Morning workouts have simply become a habit that has developed over a period of many years.

In the end, hard work and consistency is far more important than matching your circadian rhythms to your workout schedule, or setting records every time you train.

Final Thoughts

All things considered, if you have the luxury of being able to train at whatever time of day was optimal for muscle growth, it would probably be the late afternoon or early evening.

However, chances are you aren’t in that position, and will need to find a training time that works for you.

Ultimately, the best time to workout is the time of day that works for you and fits your schedule. While timing matters, it’s a lot less important than simply making it to the gym in the first place.