Is There A "Best" Time Of Day To Exercise?
Everyone has their own theories and preferences about the "right" time
of the day to exercise. Some people, such as 5-time Mr. Universe
Bill Pearl, like to get up early and finish their workouts before
dawn. Others prefer to exercise in the late
afternoon or evening.
Measures of muscular performance (such as strength and power),
as well as hormones (like testosterone, cortisol and growth
hormone) have their own unique rhythm or timing pattern, where
there are low points and high points over the course of a
day.
But how much does it all really matter? Should your workouts be
timed to coincide with a certain hormonal profile, such as a high
testosterone-cortisol ratio? Is the time of day you exercise all
that important?
Performance
As a rule-of-thumb, most people seem to be strongest in the afternoon
or evening. And most of the studies I've seen also show that muscle
strength wanes in the morning and gradually improves until it peaks
in the early evening.
One study, published in Medicine and Science in Sports and
Exercise,
looked at the effect of time of day on muscular performance in
a group of untrained men in their early twenties [1]
Each man performed a series of strength tests at 8:00am, 12.00pm,
4.00pm, and 8.00pm. The results show that muscle performance was
greatest in the evening, but only during the exercises that involved
faster movements.
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 [2].
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.
"Simply stated, in an aged system, the peaks and nadirs occur
at the same times as they do in a younger system," say the researchers, "but
these highs and lows are not as pronounced as those observed among
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?
One theory is that 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
So, if your workouts involve a lot of strength- or power-based
movements, the chances are you'll perform a little better in the
evening than you will in the morning.
Hormones
Hormones such as testosterone (an "anabolic" hormone)
and cortisol (a "catabolic" hormone) also
vary during the day. Testosterone, for example, peaks in the morning
and drops at the end of the day.
However, while resting testosterone levels reach a low point in
the evening, the rise in testosterone after exercise appears to
be greater in the evening than it is in the morning [2].
Resting levels of the hormone cortisol are also higher in the
morning and lower in the evening. But the cortisol response to
exercise is lower in the early evening (7.00pm) compared with
the morning (7.00am) [5].
In
other words, the testosterone-cortisol ratio (when testosterone
levels are highest relative to cortisol levels) is higher in the
early evening than it is in the morning.
This, in theory at least,
makes the evening the least "catabolic" time to train
[4].
Changes in hormones are all well and good, but you probably want to know whether the time of day that you train is going to have an impact on your results in the gym.
Are you going to build more muscle and lose fat faster if you train in the morning or the evening?
Body composition
One study, presented at
the 2005 National Strength and Conditioning Association's annual meeting
in Las Vegas, looked at the effect of training in the morning or
evening on muscle mass, body fat and strength.
A group of 16 men trained for 10 weeks either before
10.00am (AM group) or after 6.00pm (PM group). Workouts consisted
of 45 minutes of weight training followed by 45 minutes of cardiovascular
exercise.
The PM group had a 3.2% increase in lean mass, compared with
a 0.6% gain in the AM group. Body fat dropped by 4% in the PM group,
while it actually increased by nearly 5% in the AM group. However,
none of these changes was sufficient to reach statistical significance.
At first glance, these results support the idea that training in the evening works better than training in the morning.
The problem here is that studies presented at conferences are
often poorly controlled, and there's usually little or no information
available about how the research was done.
This study, for example, was done
at the University of Southern Mississippi. I'm guessing that
the subjects who took part were also students at the university.
Based on my experience of students, a lot of them are still asleep
at ten in the morning. Maybe the AM group didn't make much
progress because most of the subjects skipped the workouts and
stayed in bed. Perhaps they were all so tired that they just
went thought the motions before sinking their face into a plate
of pancakes for breakfast.
Lead researcher Tim Scheett refers to the effects that he observed as ‘small’, and did not regard them as big enough to discourage people from training in the morning.
“You should train at a time that is most convenient to you and at a time which feels comfortable", stresses Scheett.
A similar study, this time from researchers based in Finland's University of Jyväskylä, also shows slightly greater gains in muscle size when training was performed in the evening [8].
For the first 10 weeks of the study, subjects (a group of young men) trained between 5:00pm and 7.00pm.
The men were then assigned to a morning or afternoon training group. The morning group trained between 7:00am and 9:00am, while the afternoon group did their workouts between and 5:00pm and 7.00pm. Both groups followed the same training routine.
The size of quadriceps femoris, a muscle in the front of the 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 4.00om
Although all the men gained size and strength, there was no significant difference between groups.
However, a closer look at the results reveals 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%.
Statistically speaking, this wasn't a big enough difference to register as a "significant" result. Maybe if the groups had been bigger, or if the training program had lasted for a longer period of time, we would have seen more of a difference.
Does this mean that training in the morning means that you'll make slower progress?
Not exactly.
For the first 10 weeks of the study, the men trained in the afternoon. If you've ever tried moving from an evening workout to a morning one, you'll know that it can sometimes take a few weeks before your body gets used to the change in routine.
If all the men had started out by training in the morning, which would have given them 10 weeks to get used to it, we might have seen a very different set of results.
Chronotype
Something else that you'll need to take into account
when deciding on the "best" time of day to train is your chronotype.
According to some studies, "owls" (evening chronotypes) are more alert during
the evening, while "larks" (morning chronotypes) are more "alert" in
the morning [6, 7].
If you're an Owl, you could see better results
by training in the evening, while Larks might make faster progress
if they train in the morning.
Personally, I've trained at virtually every hour of the day, though
I much prefer to get it done in the morning. Even
though I know I'm 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.
However, when I was studying at University (and working a full-time
job at the same time) I would often train around midnight, simply
because that was the only time I could fit it in.
The only time of day I actively avoid exercise is in the
early afternoon, where I tend to suffer from a post-lunch "dip" in
energy. Some studies also show that certain aspects of performance
deteriorate at this time even if no food is eaten at lunchtime [3].
If you want to get in shape and stay that way, exercise will need
to be something you do most days of the week for the rest of your
life. And there'll be times when you won't be able to match your
circadian rhythms to your workout schedule, or set records every
time you train.
Don't be discouraged. It's a lot more important
to work hard and be consistent
than to waste time and energy second-guessing whether you're training at
the "right" or "wrong" time of day.
About The Author
 Christian Finn holds a master's degree in exercise science, is a certified personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Muscle & Fitness, Fit Pro, Zest and other popular fitness magazines.
If you're stuck
in a rut with your current exercise and diet plan... fed up with
only losing a pound here and there... or still skinny after months
(or even years) of trying to build muscle and gain weight... click here now for instant access to his step-by-step muscle-building and fat-burning workout routines.
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References
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K.M., & Ramsey, K. (1998). Biorhythmic influences on functional capacity
of human muscle and physiological responses. Medicine
and Science in Sports and Exercise, 30, 1399-1407
2.
Deschenes, M.R., Bronson, L.L., Cadorette, M.P., Powers, J.E., & Weinlein,
J.C. (2002). Aged men display blunted biorhythmic variation of muscle performance
and physiological responses. Journal
of Applied Physiology, 92, 2319-2325
3. Atkinson, G., & Reilly, T. (1996).
Circadian variation in sports performance. Sports
Medicine, 21, 292-312
4. Bird, S.P., & Tarpenning, K.M.
(2004). Influence of circadian time structure on acute hormonal responses
to a single bout of heavy-resistance exercise in weight-trained men. Chronobiology
International, 21, 131-146
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Kanaley, J.A., Weltman, J.Y.,
Pieper, K.S., Weltman, A., & Hartman, M.L. (2001). Cortisol and growth
hormone responses to exercise at different times of day. Journal
of Clinical Endocrinology and Metabolism, 86, 2881-2889
6. Bailey, S.L., & Heitkemper, M.M. (2001). Circadian rhythmicity
of cortisol and body temperature: morningness-eveningness effects. Chronobiology
International, 18, 249-261
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Merrow, M., Spoelstra, K., & Roenneberg,
T. (2005). The circadian cycle: daily rhythms from behaviour to genes. EMBO
Reports, 6, 930-935
8. Sedliak, M., Finni, T., Cheng, S., Lind, M., & Häkkinen, K. (2009). Effect of time-of-day-specific strength training on muscular hypertrophy in men. Journal of Strength and Conditioning Research, 23, 2451-2457
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