Your alarm goes off. Somehow you get dressed, drag yourself to the gym, and start squatting. But why does it feel so difficult? Your legs are heavy and the weight you lifted just two days ago – in the afternoon – seems almost impossible. No, you’re not imagining that. There is a large body of evidence to suggest that most of us are stronger, more powerful, and have better endurance later in the day.
There are several reasons why it is more difficult to exercise early in the morning. Here’s why, and how you can adapt morning exercise if you need to.
Your circadian rhythm affects your exercise
Your body has a natural 24-hour clock that regulates hormones, body temperature, and when you feel awake or ready for sleep.
This clock is called your circadian rhythm. It is controlled by the brain but can also be affected by external factors such as sunlight. This may explain why practice Winter mornings can be especially difficult for some of us. Research shows that your circadian rhythm is clearly linked to exercise performance, which tends to follow a circadian pattern.
Most people peak between 4 and 7 p.m. This means that we tend to be stronger, faster and more powerful in the afternoon and early evening. We don’t know exactly why. But there are some possible explanations.
Body temperature
Your core body temperature is lowest at 5 a.m. and increases steadily throughout the day. When your body temperature rises, your muscles contract more efficiently. We think this is part of the reason why people typically feel stronger and more powerful later in the day.
Hormonal fluctuations
Insulin – the hormone that regulates blood sugar (glucose) levels – tends to be highest in the morning. This results in lower blood sugar, which means less glucose your body can use for fuel, which likely affects how hard you can push.
Most people peak between 4 and 7 p.m. (Source: Freebeck)
Nervous system function
Although we don’t know exactly why, there is some evidence to suggest that your nervous system is better at sending signals to your muscles throughout the day. This allows you to use more of your muscle fibers during exercise, essentially making you stronger.
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But what if you’re a morning person?
Your sleep chronotype can also affect your exercise performance. This describes your natural tendency to sleep and wake up at certain parts of the day – whether you are a “morning person” (“early bird”), or feel more productive and alert in the evening (“night owl”). Research shows that night sleepers with a late chronotype perform significantly worse when exercising in the morning, compared to people with an early chronotype.
While we don’t know why this happens, it’s possible that night owls experience less fluctuations in hormones and temperature throughout the day — although this is just speculation. Interestingly, sleep deprivation appears to affect physical performance more in the afternoon than in the morning. So, if you stay up late and don’t get enough sleep, you may find it easier to exercise the next morning than the next afternoon.
So, does timing matter?
At any time of the day, if you feel like you’re working, you’ll make progress – for example, increased muscle strength, improved aerobic fitness and heart health. So, if you’re exercising to get bigger, stronger and fitter, timing doesn’t actually matter. Furthermore, when we exercise it is often due to stimulation and rest. If you like to exercise early in the day and this works for you, there is no reason to change.
But you can adapt if you need
If you have a sporting event coming up in the morning — and you usually train in the afternoon — you may want to prepare by doing some exercise early so you’re at your peak. There is evidence to suggest that frequent training in the morning can bridge the gap between your afternoon and morning performance. Basically, your body can get used to exercising at a certain time, although it may take a few weeks to adapt.
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Finally, if you find that exercising too close to bedtime makes you feel hyper-alert and disrupts your sleep, you may want to try doing something gentler at night and/or exercising earlier in the day.
(tags for translation) Circadian rhythm
