Some people swear by a morning run; others prefer to head to the gym after work. Exercising first thing means getting it done before the day’s demands take over, while an evening session can offer a chance to unwind.
There is no denying that exercise is good for us, whenever we do it. Yet a recent Asics report, The Movement Conservation Report, highlights just how sedentary modern life has become. It found that people spend 86 per cent of their waking hours not moving, while almost two-thirds of adults say it is now easy to go an entire day barely moving at all.
As the mornings grow darker and colder, dragging yourself out of bed for a workout can feel like a tall order. But does exercising first thing offer any particular advantages? From waking up your brain to improving consistency, here is what happens when you get moving in the morning.
Waking up your brain
For those working nine-to-five – or simply keen to get ahead of the day – a 6am start is nothing unusual, even if it feels closer to midnight in the depths of autumn and winter.
That groggy feeling when the alarm goes off is partly down to sleep inertia, the temporary dip in alertness as the brain adjusts to being awake. Attention, reaction times and decision-making can all take time to return to their usual levels, particularly after insufficient sleep.
Fortunately, the body has its own way of preparing for the day. Cortisol levels typically rise in the minutes after waking, in what is known as the cortisol awakening response. Meanwhile, “body temperature, heart rate and blood pressure adjust as we move from sleep to wakefulness,” explains David Raichlen, professor of anthropology and biological sciences at the University of Southern California and co-author of the new report.
Before launching into a demanding workout, give yourself a few minutes to warm up. Gradually increasing your heart rate and breathing allows your body to adjust to the demands of exercise, rather than going from bed to full throttle.
Getting your heart pumping
As you begin exercising, your cardiovascular and respiratory systems respond rapidly. Working muscles need more oxygen to produce energy, so your heart beats faster and pumps more blood around the body. Adrenaline and noradrenaline help drive this response, while your breathing becomes faster and deeper to deliver oxygen and remove carbon dioxide.
The harder you exercise, the greater these demands become. But you do not need to run at full pelt to get your body working: even a brisk walk increases energy expenditure and makes your heart and lungs work harder than they would at rest.
Improving your sleep
“Morning movement may also help reinforce your body’s internal clock, particularly when combined with daylight,” Prof Raichlen says. “Over time, this helps reinforce the distinction between daytime activity and nighttime rest.”
Research suggests that exercise timing can influence circadian rhythms, although the effects vary between individuals. A review of the evidence examined the relationship between exercise, circadian rhythms and sleep. It found that morning exercise can advance the timing of dim-light melatonin onset (DLMO) – the point at which the body begins producing melatonin in the evening – potentially improving sleep quality and helping people whose natural sleep-wake cycle runs later.
However, this does not mean an early workout will automatically improve your sleep. The effects depend on factors including your existing body clock, the timing and intensity of exercise, and exposure to light. “Nor should you sacrifice sleep to fit in a workout: getting enough rest remains essential for recovery and overall health,” Prof Raichlen adds.
Burning more fat
Some people find it easier to exercise before breakfast; others do it because they have heard that working out on an empty stomach burns more fat. There is some science behind this idea. After an overnight fast, insulin levels are generally lower and the liver’s glycogen stores – its readily available carbohydrate reserves – have fallen. During exercise, the body may therefore rely more heavily on fat for fuel, particularly during lower-intensity activity.
This effect can persist after the workout, explains Dr Adora Yau, a nutritional and exercise physiologist at Manchester Metropolitan University. A study published in eBioMedicine investigated how exercising before or after meals affected fat oxidation (the metabolic process of breaking down fat into usable energy) over 24 hours. It found that a 60-minute workout before breakfast increased fat oxidation compared with remaining sedentary, while exercising after lunch or dinner did not produce the same effect.
“Exercise in the fasted state may lead to additional health benefits like a reduction in insulin responses to food ingestion [greater insulin sensitivity] and a decreased risk of type 2 diabetes and cardiovascular disease, plus greater adaptive responses to exercise even when energy balance is unaffected,” Dr Yau adds.
However, burning more fat for fuel is not necessarily the same as losing more body fat over time, Prof Raichlen says. The body adjusts its use of fat and carbohydrate throughout the day, so a greater reliance on fat during one workout does not always translate into greater long-term fat loss.
If you enjoy exercising before breakfast and feel comfortable doing so, there is no need to eat simply because you are about to do a short, easy workout. For longer or more intense sessions, however, eating beforehand may help you perform better. If you are training regularly, “getting enough energy to support your activity is more important than trying to maximise fat-burning during an individual workout”, Prof Raichlen says.
Boosting your mood and concentration
By the time you have showered and are getting ready for work, the effects of your workout may extend beyond your muscles, metabolism and cardiovascular system. Exercise “has acute effects on alertness, mood and cognitive function” that can continue after a workout, says Prof Raichlen. Exercising before work can mean you feel more alert as the day begins. It may also be easier to stick to a routine when exercise is done before other commitments take over.
Dr Yau agrees. “You get it out the way, it’s done and you feel good and energised,” she says. “Whereas, in the evening, it is easy to come up with excuses after a day of work and you may end up not doing anything.”
It’s important to remember that “you don’t need to do anything intense first thing,” Prof Raichlen says. “A brisk walk, an easy run or a few minutes of mobility are all good options. If you can get outside once it’s light, even better, as you’re pairing movement with daylight. And try not to treat that morning session as your entire movement allowance for the day.”
Ultimately, morning exercise can help establish a routine, combine movement with daylight and leave you feeling more alert for the day ahead. If getting up early works for you, there are plenty of reasons to keep at it. If it does not, you can still reap the benefits later in the day. “The best workout is one you can fit into your life consistently – without sacrificing the sleep, food and recovery your body needs,” Prof Raichlen concludes.