‘What’s the best time of day to exercise?’ is a question I’m often asked by clients, friends and family. Spoiler alert: I’m not going to tell you when you should exercise, because that should be your decision based on your schedule and your preference. But I can tell you what the research says about morning, afternoon and evening workouts so you can make an informed decision.
Exercising in the morning
Perhaps the most compelling reason to exercise first thing is that you may be more likely to stick with it. One study comparing morning versus evening exercise found that people who worked out at 9am were less likely to skip their workout than those who exercised at 7pm (Brooker et al., 2019). This is probably because later in the day we have more responsibilities that build up, and more time to talk ourselves out of exercising, whereas first thing there’s less chance of other things getting in the way.
Another great reason to exercise in the morning is that exercise can improve our memory and cognition (Basso et al., 2015; Loprinzi & Kane, 2015). This is thought to be because exercise increases blood flow and the transport of oxygen and glucose to the brain, and reduces levels of stress hormones (Quigley et al., 2020). Improved cognition is going to be hugely beneficial for almost any job that you might be doing for the rest of the day, so if you want to feel more mentally alert at work, maybe consider doing a morning workout.
There’s also some evidence that people are more likely to make healthier food choices after exercising (‘healthy’ was conceptualised as more fruits, vegetables and low-fat foods, and less processed, fried and sugary foods) (Joo et al., 2018). Thus if you exercise first thing this could encourage you to eat in a more ‘healthful’ way throughout the day. Additionally, research has found that exercising in the morning can curb hunger by releasing satiety hormones and reducing hunger hormones (Vatansever-Ozen et al., 2011). This means we may be less likely to overeat after a morning workout, which can support weight management.
Morning exercise may also be beneficial for sleep. One study compared the sleep of people who ran on a treadmill at 65% of their maximum heart rate at 7am, 1pm and 7pm, and found that those in the 7am session fell asleep quicker and had more deep sleep than those in the other groups (Fairbrother et al., 2014). Morning exercise may be particularly helpful for sleep if it’s done outdoors, because the exposure to natural light can help to regulate our circadian rhythms, so we feel awake during the daytime and sleepy when it gets dark (Murray et al., 2017).
Finally, one of the best reasons in my opinion to exercise in the morning is for the psychological benefits. Exercise can improve mood and reduce stress, anxiety and depression (Herring et al., 2017; Brand et al., 2018; Lucibello et al., 2019; Gordon et al., 2018; Stubbs et al., 2017), so by getting it done first thing we can set ourselves up to feel great for the rest of the day. Similarly, if you find exercise difficult or anxiety-provoking, doing it in the morning allows you to feel proud of yourself for the rest of the day, rather than worrying all day about that workout you’ve got hanging over you.
Exercising in the afternoon and evening
Although there are clearly many benefits to exercising in the morning, there are also perks to exercising later in the day. One of these is that it might give you the edge when it comes to sporting performance. Our core body temperature increases naturally throughout the day, and our testosterone levels peak in the late afternoon (yes, even women have small amounts of testosterone) (Hayes et al., 2010). These two factors can have a significant effect on our exercise performance. One study found that participants’ anaerobic capacity, which is the energy system we use when sprinting or lifting heavy weights, was 7% greater, and participants took 20% longer to reach exhaustion when they exercised between 5pm and 8pm, compared to when they exercised between 6:30am and 9:30am (Hill, 2013). Our reaction times, endurance and flexibility are also better later in the day (Knight et al., 2013; Kuusma et al., 2016). So if you’re attempting a personal best, you might want to do it in the afternoon or evening.
You’re also likely to have eaten several meals if you’re exercising later in the day, so your blood sugar and carbohydrate availability will be higher, and this will enable you to exercise at a higher intensity than if you were to exercise first thing in a fasted state (Mata et al., 2019). So perhaps if you’ve got a challenging session planned like a speed workout, try doing it in the afternoon or evening and see whether you can push yourself that bit harder compared to in the morning.
Another benefit of exercising later in the day is that it can re-energise us after work. I’ve got many friends and clients who love a post-work workout because it helps them to de-stress and unwind from the pressures of the day, and enables them to transition from work mode to home mode, something particularly important for those who are still working from home right now.
Some people worry that exercising in the evening could affect their ability to fall asleep, but you don’t need to be too concerned. A review of 23 studies found that evening exercise did not negatively affect sleep, and in fact found that people who exercised in the evening fell asleep faster and spent more time in deep sleep than those who did not exercise. The only caveat was that when people did high-intensity exercise ending within an hour of their bedtime they took longer to fall asleep and had less deep sleep (Stutz et al., 2018). So don’t stress about exercising in the evening, but just be sure to do it a couple of hours before you plan to go to sleep, particularly if it’s vigorous.
I think the best time of day to exercise is the time you’ll stick to. Research shows that people who exercise at the same time every day do more exercise than those who do it sporadically (Schumacher et al., 2019), so the key is to choose a time that works for you and keep it as consistent as possible (although obviously this isn’t always an option if you work irregular shifts or your routine varies each week). Personally, my favourite time to exercise is late morning, because I’m fuelled and caffeinated from my breakfast, and it helps me to feel sharp and in a great mood for the rest of the day. However this isn’t always possible due to my work schedule, so often I have to exercise later in the day. Interestingly, I have noticed that I often run a little quicker and can lift a bit heavier when I do it in the afternoon, so it’s great to learn about the science behind this!
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