With a heatwave sweeping across the UK, plenty of us are trying to work out how to keep training without keeling over.
And while there are obvious mood-boosting benefits to exercising in the sunshine, heat changes the game. Push too hard, or ignore the early warning signs from your body, and performance can plummet – something research has consistently shown when exercise is performed in hot conditions.
'Performance will always suffer proportionally to an increase in temperature,' says strongman and doctor Emil Hodzovic.
It's clear we should approach heatwaves with caution. So, follow these tips to keep heatstroke and heat exhaustion on ice.
Can You Exercise in a Heatwave?
Yes – but the key is to train smart. Here are our top tips for exercise in the heat.
1. Stay Hydrated
'Hydrate above and beyond what you expect you’ll need,' says Hodzovic. 'Sweat needs to be replaced and you’ll lose litres an hour, far more than you can absorb by drinking.'
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He recommends you continue drinking water even after you’ve finished your session, and switch to an electrolyte drink if it’s been a heavy or long session.
2. Know When to Stop
'It’s not wise to start anything new or out of the ordinary when there’s a heatwave,' says Dr Joseph Lightfoot, founder of Results Inc.
Training that you’re not used to means your body puts out warning signs you might not recognise.
'If you experience lightheadedness, hot or red skin, blurry vision, extreme fatigue, weakness, an excessive heart rate or vomiting, then rest in the shade and rehydrate,' says Hodzovic.
If symptoms persist, consult a medical professional. This is not the time for #nopainnogain.
3. Beware of Humidity
When there’s more water in the air, less evaporates from your skin, which impacts your natural cooling systems.
'In humid heat, sweat becomes less effective,' says Hodzovic. 'So sessions should be adjusted accordingly.'
He recommends taking ice packs to your sessions to drop your body temperature quickly to avoid heat exhaustion. And definitely steer clear of five-a-side in the midday sun.
'Competitive sport isn’t ideal as you’re inclined to push yourself harder,' he adds.
4. Front-Load Your Day
When you’re planning on exercising outside, always try to workout in the morning during a heatwave. Aside from securing bragging rights on Instagram, the temperature is always far cooler at dawn than sunset, since humidity rises towards the end of the day. Whatever you do, try to avoid working out between 10am and 3pm, or you risk more than just DOMS.
5. Dress for the Occasion
Ditch the cotton t-shirt – and by extension, potential sweat patches – and opt for kit that’s designed to handle the heat. Breathable, lightweight and sweat-wicking are the buzzwords you’re looking for, so you can focus on the task at hand without risking chafe and heat rash. Don’t leave the house without a decent pair of sports sunnies to deflect the rays.
6. Scale Back the Session
A heatwave isn't the time to chase PBs or prove a point. Keep the habit, but lower the intensity: reduce your workout volume and take longer rests between sets. You'll still get the benefit of moving, without pushing your body into unnecessary stress when it's already working harder to stay cool.
Are There Any Benefits to Exercising in the Sun?
There are upsides to getting outside in warmer weather, but you don't need to train at peak heat to get them. Daylight exposure can support mood, sleep and vitamin D levels, while outdoor exercise can make training feel more enjoyable. The trick is getting the benefits of sunlight without overdoing it.
Vitamin D
According to the British government’s scientific advisory committee on nutrition, around 20% of us fail to hit the recommended daily dose of vitamin D. So, even with your summer escape plans grounded, catching rays should still be a priority – as long as suncream is involved. The good news is that you need just 20 minutes of sun a few times a week to reach your target. It’s an easy – not to mention pleasurable – investment in your long-term health.
Sleep
Getting outside in daylight every day could do more than top up your tan. NHS researchers say sunlight helps regulate serotonin (the hormone linked with mood) while also supporting your circadian rhythm, which plays a key role in sleep and brain health. Another Australian study found serotonin levels were higher on sunny days than cloudy ones, suggesting even one day of decent light exposure can make a difference.
Mood
Spending as much time as possible outdoors can make a lasting impact on your overall fitness, as well as on your short-term body goals. Researchers at the Massachusetts General Hospital found that exposing mice to sunlight for six weeks boosted their endorphins significantly, making them happier and more resilient to discomfort. Shift the dumbbells into the garden and you’ll be pushing out extra sets in no time.
But Make Sure You Use Sunscreen
A deficiency in vitamin D is a 'predisposing factor' in at least 17 cancers, reports the Cardiovascular Journal of Africa, but sun-related skin damage can also play a role – so it’s well worth taking sunshine seriously. The key is a 'little and often' approach: you don’t need us to rake over the well-known risks, but be aware that cases of melanoma are projected to rise by 7% in 15 years. The Skin Cancer Foundation recommends a water-resistant, broad-spectrum sunscreen with an SPF of 30 or higher for outdoor fun.
How Hot Is Too Hot to Exercise?
If the temperature is above 30°C you should take particular caution when training in the heat. Of course, this will depend on factors such as age, body mass, health status, experience and current fitness levels, as well as what you are used to and how well your body adapts to exercise in the heat. Some medications can also increase the skin's sensitivity to sunlight, so it's important to adjust training to suit your own needs.
You don't have to skip training altogether, but be sensible and pay attention to your ability to recover between sets. Don't be afraid to lower the exercise intensity if needed, take additional rest between sets and reduce your workout volume if necessary. If you experience dizziness or feel disorientated, stop exercise, rehydrate and try and seek cooler temperatures as soon as possible.
If there’s one thing Kori Sampson knows, it’s how to optimise your body composition for performance. To tap into his knowledge as an elite athlete and coach, we asked him to create a 4-week plan to help you move faster, recover quicker and keep pushing when the fatigue sets in – all while improving your muscle-to-fat ratio.
Ready to build muscle, burn fat and come out the other side looking, feeling and performing better? Click here to get 14 days of free access to the plan via the Men’s Health app.
Kate is a fitness writer for Men’s Health UK where she contributes regular workouts, training tips and nutrition guides. She has a post graduate diploma in Sports Performance Nutrition and before joining Men’s Health she was a nutritionist, fitness writer and personal trainer with over 5k hours coaching on the gym floor. Kate has a keen interest in volunteering for animal shelters and when she isn’t lifting weights in her garden, she can be found walking her rescue dog.
