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Why is exercising in heat difficult?

The British summer is unreliable at best and while you keep your fingers crossed for sunshine, scorching temperatures can make exercising feel like a chore.

If you've ever struggled during a run on a hot, humid day, you're not alone. There are several reasons why exercise can feel harder when it is warm. The optimum temperature for your body is 37°C, but both exercise and hot weather increase your core temperature - especially when you combine the two at the same time.

You have several mechanisms to help you cope with heat stress. First, blood vessels dilate to increase blood flow to the skin, which allows excess heat to radiate away from your body. Then you begin to sweat which cools the skin and subsequently the whole body.

However, cooling down is more difficult in humid weather because perspiration doesn't evaporate as quickly from your skin. This means your body has to work even harder to cool itself, which raises your heart rate too.

Don't take a holiday from exercising

Although it might feel challenging, it's important to stay active in the summer months. Not only is exercise good for your physical health, it decreases stress hormones such as cortisol and increases 'feel-good' endorphins. Physical activity also stimulates the release of the brain chemicals dopamine, norepinephrine, and serotonin, which play an important part in regulating mood.

Peter Hopson, a personal trainer based in Leeds, West Yorkshire says that it's important to stay active all times of year, even when it's hot and you don't feel like exercising.

"This is because, for fitness and health, consistency is key," he explains. "If it's hot for days and weeks and you put off exercise until it's cooler, you may be undoing all the hard work you have put in to improve your health and fitness up to that point.

"It may also lead to you stopping exercise completely as you get out of the habit. Once you've stopped it is much harder to get back going again. There are always ways to modify what you do in the heat."

What are the dangers of exercising in heat?

Although exercise is important, being active when it's hot does come with more hazards. Hopkins cautions that if you don't take reasonable precautions when exercising in the heat, the implications can be very serious.

"Dehydration, sunburn and heatstroke are all common problems. These can lead to much more serious issues," he says.

Dehydration means your body loses more fluids than you take in. If it's not treated, it can get worse and lead to serious complications such as heat exhaustion, heatstroke, seizures, and kidney failure.

There's also a high chance of heat exhaustion or heatstroke during hot weather or exercise. Heat exhaustion can occur after you've been exposed to high temperatures and is often accompanied by dehydration.

I heatstroke, your body can no longer cope. The normal mechanisms to keep your body cool stop working effectively, and your temperature soars to over 40°C.

Symptoms include:

• Svåra huvudvärk.

• Feeling or being sick.

• Shallow and fast breathing.

• Muscle weakness.

• Svimning.

• Förvirring.

However by taking certain steps, you can mitigate these hazards to stay healthy and comfortable when you work out.

How to stay active and safe

Stay hydrated

Making sure you're well hydrated before you exercise is really important, especially in hot conditions. If you're dehydrated before you start exercising, your core temperature will rise faster and your heart will have to work harder than usual. The current guidelines advise drinking six to eight glasses of water or other non-alcoholic fluid a day, but you'll need to drink more if exercising.

The amount you need to drink will depend on how much you sweat and how long you exercise for. Other factors can include your fitness level, environment, and the intensity of your workout.

"To mitigate the hazards you can reduce the intensity and duration of your training, and ensure you're well hydrated before, during and after," Hopson says.

Try different types of exercise

If you're not in the mood to run when it's hot, there are plenty of other types of tränings you can try. Try lower-intensity exercise, such as yoga or Pilates, or go on a walk to make the most of the clement weather.

"All varieties of exercises are great in summer," says Hopson. "You can take advantage of the warmer water with open water swimming, stand-up paddle boarding, or kayaking. It's also great to take advantage of the nicer weather to get out hiking in the hills."

Avoid the hottest part of the day

Hopson recommends trying to stay in shady areas, such as woodland or near buildings.

He adds: "You can also use air-conditioned facilities. Most major gyms have adequate AC these days. Apply sunscreen if you're going to be in direct sunlight."

Cool down your skin

It's also important to think carefully about your clothing if you're exercising in hot weather. Loose, light-weight, sweat-wicking clothing can be more comfortable than tight sportswear. Remember, wearing black can often make you feel warmer too.

If you do feel too hot, applying cool water to your skin can help you feel better. Cold packs, cold wet towels, or water sprays can help you feel more comfortable.

Take it easy

And remember, exercising can just feel hard sometimes - especially when it is hot and humid. Don't push yourself too hard and bear in mind that less can be more.

"Most importantly be mindful of how your body feels and be prepared to cut your session short if needed," Hopson concludes.