How to exercise safely in hot weather

Soaring temperatures could put people's long-term health at risk by stopping them from exercising, scientists warn. Here's how you can keep going when things hot up.

Staying active in hot weather can be challenging. It's one reason why players at the World Cup 2026 in the US, Canada and Mexico are being given additional, but controversial hydration breaks 22 minutes into each half. And with record temperatures on their way this summer thanks to a powerful El Niño weather pattern, it's likely to be a tough time to exercise.

Pushing through a run or football match in extreme heat can not only be uncomfortable but also dangerous, putting us at risk of heatstroke.

"Walking, cycling, exercising outdoors and even daily routines like commuting on foot become more physically demanding and less comfortable when temperatures are high," says Christian García-Witulski, an environmental lifestyle epidemiologist at the Pontifical Catholic University of Argentina.

But if we reduce our physical activity each time it feels too hot to exercise outside, it can contribute to long-term health risks.

García-Witulski and colleagues have recently warned in new research that rising temperatures due to climate change could lead to people moving less in the heat and consequentially result in an estimated 470,000 to 700,000 premature deaths per year by 2050.

Why you get tired quicker in the heat

As you work out, your muscles contract and generate heat. Your body then tries to cool itself by sweating and diverting blood towards the skin.

But that creates a trade-off as the same blood is also needed to supply oxygen to your muscles, says Ollie Jay from the University of Sydney. "Your skin is basically robbing blood from your muscles, so you can't deliver as much oxygen to them."

In hot conditions, can very quickly lead to fatigue as your body struggles to get enough oxygen to your muscles, but it can also put extra strain on your heart as it tries to keep up with the demand.

So how do you safeguard your long-term health by staying active when it gets really hot? Here are some of the strategies that researchers say might help you stay cool while staying active:

The single most impactful change most people can make is to exercise when it is cooler, such as in the morning or evening, if this is possible.

You could also pick times when the area where you like to exercise is in the shade as opposed to the full glare of the Sun. "That difference can be as much as 12-15C (22-27F) higher than the shaded air temperature," says Ollie Jay, director of the Heat and Health Research Centre at the University of Sydney.

Humidity matters too. Your body's primary way of losing heat is through sweat evaporating from the skin, which helps to lower your body temperature. But in humid conditions, that process is affected as the evaporation that cools your body reduces. 

"There's more moisture in the air and therefore the [evaporative] driving force is blunted," says Jay.

Wind speed also plays a role, which is why running........

© BBC