The expert advice on exercising during a heatwave

The most severe heatwave in Australia since the 2019-2020 Black Summer has failed to deter many people from their exercise routines.

Despite the extreme weather conditions across south-eastern Australia sending the mercury over 40 degrees, many dedicated exercisers have been spotted working out.

But is it safe, and what should you beware of?

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Prepare for the heat

Even fit people are at increased risk of heat exhaustion or heat stroke when the mercury climbs.

Sports Medicine Australia (SMA) chief executive Jamie Crain advises exercisers to take increased precautions to guard against heat exhaustion or the more serious heat stroke.

"During times of extreme heat, it's vital for people exercising to take precautions over and above what they would on a temperate day," he told 9news.com.au.

They include limiting activity times to the cooler periods of the day, such as early morning and evening.

It's best to avoid the warmest hours, from 10am to 3pm.

Maintaining hydration is essential, and during extreme heat you should keep sipping water even if you don't feel thirsty.

On very hot days, the SMA advises drinking at least 500 millilitres of water in the hour before taking exercise. And caffeine, including coffee, should be avoided in the hours leading up to working out.

If you're outside, remember to wear sunglasses, sunscreen and a wide-brimmed hat.

Choice of clothing is also important. Where possible, select lightweight and breathable clothes with extra ventilation.

For those taking exercise indoors, try and find a location with air conditioning.

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Signs of heat-related illness

Crain says the health impacts of heat-related illness can be a direct result of an increase in core temperature or the result of the strain on the heart associated with combating the jump in body temperature.

"If anyone experiences nausea or vomiting, that is a sign they need to cease exercising and take immediate action to cool down," he said.

Other symptoms of heat exhaustion include dizziness, cramps, headache and general weakness.

Anyone experiencing these should move immediately to a shaded area, remove as much clothing and protective equipment and rehydrate.

Crain says more serious warning signs such as slurred speech, impaired decision making and poorer brain function indicates heat stroke.

"That requires immediate medical attention ... straight away you'd be calling for medical help ... trying to cool them down with something like an ice bath," he said.

While even elite athletes are at risk from heat-linked conditions, some people are at more risk than others.

They include those aged over 65 years, especially if unfit. The SCA cautions that age effects on thermoregulation, the body's process of controlling internal temperature, may become progressively worse with age.

The risk of falling victim to heat stress is also greater among heart or kidney disorder patients.

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