Key Points
- As summer weather sets in, many people are exercising in the heat.
- Experts highlight the serious danger of prolonged exertion in extreme heat.
- When your body starts to heat up, your organs start to come under strain, and the brain suffers first.
Sydney just experienced in more than 160 . On Thursday the temperature reached a peak of 38.9C in the city and a scorching 40.3C at the airport by 4pm.
The heat wasn't enough to deter a group of regulars at the outdoor gym at Sydney's Bondi Beach, who embraced the challenge of maintaining their workout routines under the blazing sun.
One of the regulars, Stan, said that he usually worked out at the gym three to four times a week, regardless of the weather.
"Actually, I enjoy the heat because you sweat more, so you need to make less effort, but you get more out of it," he said.
"Set your goals and go after them. Don’t let the environment put boundaries on you!"
Bondi outdoor gym is typically bustling even on the hottest days. Source: SBS News
"You can use the high temperature as an excuse not to work out, but really, at Bondi, by the beach, it’s never too hot."
Athletes and fitness enthusiasts are used to physical discomfort and pain and many seek to push their physical limits. For some of them, it includes conquering extreme heat.
For those people, medical experts have some words of warning.
Dr Simon Quilty is an ANU specialist physician and heat researcher. Credit: Australian National University
He said that when he was younger, he also didn’t understand the full dangers of physical activity in the heat.
"There was one day that I nearly perished on the edge of the Western Desert," Quilty said.
"And there were certainly a number of days where I really pushed to the limits. For instance, riding my push back home 15 kilometres after work on a 36C day I realised that I was actually doing myself damage."
As more research on heat is coming out, Quilty said, it’s becoming clear that regular prolonged exposure to exertion in .
"That’s something that we’ve only known about over the last five or six years," he said.
"This problem of extreme heat and how it interacts with our bodies is something that’s really only starting to come under investigation," he said.
Sydney just experienced its hottest first fortnight of summer in more than 160 years of records. Source: AAP / Brent Lewin
The brain suffers first, impairing clear thinking
When your body starts to heat up, your organs start to come under strain, Quilty explained.
And one of the first organs to be affected by the heat is your brain.
"The bad decision of going for a run on a very hot day in the first place will actually turn into a cascading series of worse and worse decisions that could ultimately result in death," he said.
Those bad decisions include not only not listening to your body signals and continuing to push through, but even crossing the street at the red light or putting yourself in other dangerous situations.
What are the signs you pushed yourself too hard?
Feeling very hot and thirsty is not just a normal reaction of your body to the heat; it means you can be in danger because then you can start to feel confused.
"That makes it much harder for you to differentiate what's actually going on with your body. Some people start feeling like they have a fever or they get goose pimples on their body.
"The muscles can start to ache. And that can be the beginning of rhabdomyolysis, literally when your muscles get so hot that they start to melt down. And that is the beginning of the dying process," Quilty said.
Rhabdomyolysis is a serious condition caused by the chemicals from muscle breakdown entering the bloodstream. It can be fatal or result in permanent disability.
Fit people are also vulnerable to the heat
Quilty emphasized the crucial role of baseline health status, noting that individuals who are more physically fit are far more likely to endure higher temperatures for longer periods. In contrast, those with certain medical conditions or who are older (from 55 on) may encounter difficulties more rapidly.
Still, if you consider yourself young and healthy, it doesn’t mean your body’s adaption abilities are limitless.
"For people that are going to exercise and really exert themselves in the heat, I have some words of warning," Quilty said.
"I very clearly remember a very young, fit man doing a long competitive run in Katherine in the Northern Territory. It was in the middle of the cool season, but it was still 33 degrees that day.
"And he ran fast and hard. And he collapsed. He got rhabdomyolysis, and all his muscles melted. And he had to be medically evacuated up to Darwin, where he went to the intensive care unit.
"This can happen to young people who fit and well. Just because you really fit and well doesn't mean that you're not very vulnerable to the heat."
Our bodies adapt, but it takes time
Our tolerance for high temperatures is significantly influenced by the climate of our origin.
People who live in a hot climate should be reasonably well acclimatised to heat, but not if they spend much of their time in air-conditioned places that are much cooler than the outside temperature.
"The more you extract yourself from the environment in which you live, the less your body will adapt," said Quilty.
"We know that people that spend more time in air conditioning are more prone to heat shock, in very hot weather."
Quilty said considering climate change and the prospect of hotter weather, people should start paying more attention to how they adapt to the heat.
"Particularly in hotter climates like Brisbane, people shouldn't be setting their air conditioner to 21C, they should be thinking about setting it to 26C or even 27C. This takes the humidity out of the air. And it makes you feel comfortable enough."
So, instead of going for a run after work, where you've been in a comfortably cool room all day, Quilty suggests jogging early in the morning before the sun rises.
Instead of going for a run after work, where you've been in a comfortably cool room all day, experts suggest jogging early in the morning before the sun rises. Source: AAP / Michael Probst
"Then doing things like drinking plenty of cold water to keep your core body temperature cool. And also just being aware that extreme exercise or even moderate exercise can be very dangerous, it can actually kill you. And recognising that it really is a potentially very serious thing to do to go exercising in the heat of the day."
