What athletes at the Olympic Games in Tokyo reveal about heat waves and climate change

This summer’s Olympics could be the warmest in decades. Tokyo, where the games take place, can have dangerously high temperatures of over 90 degrees.

The athletes will likely be prepared. Scientists like Oliver Gibson, an exercise physiologist at Brunel University in the UK, have spent decades studying how athletes can adapt to extreme heat conditions. He says that through exercise, the human body has a remarkable ability to cool itself down when the temperature rises.

Today, however, Gibson is less concerned about the athletes. Running a marathon in 90 degree heat can be dangerous, even with preparation, but there is a much greater threat to ordinary people coping with the new realities of climate change. “A lot of what we’re doing now is applying the decades of knowledge we’ve gathered from athletes to the general population,” says Gibson.

Dealing with heat stress is a growing problem that “will affect more than just your dozen or more Olympic finalists,” he says. “Millions, billions of people will undoubtedly be affected by climate change.” Heat emergencies are already the deadliest weather event and are likely to get worse. To beat the heat, we’ll have to face it, says Gibson. He believes research into top athletes could help make our bodies more resilient in a warming world.

This conversation has been edited for length and clarity.

Brian Resnick

Can everyone adapt to the heat or are they just top athletes?

Oliver Gibson

Yes, everyone can adapt to heat. We recently published a paper on elderly UK residents who were exposed to very little heat. We asked her to exercise on the treadmill for a short time. And then [they sat] in a warm bath to keep their body temperature high. What we’ve shown is that they can adapt to the heat within five days [under the supervision of medical professionals].

Brian Resnick

What do you mean by adapting to the heat?

Oliver Gibson

What we are trying to do with heat adaptation is to improve the baseline of the body. When an athlete trains in the heat for two weeks, we know that their core body temperature drops by about 0.5 degrees Celsius on average. Some a little more, some a little less.

What that does is lower the existing body temperature so that when they inevitably warm up, they have a bigger window. You can keep exercising until you have increased by that amount.

And then a body begins to sweat earlier. Only a small change in temperature triggers sweating. And the signal to sweat will also come with a greater magnitude. This way it won’t sweat a bit later; it will be faster to sweat maximally. The rates of dehydration will be higher and faster.

Brian Resnick

Can athletes adapt better to the heat?

Oliver Gibson

Athletes have earned their advantage through years of training. They have more blood so they can pump that blood around the body more effectively. So you are not restricted in this regard; they have a larger heart, which generally beats more often, so that their cardiac output can respond to the heat.

For the general public, it may take three or four heat exposures to even see any signs of adaptation. While an athlete is exercising regularly, the adjustment is right there.

People previously exposed to heat stress can induce the same level of adaptation more quickly. So if you’ve already been in a warm environment, you will adapt a little faster.

Brian Resnick

I’m curious to learn some of the basics here. How does the human body normally deal with heat?

Oliver Gibson

The human body is very effective at dissipating heat. We are the very best mammals – the best beings – to sweat on the planet. So when someone exercises in very cool or even moderate conditions, they can sweat enough to lose heat. As long as they aren’t exposed for too long or become very dehydrated.

Brian Resnick

What happens if they are exposed for too long?

Oliver Gibson

As soon as the body temperature rises, we see an increased distribution of blood on the skin. Blood vessels open. When someone gets warm, you can see this reddening of the skin.

And when a drop of sweat evaporates from the skin, the space below, the blood, is cooled. Cooler blood circulates and cools down in the body.

Brian Resnick

But this system sometimes fails.

Oliver Gibson

We don’t have this infinite ability to increase our cardiac output or the amount of blood pumped by the heart. We come to a point where there is insufficient cardiovascular response to cool us off optimally. And at this point the body temperature begins to rise.

For many people, the challenge arises when movement and warmth are combined. The challenge with exercising is that you have competing demands on that blood supply: from the skin to cool down, but also from the muscles for this activity in motion.

It gets worse when the environment is warm and humid, so when the sweat leaves the body it drains more slowly so there isn’t as much cooling off. If the surface is 100 percent saturated, the humidity is very high, then all the sweat drips onto the floor and does not provide this evaporative cooling.

Brian Resnick

What’s the worst case scenario?

Oliver Gibson

A clinical diagnosis of hyperthermia comes from high body temperature and neurological dysfunction – effective when the brain gets too warm. We have this region of the brain called the hypothalamus, which is our thermostat. And the high temperature can actually disrupt this processing system, so our bodies would actually go backwards and we would actually stop sweating. The signal is confused by extreme heat. It’s an almost fatal condition.

Brian Resnick

What I am hearing here may be: Good cardiovascular health will be important for people who adapt to a warming world in order to cope with worse heat waves.

Oliver Gibson

Necessarily. Someone – especially those in their middle to late stages of life – with a more robust cardiovascular system will generally have a more resilient body, whether it be to the challenge of temperature or other things thrown at it.

Brian Resnick

Often times during a heat emergency, the public health message is to stay indoors as much as possible. And I think that’s helpful because a lot of people are not adapted to the heat.

But if we see heat waves becoming more common, could we benefit from facing a little more and adapting?

Oliver Gibson

I think my philosophy is that the body can react to heat stress. So as long as we take it moderately and handle the heat with skill, we shouldn’t be in a situation that we can easily avoid. Taking on the stress is absolutely the right approach.

Brian Resnick

Could it be dangerous to adjust to the heat? There’s a bit of a riddle here: in order to cope better with heat, we have to train in the heat, but the heat is dangerous if we are not trained.

Oliver Gibson

If you want to adjust to the heat, it is important to listen to your body and do things gradually and slowly. We’d never say you shouldn’t try to adjust to the heat. But going out and being a little arrogant or smug would put you at great risk in my opinion. We therefore always recommend doing things with moderation. If you’re not already involved in exercising regularly, this is probably the very first step before you start adding heat to the mix.

But if someone is used to exercising – even if that is brisk walking – it shouldn’t be too much of a risk in a warmer environment as long as you listen to your body. And the moment you feel like you’re overheating – if you start feeling lightheaded, if you are uncomfortable in any way – call back right away, find shade, make sure you are hydrated.

We’d like to say that recreational athletes might have the same amount of time running in the heat, but turn the intensity down a bit. Recalibrate your expectations until you see the adjustments. So once you find that you are sweating more – and when you measure your heart rate, if it could look like this in cooler conditions – it’s a good sign that your body has started to respond. You can push a little harder.

Brian Resnick

Do you have any general tips to help people cope with the heat when they may be less well adapted to it?

Oliver Gibson

Drink frequently. Have a planned drinking strategy and a cool drink with you. Then the other thing is to make the skin cool. In addition, you can of course look for shade and air conditioning. Even if that’s not available, don’t be afraid to rub exposed parts of your body – arms, legs, face – with very cold water. It’s something incredibly simple.