Famous biologist Bernd Heinrich described us as ‘thermal warriors’, unique among all living animals for our ability to manage high temperatures when running. With peak summer looming, it’s time to gear up for battle; and that means adapting your body to the challenge of the heat.

Fortunately, our physiology has a few tricks up its sleeve, some of which are (very) long-term, and even go as far as to change the shape of our bodies: people who evolved at the equator, for example, tend to be taller, with very long arms and legs relative to their height. That’s because being ‘elongated’ helps the body to act like a radiator, increasing the surface area to assist with heat loss.

This is may be part of the reason why Kenyans are such great runners; their long, skinny legs help them run more efficiently, but they also help keep them cool.

But that takes generations… we have weeks.

THE ADAPTATION

Luckily, there are short-term adaptations we can advantage of if we’re aiming for a PB this summer. The main one is our capacity to sweat. Sweating helps our bodies to lose enormous amounts of heat, so the better we do it, the cooler we stay. That’s good, because science has shown that once the body temperature reaches a critical ‘cut-off’, our day is done.

The brain basically shuts us down, and we can’t send signals to our muscles any more. That’s why one of the classic signs of over-heating is that we look ‘drunk’, unable to move our limbs in a co-ordinated way. The hot brain is ‘failing’ us.

The fitter we become, the more we sweat, and the more our plasma volume increases, which means we have a bigger capacity to lose heat. We also learn to tolerate that unpleasant ‘hot’ feeling – and perception is a critical part of being a better hot-weather runner. This is why pouring cold water on yourself may help; it doesn’t actually lower your body temperature – but physiologically speaking, perception is reality, and so it’s worth doing.

THE TIME

Research shows we can adapt within a week, but only with really aggressive strategies. For instance, one study had non-acclimatised athletes exercise to exhaustion in a hot environment, for six consecutive days. On day one, the athletes barely made it to 20 minutes before their body temperatures and exertion maxed out. But by the end of the week, they were running for an hour.

However, running to exhaustion is neither fun nor advisable, and it’s also not a good idea to stress yourself out like that every day. Just like you wouldn’t go out and smash consecutive long runs or interval sessions (I hope), you shouldn’t expose yourself to heat too often – it’s just too risky.

THE STRATEGY

If you know a race is coming up, and you want to be in a good condition for it, try the following:

• First Two Weeks: Three runs, at least three days apart, of between 20 and 30 minutes in warm temperatures. Don’t worry about pace. Just get your body to feel the heat, so that it kicks in the physiological adaptations.

• Week Three: Two runs, up to 40 minutes, with at least two days rest in between. Pace becomes more important – if you’re training for a half marathon, for instance, these can be at race or tempo pace.

•Week Four: Three runs, at least one day apart, where you do what you’d consider ‘normal’ training. By this time, you should be feeling like you’re getting on top of the challenge.

From then on, running once or twice a week in hotter temperatures should help to maintain the adaptation. Planning on racing in the heat? This strategy is the difference between hitting goals and being flattened by temperatures – it’s definitely worth a try.

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