Hooray, summer is here. It’s great to see people out and about and getting active now some summery weather has returned, but also a good opportunity to remember how to manage being active safely in the hotter weather.

Call it what you will, but there are some seriously hot weather patterns around in amongst the other extreme weather events, and this can seriously affect how your body and mind function while exercising. Recall the recent US Open? “Soaring” heat and humidity levels caused the implementation of heat regulations and extra breaks for the players, and remember the Scottish marathon runner who collapsed 2km from the finish with a 22-minute lead during the 2018 Commonwealth Games? Another shocking statistic is that, despite all the recent knowledge around heat illness, there are still on average 3 deaths per year in American Football from heat stroke – often adolescents / young adults in pre-season training trying to impress the coach. Clearly then there are some specific health issues to exercising in the heat.

Caution should be applied if an athlete can tick any of the below risk factors, and especially so if a number of them apply:

  • Hot and humid weather – heat index measures.
  • Current illness – e.g. respiratory or gastro – and don’t EVER exercise with a fever, whatever the conditions.
  • Dehydration (e.g. from above).
  • Previous heat illness.
  • Poorly acclimatised.
  • Overweight and low fitness level (interesting fact: muscle is a much better insulator than fat – but fat is far easier to accumulate)
  • Medication – e.g. antidepressants, or tramadol.

If heat illness does occur, then recognising and appropriately treating it promptly could save their life. Rapid cooling is the key (e.g. place in the shade; immersed in water; water sprayed while in front of a fan; ice packs to the large blood vessels – neck, axilla, groin). Anyone suspected of a heat illness needs to be sent for medical assessment, as heat will denature proteins / affect cell function, resulting in challenges to a number of organs – e.g. potential renal failure with rhabdomyolysis.

Exercising in the heat costs the body more energy as it works to cool itself. Hot, sunny, humid and still days are challenging for the body to lose heat in. In those who are acclimatised to the heat, the body starts sweating earlier, the sweat has fewer salts in it, and the body is much better at shunting blood to exposed skin areas to improve heat loss. Appropriate training in the kind of conditions you are expecting when undertaking an event will help get the body efficient at these cooling mechanisms. Another potential “mechanism” of coping in the heat is exposing the mind, and its “central fatigue” regulators, to activity in the heat – thus maintaining motivation to exercise and reduced signal of “fatigue” to the conscious mind, so you can keep on going. This is a theory, but certainly something the elite athletes undertake in preparing to perform in the heat.

So how can you prepare for performing in the heat?

That is something to really work on with a coach and physiologist, but some common ways to prepare for the heat are:

  • Increase fitness – HIIT (high-intensity interval training) twice per week.
  • Short bouts of exercise in the heat / sun - e.g. training in the middle of the day – a good time to practice your nutrition / fluid strategies as well, as it is often hard to consume calories in the heat.
  • Exercise with warmer clothes on, or indoors with the heater on. 

More specialised preparation includes using heat chambers where temperature and humidity can be controlled. For events in hot climates overseas, heading to the area 2-3 weeks in advance of the event to fully acclimatise by training in the conditions is ideal. There is some discussion around using a sauna or spa pool immediately following exercise to adapt the body to hot conditions – via activation of Heat Shock Proteins – again this is something to discuss with your physiologist.

How to cope in the heat?

Here are some of our top tips.

  • Don’t expect to produce best times in hot conditions – your body will be expending energy to cool itself.
  • Undertake some training in the conditions you are expecting.
  • Maintain good hydration up to the event.
  • Apply sunscreen well before your warmup – sunscreen attaches poorly to sweaty skin.
  • Keep in the shade when you can.
  • When exercising, drink to thirst.
  • If being active over 90 minutes then appropriate calorie intake every 30 minutes.
  • Wear a sun cap which covers the whole head, and one you can put ice into the “crown” of the hat.
  • Water cups over the body at aid stations, you won’t be the only one doing this.

Above all, prepare for the heat, keep well, look out for others who are finding the heat challenging, and enjoy a safe and active summer.

By Dr Brendan O'Neill on