Health conditions

Heat stress when exercising

The combination of hot weather and the heat your body produces when you exercise can create dangerously high body temperatures, leading to heat stress.

Find out more about heat stress, including signs and symptoms.

Who is at risk?

Anyone exercising in hot weather – including people with a high fitness level – increases their risk of heat stress. There is also the risk of developing a serious condition called exertional hyperpyrexia, which could result in your collapse or even death.

Early signs of exertional hyperpyrexia include slurred speech and lack of coordination.

Generally, women face an increased risk of heat stress because of their greater percentage of body fat compared to men.

Heat stress can also affect children when they exercise, especially intense or endurance activities like football.

Find out more about protecting older children and teenagers from heat stress.

Prevent heat stress when exercising

In addition to general advice to prevent heat stress, the following can help reduce your risk of heat stress:

Be sensible about exercise

  • Aim to exercise very early in the morning or at night when the temperature is cooler.
  • In hot conditions, reduce the time you spend warming up, and exercise at a slower pace.
  • If you exercise outdoors during the heat, try to find some shade.
  • Have a back-up plan so you don’t have to exercise outdoors during hot weather. Work out at an air-conditioned gym, walk laps inside a shopping centre or climb stairs in an air-conditioned building.
  • Don’t exercise if you feel unwell or are recovering from recent illness.
  • If you start to feel ill while exercising, slow down or stop.

Drink regularly

  • Drink plenty of water before and during exercise. Aim to drink at least 2 to 3 litres of water a day during hot weather.
  • Sports drinks are specifically designed to help hydration, as they help replace the sodium, chloride and potassium you lose through sweating.


  • Wear light-coloured, lightweight and loose-fitting clothing. Your clothes should provide protection from the sun and allow easy evaporation of sweat from the skin. Cotton fabric is often a better choice as it absorbs sweat and is not usually as irritating to the skin as nylon or synthetic fabrics.
  • If possible, wear a wide brim hat that covers your head and shades your face. Caps do not provide adequate sun protection.
  • Wear sunglasses.


  • Apply sunscreen at least 20 minutes before exposure to the sun so it can be absorbed into the skin and provide effective protection.
  • Reapply sunscreen as instructed on the bottle. In general, this is every 2 to 3 hours or more often if you are sweating heavily or swimming.

Where to get help

  • If you have severe symptoms, always dial triple zero (000) to call an ambulance in a medical emergency
  • See your doctor
  • Visit a GP after hours
  • Ring healthdirect on 1800 022 222


  • Exercising in hot weather can increase your risk of heat stress.
  • Reduce your risk – drink regularly, exercise in the coolest part of the day and wear appropriate clothing.

Disaster Preparedness Management Unit

This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.

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