Exercising in the heat – what happens, the risks and tips to protect yourself


Training in extreme climates can cause additional stress to the body on top of exercise demands. We would like you to be able to perform in any conditions, even when summer is in full swing. However, there are certain risk factors associated with exercising in high temperatures and extra precautions you need to take.


What is the physiological response to exercising in the heat? 

We have heat receptors in the skin which send signals to our hypothalamus in the brain. The hypothalamus also harbours neurones that detect core body temperature changes.

Exercise itself will increase your body temperature, something we can physically feel as we progressively ‘warm up’. However, it is your core body temperature we are really concerned about. Your temperature is impacted by exercise intensity, the air temperature and humidity in the air.



What are the risks if these two systems fail?

When we are exposed to the heat for long periods of time, with high perspiration levels and without enough water, we are likely to get dehydrated. This is the beginning of a series of events which can become serious, dangerous and potentially life threatening. Remember to drink at least 2 Litres a day!

Dehydration can lead to the following:

  • Heat cramps

These are often due to fluid and electrolyte loss but involve an involuntary muscle spasm. They are more intense and prolonged than your typical night time leg cramp. Muscles commonly affected include your calves, arms, abdominal wall and back.

  • Heat syncope and exercise-associated collapse

This is a sudden drop in heart rate and blood pressure due to a malfunction in temperature control. Blood pools in the legs, leading to a lack of blood to the brain. This causes; light headedness, tunnel vision, nausea, cold clammy sweats, blurred vision and eventually fainting.

  • Heat exhaustion

Your body temperature during heat exhaustion rises to 40 degrees C. Your pulse will rapidly increase with heavy sweating as a result of your body overheating. Causes include high temperature and humidity exposure combined with strenuous physical activity. Without fast treatment heat exhaustion can lead to heatstroke.

  • Heatstroke

If your body reaches 40 degrees C or above, you are at extreme risk of suffering from heat stroke. It can lead to an altered mental state, distorted sweating, vomiting, flushed skin, racing heart rate and a headache. Complications include vital organ damage due to swelling and in extreme circumstances can lead to life threatening, irreversible consequences.


Tips – what you can do to protect yourself when exercising in high temperatures.

  • Wear moisture-wicking clothing – these fabrics will help draw moisture away from the body
  • Acclimatise to the weather by slowly building up training
  • Always have hydration at hand
  • Avoid caffeine before exercise
  • Closely monitor your heart rate
  • Exercise in the early morning or evening