Summer Exercise: Dealing With Heat Associated Illness

Whether you play any sports or just enjoy regular exercise outdoors there is a risk of sustaining a heat associated illness when temperature and humidity are high.

As we head into the warmer months of the year, we felt it worth reviewing the different types, symptoms and management of heat associated illness.

Heat illness covers a broad range of conditions including heat stroke, exercise associated collapse (heat exhaustion) and heat cramps. To gain a better understanding on these conditions we will begin by reviewing how the body works in regulating its temperature.

What is heat stress and how does the body regulates its temperature?

Heat is produced by both internal sources within the body (eg. Metabolism) and external sources (the environment). Heat loss occurs by several methods including convection and evaporation. When a person starts to exercise and produce more heat,  evaporation of sweat is the primary method by which heat is lost. When the body is no longer able to cope with increasing temperatures, the result is heat illness.

What are the different types of heat associated illness?

Heat stroke

This is the most serious and occurs DURING exercise, when a person shows signs of a decreased level of consciousness or marked changes in mental function (such as collapse, increased irritability etc.) and an associated increase in temperature above 41 degrees Celsius.

Other symptoms of heat stroke include dizziness, weakness, nausea and headache.

Exercise associated collapse ‘heat exhaustion’

Occurs AFTER exercise when a person shows signs of a decreased level of consciousness or marked changes in mental function (such as collapse, increased irritability etc.). This is caused by a drop in blood pressure. It is important to note that in this condition, body temperature is raised only slightly. Therefore the collapse is not caused by elevated temperatures, but rather a drop in blood pressure that develops in people who exercise in the heat.

Heat cramps

The jury is still out on the cause of this but the most current theory suggests that cramps result from changes in reflex activity coming from the spine which is activated by fatigue in susceptible individuals (such as those exercising in hot conditions).

What factors can increase the risk of heat associated illness?

  • Increased humidity – In dry conditions evaporation of sweat can occur effectively. In humid conditions where there is high level of moisture/water vapour in the environment; evaporation is less effective and limited. Thus the combination of high temperatures and humid conditions predisposes a person to higher risk of heat illness.
  • High air temperature.
  • Low wind speed.
  • High intensity exercise close to maximal capacity.
  • Large amounts clothing and protective gear.

Ways to prevent and minimise heat associated illness

  • Modify warm-up (shorter warm up in hot and humid conditions).
  • Ensure there is an appropriate amount of training and conditioning for the planned activity including  a period of heat acclimatisation.
  • Wear appropriate clothing (minimal amount of loose fitting light coloured clothing). This allows for effective evaporation of sweat.
  • Drink appropriate amounts of fluid before the event.
  • Avoid exercising in the hottest part of the day.

How to deal with heat associated illness

A qualified health professional is best able to assess the athlete as and implement the appropriate management plan based on individual circumstances. If you suspect someone is suffering from a heat associated illness then you should:

Heat Stroke
  • Cool the patient down by applying ice packs to the groin, arm pits and neck or if available place the athlete in an ice bath to reduce the temperature to 38 degrees Celsius (note the most accurate measurement of body temperature is obtained from the rectum and this should be performed only by a qualified medical professional).
  • Remove excess clothing.
  • Give the patient water if they are conscious.
  • Closely monitor the patient and if signs and symptoms persist an ambulance should be called.
Heat exhaustion
  • Lay the patient down and elevate their legs.
  • Remove excess clothing.
  • Give patient water or a sports drink if they are conscious.

For more information on heat associated illness contact one of the physiotherapists at Jubilee Sports Physiotherapy.

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