Advice on Heat Injury for Runners

Dr Mike Berry MD, MRCP (UK)Consultant Respiratory Physician

Honorary Senior Lecturer in MedicineUniversity Hospital Birmingham NHS Foundation Trust Selly Oak Hospital Birmingham

Heat Injury for runnersDying for a marathon PB?

During the heat this spring/summer be aware of the risk of heat injury. Previously called heat exhaustion and heatstroke this is a preventable but potentially fatal condition that

occurs when the body’s ability to lose heat is overcome.

Cramps

Thirst

Profuse sweating

Clamminess

Nausea

Vomiting

Confusion

Disorientation

Coma

Death

Symptoms of heat injury

Thirst

Many runners stick to the wisdom that “If I listened to my body I would never get out of the door”, but thirst is one thing your body will tell you that you should never ignore. Skipping a drink station because you don’t want to drop off your time schedule is a fools game, as dehydration and heat illness progress you will certainly drop off your schedule.

Cramp

Cramp is a symptom of fluid and electrolyte depletion. When running in hot weather use an electrolyte additive, such as diarrolyte or Nuun, in you water bottle.

Nausea

Nausea is a very worrying symptom and indicates the onset of serious heat injury. STOP. 70% of the energy you are generating from running is heat. Continue running now and you are putting yourself in danger. Try to actively cool yourself down, use cold water or

wet towels. If at the end of the race lie down and elevate you legs.

Vomiting

Vomiting obviously prevents adequate rehydration and cooling. If this does not settle then seek medical help immediately: intravenous fluid may be necessary to prevent

more serious heat related injury.

Profuse Sweating

Sweating, or more specifically evaporation of sweat, is the body’s natural way of cooling. If you wear too much clothing this will make evaporation and hence cooling less efficient. Profuse sweating associated with a high heart rate even after cessation of exercise and heat exposure is a worrying symptom and suggests the body has lost

its ability to regulate heat.

Clammy Skin

While exercising the skin is usually flushed as the body tries to dissipate heat. If the skin is pale and clammy while sweating this is also a sign of failure of the body’s heat

regulation and may indicate shock. In this case emergency medical assistance is required.

Confusion

Confusion due to heat illness indicates severe disease and the athlete is at risk of developing organ failure. If no medical facilities are available at the event dial 999. Try to

cool with cold towels and if not vomiting drink sips of cool liquid.

Disorientation

Disorientation is a late symptom and it is likely the athlete already has organ damage. Dial 999 and follow advice given by the operator.

Coma

Coma occurs as a consequence of the failure of multiple organs, typically kidneys, liver, lungs and brain. Failure to regulate body heat results in very high body temperature

and a high risk of death.

Death

Heat injury is the 3rd leading cause of death in training athletes.

Heat Injury Prevention

Conditioning

The fitter the better

The fitter you are the less likely you are to develop heat injury

Body Composition

The less fat the better

Fat acts as an insulator and prevents heat loss therefore making heat injury more likely

Acclimatise

Practice in the conditions you are going to race in

If possible light to moderate exercise in conditions similar to those you are racing in reduces the risk of heat injury.

Pre-Hydrate

This is the one you are aiming for

Make sure that you are sufficiently hydrated before the race that your urine is almost colourless

Avoid Drugs

This is not the secret of fast running!

Many common drugs make heat injury more likely, alcohol through dehydration, caffeine through dehydration and increased heart rate and metabolic rate.

Maintain hydration

You might not look this good drinking!

Drink to thirst during the race – take the time to think, am I thirsty?

No Sweat Barriers

Speedos good, hats bad!

Wear minimal clothing to expose the maximum surface area for sweat evaporation & don’t worry what you look like.

Everybody Stay Cool!