Heat Related Injuries in Extreme Desert Conditions

29 April 2009

Operating in extremely hot conditions creates a unique set of medical risks. In the link is the medical outline – for non medics, regarding those risks from the Namibia Ultra Marathon training guide.

Dehydration is the most common heat related illness – in fact, it is thought that dehydration could be the single greatest threat to the health of an athlete. When training regularly and for long distances, fluid intake should be made a priority. You must drink fluids all day – not just during training.

Don’t depend on feeling thirsty to tell you when to drink. Thirst is a late response of the body to fluid depletion. Once you feel thirsty, you are already low on fluids. The best indicator of proper fluid levels is urine output and colour. Ample urine that is light coloured to clear shows that the body has plenty of fluid.

Dark urine means that the body is low on water, and is trying to conserve its supply by hoarding fluid which means that urine becomes more concentrated (thereby darker).

Dehydration can be the cause of feelings of fatigue or exhaustion – at all times watch out for signs of dehydration and take on water regularly through out the day.

Signs of dehydration are as follows:

• fatigue
• dizziness or confusion
• headache
• decreased urine output and a darkening of colour
• heartburn or stomach ache
• recurring or chronic pain
• lower back pain
• dry or sticky mucus membranes in the mouth
• mental irritation or depression
• water retention
• lack of skin elasticity
• sunken eyes

Fluids & Salts:
Another factor in overall fluid balance is the replacement of salts lost to sweat. Sports drinks contain carbohydrates and sodium which will help you to replace lost electrolytes. When training long distances, and during the race, you must bring sports drinks containing sodium to be included in your fluid intake to ensure you remain suitably hydrated.

Your body absorbs fluids best when you drink frequently and in small amounts rather than drinking large amounts at one time. It also helps with fluid absorption if you drink while eating. To ensure proper hydration, drink regularly throughout the day, begin drinking small amounts of water (about 8 fl oz) at least 30 minutes before you begin training, then drink another 8 to 12 fl oz immediately before you begin your activity. During training, you should drink 6 to 12 fl oz of water or sports drink around every 15 minutes. Finally, drinking after exercise is a must to ensure you replace lost fluids.

The best way to treat dehydration is to prevent it from occurring. If you suspect excessive fluid loss during the race, take a rehydration solution, walk and contact one of our race doctors as soon as possible.

One of the most common health problems amongst extreme adventure competitors is heat exhaustion. When the body is unable to cool itself through sweating, serious heat illnesses may occur. Symptoms of heat exhaustion are:

• Intense build up of heat in head – causing severe headaches, dizziness or light headedness. In extreme cases the sufferer may faint.
• General confusion or inability to think straight
• Loss of muscle control and weakness of the body
• Extreme tiredness, upset stomach, vomiting
• Pale, clammy skin and excessive breathing


To help avoid heat exhaustion, it is recommended that you
• Drink plenty
• Wear light, breathable clothing
• Slow your pace to adjust to the heat
• Take frequent, short breaks to allow the body to cool down
• Avoid alcohol or beverages with caffeine. These make the body lose water and increase the risk for heat illnesses.

If you think you or another runner is suffering from a heat-related illness during the race, find a cool and shaded spot, lie down with your feet elevated and contact one of our doctors immediately. If heat exhaustion is left untreated, it could lead to heat stroke. Symptoms include nausea, dizziness, goose bumps, extreme fatigue, weakness, weak and rapid pulse, heavy sweating, uncoordinated stride or vomiting.

There can be a dramatic drop in temperature in the Namib Desert after the sun has gone down. This will leave you at risk of being exposed to the cold and could even leave you in danger of getting hypothermia.

Hypothermia occurs when the body loses heat faster than it can produce it and the core temperature of the body falls. It is surprisingly easy to progress from very cold to dangerously cold due to a combination of wind, wet clothing, fatigue and hunger, even if the air temperature is above freezing. Cold conditions are exacerbated by wind where the temperature is effectively lowered and it appears to be much colder than it actually is. This phenomenon is known as wind-chill.

Symptoms of hypothermia are:
• Exhaustion
• Numb skin (particularly toes and fingers)
• Uncontrollable shivering
• Slurred speech
• Irrational or violent behaviour
• Lethargy
• Stumbling
• Dizzy spells
• Muscle cramps

Managing mild hypothermia is relatively easy, as long as you have the correct protection from the environment. It is best to dress in layers; silk, wool and some of the new artificial fibres are all good insulating materials. A hat is important, as a lot of heat is lost through the head. A strong, waterproof outer layer is essential, as keeping dry is vital.

If you or another runner is suffering from hypothermia, you must prevent any further drop in body temperature. Seek shelter and wrap up to insulate yourself. Replace any wet clothing with dry ones; make sure your head, feet and hands are covered; drink warm drinks if possible and eat high energy foods (sweets, chocolate etc). Get into your sleeping bag – with another person if possible to help you warm up.

Namibia Ultra Marathon
Across the Divide

Desert Medicine Training Course – Namibia

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