PERHAPS the biggest myth about heat disorders is that they do not fell those who are fit.

The truth is that even the strongest can succumb to heat cramps, heat exhaustion and heatstroke because fitter people tend to drive themselves too hard and fail to realise when they are in danger, according to the Singapore Armed Forces (SAF) medical corps.

Heatstroke, the most severe form of heat-related injury, is potentially fatal.

When it strikes, body temperature shoots beyond 41 deg C. Normal body temperature is about 37 deg C.

A person affected by heatstroke has a high body temperature, but he may not perspire; often, he is confused and violent. Some people become drowsy and may fall into a coma.

Complications such as brain damage and blood disorders can occur.

The most common type of heat injury is heat exhaustion, marked by symptoms such as headaches, nausea and fainting. It can lead to heatstroke if unchecked.

The third - and mildest - form of heat injury is the heat cramp, a painful muscle contraction in the thigh or calf as a result of excessive loss of water and salts.

Another myth is that heat disorders do not occur in cool weather.

Statistics show that, ironically, heatstroke happens most often in the evening, around 6pm. The reason is that people who take precautions in hot weather turn complacent as it cools down at the end of the day.

A recent study by military doctors found heat-related injuries to be the most common reason for helicopter evacuations of trainees from the Pulau Tekong training area to hospital. Of the 30 evacuations between 2002 and last year, 17 of them or 57 per cent were victims of heat disorders.

Over the years, the number of such heat-injury evacuations has come down, signalling an improvement in the management of such injuries. There were no heat-injury evacuations last year, down from six in 2005 and four in 2006.

The military doctors who authored the study noted: 'Heat injuries are a persistent training concern in the SAF...Continued vigilance is required in maintaining a heat-injury-free training environment for our servicemen.'

This is an area that would have been looked into during the three-day halt on all physical training and endurance activities imposed following the two deaths this week.

Today is the last day of the time-out.

What it is and how to prevent it

HEATSTROKE is a condition marked especially by the cessation of sweating, extremely high body temperature and collapse as a result of prolonged exposure to high temperature.
When it happens, doctors call it a tragedy, because the condition can be prevented and treated if people know what to do when it hits.

To prevent it:

• Drink until you are not thirsty, and drink some more. On a hot day, one should drink at least 10 litres of water.
• Sleep at least seven hours the night before a strenuous exercise.
• Remove extra clothing.
• Report sick if you do not feel well.
• Refrain from training while on medical leave.

If heatstroke happens:

• Move the person into the shade immediately and remove his clothing.
• Resuscitate him if he has collapsed.
• Reduce his temperature by pouring water on his body, applying wet towels and fanning him.
• If he is conscious, give him water.