By: Ng Jing Yng

The popularity of endurance events here is evident, with some 3,600 participants taking part in this year's Osim Singapore International triathlon.

In a triathlon race, conditions can be challenging - completing a 3.8km swim in the open sea, 180km of biking and a full 42km marathon run one after another.

These competitions are not without risks, especially when in the heat of competition, one might fail to notice the warning signs that the body is giving, doctors said.

Dr Jason Chia, consultant sports physician at the Singapore Sports Medicine Centre, said the causes of sudden cardiac death from exertion for those under 35 years of age are typically from underlying congenital heart problems or heart problems that emerged earlier.

For those above 35 years old, it could be due to underlying coronary artery disease. However, for both age groups, there could be an overlap of causes.

Dr Patrick Goh, consultant sports physician at SportsMed Central, said there are measures that can be taken to prevent mishaps during a race.

Before starting a strenuous exercise regimen or stepping up training, athletes should go for a health screening to assess his ability and health condition.

Dr Goh also advised athletes to train according to their level of fitness and match the training programme to race-like conditions to acclimatise the body.

During the race, watch out for these warning signs:

Chest pain

This is a sharp, gripping pain in the area behind the breast bone, lasting for short durations of about four minutes, said

Dr Ben Tan, chairman of the Sports Safety Committee.

The cause is angina - chest pain caused by ischemia, a restriction of blood supply. Angina is common during physical activity when the heart rate and blood pressure increase due to the heart's demand for more oxygen. Angina occurs when the demand for oxygen exceeds the oxygen delivered.

The pain will sometimes radiate up to the neck, shoulders and back and is often associated with sweating.

The athlete must discontinue the race immediately and seek medical help.

Dizziness

In physically taxing events like endurance races, a participant should take note if he feels weak and giddy, said Dr Teh Kong Chuan, senior consultant in sports medicine at Alexandra Hospital.

The cause might be lack of blood or oxygen going to the brain and he may even feel dizzy. While this may not be life-threatening, it is still advisable to take a break and seek help until he feels better.

Palpitations, irregular heartbeat

Palpitations occur when the heart seems to be pounding or racing and they must not be ignored, said Dr Tan.

The normal resting adult heart beats regularly at an average rate of 50 to 100 times per minute.

'When you exercise, the heart will be beating faster, but it has to be regular,' he said, adding that irregularity is never a good sign and the athlete must seek help.

Irregular heartbeat, also known as arrythmia, is an abnormal rhythm or rate of heartbeat. Even if the rhythm remains regular, it can occur along with rapid or slow heartbeat.

High body temperature

During races, athletes may experience a heat stroke that can be fatal if not treated immediately, said Dr Teh.

One of its causes is dehydration and symptoms include fatigue, dizziness and disorientation.

The body generates heat due to metabolism and usually releases it through perspiration. But under extreme heat along with physical exertion, the body may not be able to quickly dissipate the heat.

If the person is dehydrated, less sweat will be produced and the body temperature will rise rapidly.

He must be taken to a shady area for rest and drink fluids to hydrate himself. Medical help must be given.

This article was first published in Mind Your Body, The Straits Times.