Fitness and Exercise

How Not to Get Overheated

Source: Dr Vincent Lim Sui-leong , Singapore General Hospital

Heat injuries refer to a spectrum of medical conditions, which arise from failure of the body to properly regulate its heat level, resulting in overheating.

Why do I need to know about heat injuries?

Singapore is a hot and humid country; and vivacious youths who lead active lifestyles and engage in physically strenuous sports such as football, basketball and kayaking, and that means heat injuries are a real concern. Heat injuries can kill if it is not recognised and treated early. Most importantly, by observing a few simple measures and knowing your limits, it can be effectively and easily prevented.

Predisposing factors

A number of contributing factors increase your chances of suffering from heat injuries. Some of them are obvious, like high temperatures, while others are less so.

Below is a list of factors to be aware of when training and playing in the heat.

High Temperatures	When air temperature is higher than 30-32 degrees Celsius, heat is gained by the body through radiation.
High Humidity	Reduces sweat evaporation which leads to decrease in heat loss through sweating.
Sun exposure	In sunny weather, there is heat gain from solar radiation. There is less heat gain when the weather is cloudy, cool and breezy.
Excessive strenuous physical activities	Increase body’s heat gain as a result of repeated muscular contractions.
Poor physical fitness, lack of sleep, obesity	Lowers efficiency of cardiovascular and sweating responses to exercise, making you prone to heat injuries.
Coffee, tea, alcohol	These drinks actually increase the amount of water loss by increasing urination.
Certain medications	Certain medications may reduce sweating or increase urination. Read the product insert or check with your doctor if unsure.
Febrile illnesses	Alter the body’s normal temperature regulation processes.
Illnesses that cause vomiting and diarrhoea	Increase fluid losses.

Signs and symptoms

Heat cramps is the mildest form of heat injury. It occurs due to excessive loss of water and salt, caused by profuse sweating. Painful intermittent muscle cramps are experienced in the larger muscle groups (calves, thighs and abdomen).

Heat exhaustion is a severe form of heat injury, and is a sign that the cardiovascular system is unable to cope with the metabolic demands of contracting muscles. The casualty experiences weakness, exhaustion, headaches, dizziness and profuse sweating with elevated body temperature. This requires prompt treatment.

Heat stroke, the severest form of heat injury, represents failure of the body’s temperature regulating mechanism, as evident by the core body temperature rising above 41 degrees Celsius and decreased or absence of sweating (which is a very serious sign). The casualty appears confused and aggressive, and may even slip into a coma. This is a medical emergency! Without proper medical attention, the casualty can die within minutes.

Prevention

With heat injuries, prevention is more important than cure because if you leave it too late, you may never get a second chance.

Drink lots of fluids before, during and after training. Do not wait to become thirsty before you drink. Drink until your urine becomes dilute and clear.
Avoid caffeine, alcohol and carbonated drinks. Plain water is the best; however, a good sports drink will also help to replenish salts and minerals lost through sweating.
Wear loose-fitting clothes that allow for good air circulation, and does not restrict your movements.
Avoid the extreme heat in the middle of the day. Schedule your training and playing sessions to cooler times, such as early mornings and evenings.
Avoid sunburn at all costs. Huge amount of fluids are lost through burnt skin. If you have to be in the sun for prolonged periods, remember “slip, slop, slap”. Slip on a shirt, slop on some sunscreen, and slap on a hat.
Schedule plenty of rest time in cool, shaded areas, as part of your training and playing.
Do not be too ambitious in your training regime. Start slow and gradually step up to acclimatise to your current training and playing environment.
Do not engage in strenuous sports if you are currently having, or have recently recovered from fever, flu-like symptoms and gastroenteritis. Inform your PE teacher or events organiser.

Lastly, do not ignore the warning signs.

First-Aid Management: The 7Rs

Recognise symptoms	Recognise and report them early.
Rest casualty	Lie or sit casualty down in cool, shaded area with good air circulation.
Remove clothing	Loosen any clothing to assist in cooling, whenever possible.
Reduce temperature	Douse the casualty in cool water. Use fans and other devices to reduce body temperature.
Re-hydrate	If the casualty is conscious and alert, give him/her lots of fluids to drink. If unconscious, do not administer fluids by mouth as this may cause choking.
Resuscitate	Resuscitate unconscious casualty if you are trained in BCLS (Basic Cardiac Life Support). Protect the airway, support breathing and give intravenous fluids. Otherwise, rush to a hospital as soon as possible.
Rush to a hospital	Do not delay!