- Heat stress during exercise can affect anyone, regardless of age, fitness level, or body type.
- Exercise causes body fluid losses from moisture in exhaled air as well as from sweating. This causes a thickening of the blood, and places a strain on the cardiovascular system (heart and lungs) as the heart rate increases in order to maintain adequate blood flow to the exercising muscles and vital organs. Blood flow to the skin is reduced, and sweating then decreases which causes the body core temperature to rise.
- Heat illness progresses through a series of stages. Initially, athletes experience painful “heat cramps” usually as a consequence of dehydration.
- These can be treated by escaping from the hot environment and ingesting a sports drink.
- If heat exhaustion occurs, the athlete may cease to sweat. This leads to a rapid increase in core temperature, and will result in headache, nausea, dehydration, chills, dizziness, and in some cases, a loss of consciousness.
- Heat stroke is much more serious. Symptoms include a lack of sweat, headache, rapid pulse, altered mental state, confusion, lethargy, seizures, and even unconsciousness and a body temperature over 101°F / 38°C
- If the body temperature is not lowered quickly, heat stroke can be fatal. If you suspect someone is suffering from heat stroke, seek medical help and take immediate action to start lowering the body temperature. While you wait for an ambulance, help the person into the shade or to a cool place, wet their body or wrap them in a wet sheet to increase evaporation, and provide water.
Tips to Prevent Heat Stress
- Gradually work your way up to several hours of exercise in the heat during the first few training sessions
- To ensure that you are properly hydrated, weigh yourself before and after hard training sessions in the heat. If you finish a training session with a weight loss of more than 3 to 4 %, you should practice drinking more while on the bike.
- Wear a white or light-coloured jersey to reflect radiant heat as much as possible. Wear clothing made from “technical” materials that wick perspiration away from your body, and breathe very well.
- Do not use oil-based sunscreens as it impedes sweating.
- When cycling, the wind moving across your body can remove body heat that is produced. Fluid replacement is more easily done during the cycle so take advantage of the opportunity.
