Heat Related Illness in Sport

The Ironman World Championship in Kona, Hawaii consistently highlights the significant impact of heat and humidity on human performance. Despite being prepared with your hydration and cooling methods, ALL athletes are at risk for a heat-related illness. As an athlete, it's critical to understand thermoregulation, the impact of heat on the body during exercise, heat related symptoms, risk factors, what to do if you suffer from it and how to reduce your risk. Stay smart, stay hydrated, stay cool and stay aware. Your health depends on it.

Thermoregulation

Thermoregulation is the maintenance of internal core body temperature by balancing heat generation with heat loss. 98.6 F (37 C) is the accepted norm for human body temperature. Hyperthermia occurs when your body absorbs or generates more heat than it can release. Your body is always adjusting to keep your body in homeostasis. Muscle contractions product heat as a by-product of metabolic processes. Because the body is very inefficient during exercise, ~75% of energy is released as heat (in other words, much of the energy used to fuel muscle contractions is lost as heat). 

When you get too hot, your body needs to cool itself down by offloading some of the heat into the environment. Heat can be lost through the processes of conduction, convection, radiation and evaporation. Evaporation is the primary method of cooling the body during exercise. The evaporation of sweat is the body’s natural air conditioner. To change from a liquid to a gas vapor, the water molecules break and the energy used to break those bonds is taken from the body in the form of heat. When relative humidity is high, the air is close to saturation and holds a significant amount of water vapor. As a result, there is less room in the air for more water molecules to change from liquid to gas, so evaporation slows down. This makes the body's natural cooling system less effective. This leads to sweat pooling on the skin (feeling sticky), causing you to feel hotter, even though you are sweating more.

If the body is generating more heat than it can release - often due to effort, hot and humid conditions, dehydration or other risk factors - it can lead to serious health issues, such as heat exhaustion, heat stroke or death.

 

Body temperature and hydration - racing in the heat

Tomorrow is the 2024 Men's Ironman World Championship in Kailua-Kona, Hawaii. The females showed us great resiliency, strength and courage on/by the mountains of Nice, France and tomorrow the men will battle it out on an island.

The heat and humidity in Kona is something that you have to feel to understand.

The human body can do incredible things - like race for 140.6 miles - but it thrives within a limited range of body temperatures. Muscle contractions keep the body moving but a substantial amount of energy is converted into heat. As a result, the body generates a large amount of heat which significantly raises the body temperature.

To help keep the body temperature somewhat stable and to prevent overheating, the body must dissipate heat through sweating, increased blood flow to the skin and increased respiration.

For the body to do what it needs to do to help you maintain a stable core temperature, you have a responsibility to keep your body hydrated. And hydration doesn't mean taking in copious amounts of salt or drinking large quantities of plain water.

A well-formulated sport drink provides a practical (and easy way) to obtain fluids, electrolytes and carbohydrates, in the right formulation to optimize digestion and absorption. Because you will always need to consume water when you exercise for prolonged periods in the heat, a sport drink (with salt and carbs) is the most practical source to meet your fluid, sodium and carbohydrate needs.