Heat Stroke: A Serious Threat to Trail/Ultra Runners

• Before reaching a state of heat stroke, affected individuals may experience symptoms such as fainting, profuse sweating, an elevated yet light pulse, or developing cramps. If left untreated, these symptoms could progress into heat stroke.
• Proper hydration, including electrolytes, is crucial for any run lasting more than 4 hours due to the significant water and electrolyte loss the body experiences, especially in hot climates.
• Heat stroke can impair coronary function, leading to toxin buildup, a widespread inflammatory response, and blood clots, particularly in the brain's smaller blood vessels. This can result in seizures and loss of consciousness, with death becoming a real risk if not promptly treated.

Heat stroke is a severe medical condition that can pose a life-threatening risk for trail and ultra runners, particularly in Thailand's hot and humid climate. Understanding its symptoms, causes, and prevention measures is essential for athletes to stay safe during long-distance running races.

Heat stroke is an acute central nervous condition caused by exposure to high temperatures, resulting in the body's core temperature rising above 40 degrees Celsius. During exercise, our bodies naturally heat up due to increased organ function, but this is usually regulated by circulating more blood to dissipate heat. Sweating also aids in cooling the body. However, on extremely hot days, when the outside temperature is similar to the skin's temperature, perspiration may not effectively cool down the body, making it harder to regulate core temperature.

Additionally, prolonged exposure to heat and high humidity levels can hamper the body's ability to cool itself, leading to an automatic response of blood vessels expanding to increase perspiration. This can result in reduced core fluid circulation to the heart, leading to heat syncope, fainting, and even loss of consciousness.

Heat stroke can cause dehydration and an electrolyte imbalance, leading to impaired muscle function, cramps, and sunstroke. If core body temperature is not promptly controlled, it can continue to rise, increasing the risk of rhabdomyolysis, where toxins are released into the bloodstream, affecting the kidneys and potentially leading to renal failure.
Moreover, heat stroke can impair coronary function, resulting in toxin accumulation, widespread inflammation, and blood clots, especially in the brain's small blood vessels. This can cause seizures, loss of consciousness, and multiple organ failures, which can be fatal if not treated immediately.

The main causes of heat stroke are exposure to heat, belonging to high-risk groups (e.g., infants, the elderly, those with underlying health conditions, or those unaccustomed to hot weather), and prolonged exposure to heat during activities like outdoor sports, biking, or running long-distance races.

Heat stroke is preceded by symptoms of heat exhaustion, such as feeling faint, profuse perspiration, a rapid yet light pulse, and cramping. Ignoring these symptoms can lead to more severe heat stroke symptoms, including headaches, confusion, nausea, lack of perspiration, red and warm skin, seizures, and loss of consciousness.

As soon as symptoms develop, affected runners should find a cool, well-ventilated space, loosen their clothing, and sip water slowly and regularly. Cooling damp cloths can be applied to the armpits and around the neck, while the runner lies down with elevated legs to improve circulation to the heart. If symptoms worsen, a doctor or race volunteer should be notified immediately.

If a runner is found unconscious, their core body temperature can be lowered by applying ice packs to the neck, legs, and underarms. Emergency assistance should be called to transfer the runner to a hospital promptly.

The body deals with exposure to heat or hot weather by increasing circulation to the blood vessels located near the skin, thus increasing the production of sweat, while the body also reduces the amount of sodium lost through sweating. The extent to which athletes can keep their bodies cool depends on a range of factors, including sweat production capabilities, clothing, and fitness level.

In the fields of sports and medicine, there is a range of warnings and recommendations for anyone exercising in the heat, especially during the hottest parts of the year:

• Assess your risk levels for heat stroke.
• Hydrate properly before, during, and after competing, which should be rehearsed during training to ensure you do not lose more than 3% of your body weight during exercise. Nevertheless, it is possible to overhydrate, which could lead to an electrolyte imbalance, as the body can only absorb around 1.2 liters of fluids per hour.
• Hydrate using fluids that are effective in compensating for fluids lost in exercise, such as milk, orange juice, or carbonated drinks.
• Increase sodium intake when training or competing in high temperatures, and attempt to take in 60g of carbohydrates per hour.
• Try to keep the body as cool as possible before and during competition, avoiding direct sunlight as much as possible.
• Wear good quality sunglasses to protect the eyes from the sun’s harmful UV rays.
• Apply sunscreen that does not interfere with the body’s ability to perspire.
• Wear light-colored, loose-fitting clothing that will enable the body to sweat and cool effectively.
• Check the weather forecast before running and think of the temperature prediction as a 10-degree Celsius range, from 5 degrees under to 5 degrees over the predicted temperature.
• Train in conditions that mirror those expected during the competition for 1-2 days before competing to ensure your body is adequately prepared.
• Stop running immediately if you experience any dangerous symptoms.

Sports drinks should contain the following ingredient ratios to be effective:

• 4–8% glucose or 4–8g per 100ml. If fructose is used, it should account for no more than 3% of the total drink.
• 30–70mg of sodium per 100ml.

An effective ratio of water to glucose and sodium will help the body absorb nutrients more quickly, which is the main reason why sports drinks are preferable to plain drinking water.

Additionally, the body is capable of absorbing approximately 60g of carbohydrates per hour of exercise, so a high-quality sports drink is useful whenever running for more than an hour at a time.

For runners planning on racing for more than 4 hours, a high-quality sports drink becomes essential due to the amount of fluid and electrolytes lost over time, especially in hot temperatures. This is because hydrating with excess amounts of water in isolation could reduce blood sodium levels. If more liquids are taken on than the amount which has been lost, it could cause water poisoning or dilutional hyponatremia, which can be fatal. Sadly, occurrences of this are relatively common in the long-distance running community, especially in the summertime of hot countries.

Despite relatively common news of the dangers posed to runners, the draw of stunning natural surroundings and exciting routes means there are now more applicants for trail and other endurance races than ever before. However, proper training and awareness of potential dangers are crucial to any preparations, as is preparing the body for the humid conditions that cause heat stroke. Doing so could help you avoid multiple organ failures and the possible loss of life that is sadly associated with this condition. 

While trail and ultra running offer stunning natural surroundings and thrilling routes, proper preparation, awareness of potential dangers, and adequate hydration are crucial to ensure athletes' safety and well-being. Understanding heat stroke and taking appropriate preventive measures can help avoid severe complications and potential fatalities associated with this condition.