Cycling in the Heat

Cycling is a popular sport, especially during the summer months. Professional cyclists participating in events like the Tour de France brave extreme temperatures, but measures are now in place to protect them from heat-related issues. Unlike football, cycling creates wind, which helps in cooling the body. However, it is important to be cautious as high temperatures can have a significant impact on the body.

Heat Production during Cycling

When cycling, the body works to propel itself forward. Only about 20 percent of the energy generated is used to exert pressure on the pedals, while the remaining 80 percent is converted into heat. If this heat is not dissipated, the body temperature will continue to rise, leading to the malfunctioning of vital organs. Therefore, it is crucial to get rid of this excess heat.

Methods of Heat Dissipation

The body has three ways to cool down: conduction, radiation, and convection. Conduction occurs when the body comes in contact with a cold object, radiation is the release of heat similar to the sun, and convection involves transferring heat to flowing air or water. Sweating, where water evaporates from the body to the surrounding air, is the most effective method of heat dissipation.

The Challenge with Sweating

While sweating helps regulate body temperature, it also leads to a significant loss of fluid, which is essential for various bodily processes, including muscle contraction. In warm conditions, the body can lose up to two liters of fluid per hour during intensive exercise. Dehydration occurs when there is excessive fluid loss and inadequate fluid intake. Even a 2% loss in body weight through moisture can noticeably decrease performance, and a 5% loss can result in a deterioration of up to 30%. It is important to exercise caution, especially in the absence of wind, uphill climbs, and high humidity, as these conditions hinder sweat evaporation. Drinking plenty of fluids is crucial, but the body can only absorb a certain amount. If the loss exceeds the absorption, dehydration will still occur. Sports drinks can aid in increasing fluid absorption.

Choosing the Right Sports Drink

The classification of sports drinks is based on their osmolarity, which refers to the number of dissolved particles of sugars and salts. Hypotonic drinks have fewer dissolved particles than blood, making them similar to water. However, water passes through the gastrointestinal tract too quickly for proper absorption. Combining water with a gel can alter the ratio in the stomach. Isotonic sports drinks have the same osmolarity as blood, allowing for better absorption. Hypertonic sports drinks, on the other hand, contain more dissolved particles than blood, aiding in the absorption of sugars but slowing down fluid absorption. Hypertonic drinks are essential for replenishing sugar levels, while isotonic sports drinks are better for fluid absorption than water.

Recommended Fluid Intake

Under normal circumstances, the body can absorb 750 ml to 1 liter of fluid per hour. However, it is not beneficial to drink more than that. Instead, focus on consuming the right type of beverage. Sweating causes the loss of essential minerals, or electrolytes, such as sodium and potassium, which are crucial for proper muscle function. Mineral loss is often associated with muscle cramps. Therefore, in addition to carbohydrates, it is important to have a good hydration strategy that includes an isotonic sports drink with sufficient minerals, particularly in warm conditions.

Last Advice for Cycling in the Heat

Extra caution is required when cycling in high temperatures, high humidity, and without wind. Even with a well-planned hydration strategy, dehydration can still occur if fluid loss exceeds absorption. Symptoms such as nausea, dark urine color, headaches, and decreased performance may arise during long rides. Additionally, the heart rate increases at the same power level due to decreased blood volumes caused by fluid loss. Adjust the duration and intensity of your rides according to weather conditions and take these symptoms seriously.