Cycling in hot weather


Cycling is a sport you especially practice in the summer time. In the Tour de France the pro cyclists get on their bikes every day even when the temperatures go through the roof, although there is now a heat protocol to protect the cyclists. Unlike football, riding a bike creates wind that provides the necessary cooling. Of course you sweat a lot and you have to drink more, but otherwise it’s doable. Yet you must be careful at high temperatures. The impact on your body should not be underestimated.


Once on the bike, the body has to do work to move forward. Only a small part of the energy in this process can be used to put pressure on the pedals, about 20 percent. The remaining 80 percent is not lost but is converted into heat. If the body would do nothing with this produced heat, the body temperature would continue to rise and vital organs would no longer be able to function. This heat must therefore be got rid of.


Fortunately, your body can cool down. This can technically be done in three ways, namely conduction, radiation and convection. Conduction is by touching a cold object, radiation is simply like the release of heat as the sun does, and convection is heat given off to flowing air or water. Sweating where you evaporate water to flowing air falls into the latter category and is by far the most effective in getting rid of your heat.


The only side effect of sweating is that the body loses an enormous amount of fluid that is essential to keep other processes, such as muscle contraction, going. With too much fluid loss and too little fluid intake, dehydration is the result. In warm conditions and intensive exercise, the body can even lose two liters of fluid per hour. When you lose 2% of body weight in moisture, performance decreases noticeably and at 5% performance can even deteriorate by 30%. In the absence of wind, for example uphill and in high humidity, which makes it difficult for sweat to evaporate, extra caution is needed. The trick, therefore, is to keep drinking a lot. However, your body can only absorb a certain amount of fluid and if the loss is still greater than the absorption, the body will always dehydrate. Nevertheless, there are ways to increase the absorption, for example by drinking sports drinks.


The distinction in the type of sports drink is made mainly on the basis of osmolarity, or the number of dissolved particles of sugars and salts.  A drink is hypotonic if it contains fewer dissolved particles than the blood, this is the case with water. The problem with water is that the lack of dissolved particles causes it to pass too quickly through the gastrointestinal tract and therefore cannot be absorbed properly. But if you take a gel with water, the ratio in your stomach is of course different. An isotonic sports drink has the same osmolarity as the blood. The fluid is absorbed much better than with water, because it passes through the body slower. An energy drink or hypertonic sports drink, on the other hand, contains more dissolved particles than the blood. This allows the body to easily absorb sugars, but the fluid is again not absorbed as quickly. Hypertonic drinks are therefore essential to replenish the supply of sugars, while an isotonic sports drink stimulates the absorption of fluids much better than water.


Under normal circumstances, your body absorbs no more than 750 ml to 1 liter of fluid per hour. However, you can lose more per hour, but drinking more than that makes little sense. What does make sense is to drink the right beverage. This is because by sweating you lose a lot of minerals or with another word called electrolytes. These minerals, such as sodium and potassium, are essential for proper muscle function. The loss of minerals is even considered one of the causes of muscle cramps. So, especially in warm conditions, in addition to supplementing your carbohydrates, you need to make sure you have a good strategy with an isotonic sport drink with sufficient minerals.


So especially with high temperatures, high humidity and the absence of riding wind, extra care is needed. Even with a good hydration strategy, dehydration can be lurking, as the loss can be greater than the absorption capacity. Then, when the ride is long enough, symptoms such as nausea, a dark color of urine, headaches, and loss of performance can occur. In addition, the heart rate increases at the same power level because the loss of fluid also decreases the blood volume. In order to pump the same amount of blood to the organs and muscles, the heart rate must be increased. This is called heart rate decoupling in exercise physiology. Take these symptoms seriously and adjust the duration and intensity to the weather conditions!
If you want to know more about what services we offer for cyclists, take a look at this page. Or if you are considering working with a coach, you can find more information here. We also have an app, called JOIN, that creates a personalized and flexible training schedule for you and above all, the first 2 weeks are completely free!