Weight is one of the most decisive factors in cycling. Especially in professional cycling, the urge to lose weight seems to have spread quite a bit. Especially in the grand tours it is the flyweights that are calling the shots. The era that a very big Dane or Spaniard won the Tour seems to be light years behind us. Yet an extremely low weight also seems to have its downsides. This article discusses the meaning and nonsense of a low weight.
ON THE FLAT
The body of a professional cyclist consists of approximately 10 percent fat, 15 percent bone and 50 percent muscle mass. This means that a cyclist weighing 70 kilos will soon be measuring 7 kilos of fat anyway. On the flat, this is usually not such a problem because air resistance is the biggest factor to overcome. A kilo more or less has a small effect on the frontal surface. For comparison, a cyclist riding alone at a speed of 42 km/h in a windless environment will have to overcome about 87% air resistance, 10% rolling resistance and about 3% loss in the transmission of the rotating parts. For this he will have to deliver a total of 350 Watt in this example. The weight does have an influence on rolling resistance, but with two kilos less and the small percentage of only 10 percent on the total resistance it will only save about 0.5 watts. So this doesn’t really seem worth the effort. Although of course in professional sport it is settled with this kind of small differences. On top of that, acceleration such as demarrage and sprints mass plays a more important role, but that is beyond the scope of this article.
IN THE MOUNTAINS
If we go into the mountains, the impact of 2 kilos is even greater. At a gradient of 9%, our 70 kilo cyclist cycles uphill with 350 Watts at about 16 km/h. Now, however, the aerodynamic resistance is only 5% and the resulting gradient resistance is no less than 88% of the total resistance to be overcome. With two kilos less body weight in this example 10 Watt less power is needed for the same speed, or the other way around, with the same power, the two kilos lighter cyclist goes 0.5 km/h faster.
On the basis of this theoretical explanation, it therefore seems rather obvious that trainers, teams and cyclists strive for as low a weight as possible. For the gc contenders in grand tours this means a fat percentage of between 5% and 8%. However, this is not the percentage of fat that they use all year round on their bikes, but a very cunning way of working towards it.
In order to achieve such low fat percentages, a strict diet tailored to the training load is indispensable. You will eventually have to train with a negative energy balance in order to lose weight. This simply means that the intake of kilocalories must be less than the consumption. On an average training day, a professional cyclist burns about 3000 kilocalories. In addition, fuel is still needed for the normal metabolism, which means that 4200 kilocalories are needed daily to prevent shortages. To create a deficiency in which the body can still optimally recover from the effort is a very complicated puzzle. Incidentally, recent research has shown that the rest/base metabolism in frequent athletes is lower than in less active people. This is probably caused by the fact that a person prefers to be less active after heavy exertion. Cyclists are therefore expected to lie on the couch as much as possible after training.
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What about KETONES
If we go back to two kilos of weight loss, it is essential to create deficits so that stored fat tissue is converted into energy. The process in which your body enters a state in which the body fat is converted into energy is called ketosis. In this process, stored fat tissue is converted into ketones (indeed those infamous ketones) and used as energy for the cells. Ketones are therefore nothing more than a natural extra source of energy. The conversion of fat tissue into ketones does not happen when there are enough carbohydrates nearby to convert into energy. That’s why you literally have to starve yourself to encourage the body to use stored fat as energy. Training with a low carbohydrate supply, sober training, for example, is a method to achieve this. However, this is not without danger.
The great danger lies in the fact that your energy systems are never really neatly separated, but are always mixed up. For example, the body always burns a little protein, but as long as the intensity is low enough or there are enough carbohydrates present, you will only burn a little protein. These proteins are essential for muscle building. When the carbohydrates are almost depleted and your body starts to burn stored fat tissue, you will also use more proteins as energy. This not only reduces weight, but will also cause loss of strength because muscle tissue is not regenerated properly. The puzzle in training physiology nowadays is to lose weight by training with a negative energy balance, but without a loss in power.
The problem of a REDUCED IMMUNE SYSTEM
An extremely low fat percentage also has its drawbacks. In the first place it is mentally extremely heavy to be stuck to a very strict training and nutrition regime over a long period of time. This also explains the weight fluctuations of the tour favorites. In addition, hormone functions can deteriorate with reduced production of estrogen in women and testosterone in men. Because of these reduced hormone functions, osteoporosis (osteoporosis) is also lurking. This causes faster fractures in the event of a fall. The functioning of the immune system also decreases, as a result of which a person becomes ill more quickly. Top form and getting sick are therefore very close to each other in top sport. Of course, this can also completely negate the entire performance improvement. Trying to lose weight and improve performance without the right guidance is not nearly as easy as it seems.
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