Tour de France: how many calories will the winner burn?

the essential
Tour de France cyclists are able to generate huge amounts of energy over incredibly long periods of time compared to most people. An American scientist modeled the phenomenon for 20 years.

Imagine. The Tour is well underway this time in France and is approaching July 14th. You are at the beginning of stage 12, a mountain stage … Your first task will be to cover 33.2 km to the Galibier pass, in the French Alps, gaining about 1,305 m of elevation gain.

But this is only the first of the three great ascents of your day, with a total of approximately 3050 meters of altitude. Because then you will face the top of the Croix de Fer pass and finish the 165.1 km stage with the famous climb of the Alpe d’Huez with its 21 serpentines.

Even at my best, I might not be able to complete this twelfth step. Even less to do so in a time that would approach the five and a few hours it will take the winner to cross the finish line. And this twelfth stage is just one of 21 to be completed during the 24 days of the Tour.

I am a sports physicist and have been modeling the Tour de France for almost two decades using terrain data, such as the one given here for stage 12, and the laws of physics and physiology. But I still can’t fully understand the physical skills needed to complete the world’s most famous cycling race.

Only a small sports elite is able to complete a stage of the Tour de France in a time that is measured in hours, not days … The reason they are able to do what the rest of us can only dream of is that these athletes can produce large amounts. of power.

Power is the speed at which cyclists are able to burn energy, and the energy they burn comes from the food they eat. During the Tour de France, the winning cyclist will burn the equivalent of about 210 Big Macs (about 550 kcal).

Cycling, the “game of watts”

To advance a bicycle, a Tour de France runner (like any cyclist) transfers, through the bicycle, the energy of his muscles to the wheels that push the ground and propel it. The faster a runner is able to produce energy, the greater its power. This energy transfer rate is usually measured in watts.

Tour de France cyclists are able to generate huge amounts of energy over incredibly long periods of time compared to most people.

For about 20 minutes, a recreational cyclist in good physical condition can consistently produce 250-300 watts. Tour de France cyclists can produce more than 400 watts during the same period. These professionals are even able to reach 1,000 watts for short periods of time, on a steep rise, for example, about enough power to run a microwave oven.

But not all the energy a cyclist puts into his bike is transformed 100% into forward motion. There are losses: these athletes have to fight air resistance and friction losses between their wheels and the road. And if you have the help of gravity in the descents, you have to fight it in the sometimes exhausting climbs.

To power and rotate my model, I incorporate all the physics associated with rider power, as well as the effects of gravity, air resistance, and friction. With all of this, I estimate that a typical Tour de France winner would have to deliver an average of about 325 watts during the approximately 80 hours of racing. Remember that most recreational cyclists are happy when they manage to produce 300 watts for just 20 minutes!

Tour de France runners should eat three to four times more calories than recommended under normal conditions. Pietro Agliata / AFP

Turns food into miles

So where do these exceptional cyclists get all this energy from? The food, of course!

But their muscles, like ours and like any machine, cannot convert 100% of the energy of food into energy produced. Again, there is loss. Muscles can perform between 2% for activities such as swimming and 40% for the heart (which is also a muscle).

In my model, I use an average efficiency of 20%. Knowing this efficiency, as well as the energy production needed to win the Tour, I can estimate how much food the winning cyclist needs.

On average, the most successful cyclists on the Tour, able to complete all 21 stages in the fastest times, will burn about 120,000 calories during the race, or an average of about 6,000 calories per stage. But in some of the toughest mountain stages, like this year’s famous twelfth stage, the slide is close to 8,000 calories!

To compensate for these large energy losses, runners eat delicious delicacies such as jam rolls, energy bars and delicious “jellies” … so as not to waste energy chewing them.

Tadej Pogačar, who won the Tour de France 2021 and 2020, weighs only 66 kilos. In fact, what’s striking about their sharp silhouettes is that these cyclists don’t have too much fat to burn to generate energy. Without reservations, they must therefore provide energy (food) continuously to their body in order to be able to expend it almost immediately, at a rate that seems superhuman.

This year, looking at a stage of the Tour de France, look at the number of times cyclists eat; now you know the reason for all this snack.The conversation

John Eric Goff is Professor of Physics atLynchburg University
This article is republished from The Conversation under a Creative Commons license. Read the original article.

Leave a Comment