Yon the final minutes before the hottest stages of the Tour de France, the man in the yellow jersey, Jonas Vingegaard, can be seen wearing a cryovest, an attractive ice vest. Keeping his body temperature down delays the inevitable spike, at least a bit, and as soon as he finishes the run, he cools off in front of an industrial-sized fan while a staff member drenches his neck with ice-cold water. .
The south of France has been terribly hot in recent days. Temperatures reached 39°C and a weather warning was issued in regions including Alpes-de-Haute-Provence, where the Tour is in its third week of tough racing. The road surface, a few inches below the cyclists’ feet, is a scorching 60°C, cooking the cyclists like a pizza oven. Cyclists may be anatomical abnormalities, but they race at their limits and the inescapable heat can break them.
Inside the peloton, ice cubes are piled on helmets and specially designed jerseys and socks are stuffed. Chilled drums are pushed down and wet towels are wrapped around the shoulders. Britain’s Tom Pidcock wears his own cooling jacket made up of 20 individual pockets. Along the way, they meander to the side sheltered by trees or some tent awnings, and then team doctors assess their weight loss, as well as their urine.
The area for marginal gains has shifted in phase over the years: the focus was body fat percentage, diet and nutrition, sleep (Team Sky would bring a rider’s custom bedding to every new hotel); key data points such as functional threshold power and Vo2 max; improvements in aerodynamics and altitude training. They are still relevant but, increasingly, heat adaptation is becoming a critical tool in a cyclist’s arsenal.
Vingegaard’s closest rival, Slovenian Tadej Pogacar, has a reputation for battling the heat, while oddly enough, Vingegaard, who grew up in Denmark’s much flatter relief and cooler climate, thrives on hot and sticky days. in the high mountains. Pogacar went to special measures this year, training in Spain’s Sierra Nevada desert, where he wore extra layers of clothing to stress his body and deliberately limited nutrition and water intake to replicate the exhaustion of a hot day.
Getting enough energy on board before and during the day’s race is vital. Elite cyclists train to eat as much food as possible, literally stretching their stomachs, in another secret discipline within the sport. When they can’t take on more, it can be expensive. “I need to assess a bit, but I think I just didn’t have enough energy,” said Ineos’ Tom Pidcock after missing valuable time on hilly stage 14 due to heat exhaustion. “Yesterday was a late stage, late dinner and I really couldn’t eat enough.”
Sodium replenishment has become an industry unto itself. One company, Precision Fuel and Hydration, works with the Belgian team Lotto-Dstny to devise personalized fueling strategies, based on each cyclist’s perspiration rate and sodium loss per liter of sweat. Beads of sweat are drawn from a contraption on the arm and carefully analyzed: everyone sweats differently (it has nothing to do with fitness or aerobic capacity) and therefore everyone’s energy needs are unique.
It all fuels the body’s ability to respond to a rising core temperature. I recently put this to the test at the Porsche Human Performance Center in Silverstone, riding a Watt bike for 30 minutes in a 40C heat chamber, to get a minimal idea of what a Tour de France cyclist might experience. Even in that short amount of time, with a manageable cadence, the heat was sweltering and the legs felt noticeably exhausted.
My core temperature was measured throughout the experiment to ensure it did not exceed 40°C, at which point the test would have been abandoned. Below 38°C, the body can function at high efficiency, but once the rider’s temperature rises above 39°C, the brain tells the muscles to slow down and fatigue sets in. Above 40°C, heat exhaustion (losing too much water and sodium through sweat) is at play. ; above 41C there is a serious risk of heat stroke (when temperature regulation fails) and the body shutting down.
My temperature got very close to 40°C before stabilizing at 39°C. Getting off the bike and out of the chamber half an hour later brought me a rush of relief.
Touring riders have an arsenal of tools to prepare for such extreme conditions, but ultimately they can only do so much once they hit the road. There they are exposed and have no choice but to ride in the heat. There’s a balance to be struck between conserving production and pushing hard: the quicker they finish, the quicker it’s over.
On the other hand, for Vingegaard, the tougher the race and the harsher the conditions, the better chance he has of winning another yellow jersey. After two and a half weeks of grueling racing, from the broad coastline of the Spanish Basque Country to the high alpine roads, in torrential rain and sweltering sun, it’s almost there.