As heat waves bake parts of Southern Europe, riders are contending with temperatures above 100F. That makes cooling vests a necessity.
(Bloomberg) — On extremely hot days with sweat clinging to your skin, merely existing can feel like an endurance sport. And yet, as large parts of Southern Europe endure temperatures above 100F (38C), the roughly 165 remaining cyclists in this year’s Tour de France must do more than survive: They have to dominate in a sport where winning often means covering 100-plus mountainous miles in as little as four hours. To have any hope of winning — without succumbing to heat exhaustion — many of them turn to wearable ice.
Since this year’s race kicked off on July 1, most riders have been seen wearing vests packed with ice. A Tour de France staple, the vests are particularly necessary this year, as record heat waves bake Europe and make strenuous outdoor activity dangerous. In addition to staving off the impacts of high temperatures, the vests can keep a rider’s core cool while they warm up their legs before a race.
Ice is the original cooling innovation: A century and a half ago, cutters would remove 1-ton chunks of it from frozen New England lakes and send them to destinations as far away as India. In competitive sports, cooling vests entered the world stage at the 1996 Summer Olympics in Atlanta, also marked by a heat wave.
Whether you’re an aspiring Tour de France winner or just a person jogging in July, staying cool is critical. Our bodies generate a lot of heat when we exercise, and only have so many tricks for keeping core temperature steady. Those include sending warm blood to the skin’s surface, where ambient temperatures can help cool it, and sweating, which cools us off through evaporation.
When it’s extremely hot outside and “athletes perform endurance exercise, for example cycling, the body reaches its physiological limits at the cardiovascular level,” says Douzi Wafa, a lecturer in the department of physiology at the University of Poitiers in France. “Our core temperature increases, which might provoke premature fatigue and negatively affect performance. It can even induce heat illnesses like heat stroke.”
Wafa is co-author on several studies that look at the effect of cooling the body during exercise. She found that during anaerobic exercise — like a sprint or a cycling time trial — it’s better to cool down before the activity. But for endurance activities, like long-distance cycling, it’s better to cool down during the activity.
Since ice vests can be cumbersome during the race itself, Tour de France cyclists also employ other hacks to keep cool, including a steady stream of cold beverages, standalone sleeves filled with a frozen gel-like material, splashing cold water on wrists and even pressing ice-filled pantyhose against their necks.
“We use ice packs wrapped around the neck because there are a lot of cold receptors there,” Wafa says. Cold receptors are specialized nerve sensors responsible for letting us know when something is chilly. Because the neck has a lot of blood vessels close to the surface, warm blood also cools off as it passes by the icy stocking.
This is far from the first Tour de France playing out in uncomfortably high temperatures. Last summer was Europe’s hottest on record, killing an estimated 61,000 people, including 6,400 in France, according to a recent study in the journal Nature Communications. And heat isn’t only a threat to riders’ bodies: In 2003, cyclist Joseba Beloki famously crashed after his bike hit a patch of tarmac melted by high temperatures. He broke his femur, wrist and elbow. Reporters on the scene could see where the tar had been shredded by Beloki’s impact. A heat wave across Europe killed 70,000 people that summer, more than 15,000 of them in France.
Europe is the world’s fastest-warming inhabited continent, which makes this summer’s heat wave more of a harbinger than an anomaly. A separate study in Nature Communications last year dubbed the region a “heatwave hotspot” because of climate change-induced shifts in the atmosphere. That raises questions around how long the Tour de France can continue, at least in July.
Read More: Air-Conditioned Clothing Is One Way to Beat the Heat
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