Warming up for Tour de France stages has gone from being a marginal gain to a default protocol for time trials and hard-start road stages. In the extremely high temperatures at this year's race, achieving the goals of a warm-up without overheating and compromising performance is a physiological and logistical challenge. We asked EF EducationEasyPost's performance coach and technical innovation strategist Jacob Tipper and Wahoo's cycling category director Tyler Harris how the WorldTour outfit overcomes this using sports science, the latest technology and old-fashioned tricks.(Image credit: Getty Images)The science behind warming upIn a blistering heat wave, 'warming up' sounds counterproductive, so why do Tour de France riders do this?Sports scientist Tipper says, "A warm-up has to tick a few boxes. The one a lot of people forget is mental preparation. Psychologically, you still need to get yourself ready for exercise."You also want to increase core body temperature to an extent and increase vasodilation, the widening of blood vessels. As you breathe harder and exhale more carbon dioxide, that triggers more blood flow."And then you want warmer muscles, which good studies show are better for muscle contraction than colder muscles, and neuromuscular activation. That's the ability of the muscles to contract properly. Riders will sometimes work with bands to activate their glutes, and some guys do a few rev-outs on the turbo."Finally, you want to activate your VO2 [oxygen uptake] kinetics, which is essentially how well you are switched on aerobically and how efficiently you can use energy. Like when you restart a ride with 'cafe legs', your threshold will be lower than usual if your aerobic engine isn't switched on."(Image credit: Getty Images)What riders are trying to avoid in warm ups"All these things have a fine line," adds Tipper. "You don't want to tire yourself out, empty glycogen stores, or cause a lot of muscle damage. "You don't want to burn the mental matches you need to save for when push comes to shove in the race."From a core temperature perspective, you don't want to get too warm [since this lowers VO2 max] because in the Tour de France it's been very hot and we don't have a really hard start."This contrasts the approach of some track cyclists, who might need to go all-out from the gun, and wear ice vests and heated trousers to make their leg muscles much warmer than their core. Ahead of a longer effort, Tipper says: "You may decide to compromise and start with lower core body temperature, so you don't feel as good off the line but stay cooler for longer.""You are always trying to balance these things with the type and importance of the event. At the team time trial in Barcelona we had crazy hot temperatures, so keeping the core as cool as possible, relatively speaking, was important, but in the first few turns you had to ride at 500 watts, so you still had to be warm. That's the compromise between these two objectives."(Image credit: Tom Wieckowski)How riders stay cool while warming upAs you've probably seen at stage starts and at the start of the team time trial in Barcelona at the Grand Depart, riders are wearing ice vests and chilled towels, eating slushies, and getting blasted by fans. NetcompanyIneos even dunked their forearms in cold water while waiting to start in Barcelona. Like other teams sponsored by Wahoo, EF EducationEasyPost warms up on Kickr V6 smart trainers in front of Kickr Headwind smart fans. Elite's Aria smart fan does the same job for teams supported by the Italian brand."The Kickr Headwind automatically adjusts airflow based on real-time sensor data," says Wahoo's Harris. "Users can pair up to five supported sensors including heart rate, power, and core body temperature, and Headwind dynamically increases or decreases cooling based on the athlete's effort. "For example, it can respond to a combination of power output and rising body temperature rather than simply running at a fixed speed. The result is a more personalised cooling experience that helps riders stay comfortable during and after their hardest efforts."However, Tipper says: "We are not looking at the Core sensor in the warm-up and trying to stay below a certain core body temperature because it does not react quickly and accurately enough. "If someone goes badly in a race, we might look into whether core body temperature goes too high in the warm-up, as research afterward. That is where we are at the moment in terms of our learnings and developing our understanding.""Using the Core sensor, you could create a warm-up that doesn't overcook you. If before the Zwift races when your core body temperature gets to 39C in the warm-up, you prematurely blow up, there are almost definitely things you can take from that, but that's not what we are doing with it right now."During warm-ups, riders will follow the nutritional plan laid out by the team, whether that involves caffeine, carbs or bicarb, for example, while avoiding getting depleted. "The warm-up shouldn't do any nutritional harm and should keep you topped up on whatever you're losing fluid, electrolytes, carbs, etc," says Tipper. (Image credit: Getty Images)Cooling down on and off the bikeRacers will also cool down post-stage depending on the demands of the day. "Not everyone has the fun opportunity to finish with a full-gas sprint on top of the Tourmalet," says Tipper. "Guys who have chilled in a group further back or in the grupetto have basically done a cool down on the road."I hate the phrase 'flushing the legs out' but the idea is to keep blood flowing post-stage."It seems at this year's race that teams have upgraded their post-race cooling, with some switching from ice-filled paddling pools to dedicated trucks, the idea being that prolonged exposure to frigid temperatures reduces inflammation and thereby speeding recovery. But the scientific jury is out as to whether ice baths (and inflammation-reducing antioxidants in the form of cherry juice, for example) are beneficial even at demanding stage races like the Tour."Decreasing inflammation could have a negative long-term effect and it's debated how harmful it can be during a race," says Tipper. "Inflammation is a main driver of repair and proper growth, so if you did these things after every session you'd be worse off."At the Tour it's a fine line between feeling that you could be improving and getting so beat up that it's better to have a bit less inflammation, so you can perform that bit better the next day rather than feeling crap."After the succession of gruelling mountain days in the final week, an ice bath could benefit a lot of riders in the short-term at least, if they use them properly."Jumping in a cold paddling pool for a minute isn't doing a fat lot physiologically," says Tipper. "It's a nice relief, but unless you're spending enough time in there, it's offering no more than a cold shower."