8 tips from the pros for staying cool when cycling in the heat

One of the most difficult challenges for Riders at the Tour de France to manage is heat

No matter how much preparation a team does for the Tour de France if the riders aren’t prepared for high temperatures it can end their race. Investing in heat management is an area that continues to grow with researchers and scientists looking at everything from nutrition and training to equipment and kit. In this extract from new book 'The Science of the Tour de France', author James Witts looks at how pro-teams are beating the heat and keeping their riders on track and on top for Paris.

“It was an incredibly hot day with temperatures in excess of 35°C. I thought my head was going to explode when I arrived at the base of the final climb.” The words of Team Sky’s Geraint Thomas after Richie Porte – who’d replaced Chris Froome as leader following the Brit’s withdrawal at the end of stage five – and his team had struggled on stage 13’s mountainous route to Chamrousse, effectively ending their hopes of winning the 2014 Tour de France. “I’d been drinking three bottles [of water and carbohydrate drink] every hour – around 1.5 litres – to keep myself hydrated and ride at threshold,” Thomas continued.

Stifling heat also suffocated many stages of the 2015 Tour. When the riders reached the Pyrenees, temperatures soared to nearly 40°C. Both Vincenzo Nibali and Alberto Contador complained of being “unable to breathe on the climbs”. On the 13th stage from Muret to Rodez, roadside temperature measured 61°C – the record stands at 63°C set in 2010. FDJ’s Thibaut Pinot, who finished third in 2014, suffered so badly on the 188km 11th stage from Pau to Vallée de Saint-Savin that he finished over 21 minutes behind stage winner Rafał Majka. “I’ve come to realise these last few days that as soon as it gets hot, I quickly lose energy,” said the 25-year-old.

It’s one thing riding in the heat – it’s another riding at maximum effort in the Tour de France while climbing over 3,000m in a stage after numerous days of racing beforehand. Some days can be comparable to riding in a sauna, leading to overheating, hyperthermia or even worse.

1. Stay hydrated

Cyril Lemoine of Cofidis collects water bottles from the team car for his fellow riders
Cyril Lemoine of Cofidis collects water bottles from the team car for his fellow riders

Gone are the days when teams would see water as extra weight: “The goal now is that riders don’t finish the stage in a dehydrated state and that means staying within 2 per cent of their starting body weight,” explains Judith Haudum, nutritionist at BMC Racing. “If we fail to achieve that aim, their performance will be impaired.”

So for a rider like America’s Tejay van Garderen, whose racing weight hovers around 70kg, that’d mean losing 1.4kg. Any more, the theory goes, will result in a catalogue of negative side effects: an increase in core temperature, reduced muscle contraction, insufficient carbohydrate absorption and poor decision-making through mental fatigue.

“Sweat and electrolyte losses are huge in a three-week stage race like the Tour. With all that going on you need to maintain blood volume,” adds sports scientist Andy Blow, an expert on the role sodium plays in the body during cycling. A typical adult has a blood volume of around five litres, but that figure’s partly dictated by the amount of water consumed.

At the Tour, riders can easily sweat a litre each hour and that needs to be replaced. If not, blood volume will drop below five litres, making the blood more viscous and harder to pump around the body. This reduced blood volume lowers the rider’s cardiac output (amount of blood pumped by the heart each minute). So if a rider’s heart pumps out 100 millilitres (ml) of blood each beat and their heart rate is 100bpm, their cardiac output is 10,000ml each minute.

When dehydrated, blood volume can drop markedly, so despite an increase in heart rate, cardiac output falls. As blood supplies oxygen to working muscles, clearly this is detrimental to performance.

2. Replace fluids

On a six-hour hot stage, depending on what the rider’s role or strategy is for the day, they can sweat up to 1.5 litres each hour. That adds up to nine litres over the course of the day, and as you’re looking to lose no more than 2 per cent body weight, the ideal is that the rider will drink at least 8.82 litres during the race (one litre = one kilogram).

On a six-hour hot stage, depending on what the rider’s role or strategy is for the day, they can sweat up to 1.5 litres each hour

As the Tour is a multi-stage race, hydration efforts begin the moment the rider wakes up.”We visit the toilet and observe urine colour every morning of the Tour without fail,” says Michael Rogers of Tinkoff Sport. “We have a colour chart to gauge how hydrated or dehydrated we are. If we’re dehydrated, one of the simplest methods to hydrate is to sip cordial until the stage begins.”

Team Sky are a touch more high-tech and use a device that monitors dehydration from a urine sample. In fact, Rogers’s idea stems from his days at Team Sky where they adhered to what they called ‘a positive hydration strategy’. Simplified, that meant giving riders drinks all of the time rather than waiting for them to ask.

Urine charts are a simple way to measure hydration but don’t come without their flaws. Rob Child, performance biochemist at Team Dimension Data, recalls the 2014 Vuelta, where temperatures tipped over 40°C in the shade. “That was a crazy hot race,” he says. “I always get feedback on the riders’ hydration levels but it wasn’t as simple as saying your urine is this colour so you’re dehydrated. Take B vitamins, for example. They’re heavily pigmented so a strong colour and give the riders’ wee an orange hue.”

Child explains that once he’s distinguished whether it’s the supplement or dehydration causing the darker wee, it’s all about the window between breakfast and the stage start – which is around two hours, so there’s still time to address dehydration issues. “As well as water, we might make them a couple of bespoke bottles on the bike (with added electrolytes, for instance) that could last a couple of hours, though perhaps more like 90 minutes in the heat.”

3. Don’t forget the sodium

The most vital electrolyte for the sweating riders is sodium, which helps to maintain blood plasma volume and transport water from the bloodstream to working muscles. If the rider’s drinks contained water with hardly any sodium, the body wouldn’t retain it and it’d just be leached out into their soggy chamois.

Sweat contains sodium so the more you sweat, the more sodium you lose. But replacing these sodium losses isn’t easy, as how much you sweat comes down to a number of different factors. “One aspect that can play a role here is where a rider grew up,” explains Haudum. “If you’re, say, Australian, you can probably cope better with the heat than someone born and raised in Norway. You’ve adapted to it from an early age. But that’s not the full story. Your body type will have an effect, too. Look at Cadel Evans. He was a rider who packed a lot of muscle mass, and if you have more muscle, that means you sweat more and lose more electrolytes. If you compared someone less muscular like Alberto, based on muscle mass I’d suspect that Cadel’s more of a concern with dehydration than Contador.”

Andy Blow, a former elite triathlete, became so obsessed with the role sodium plays in hydration that in 2011 he launched a company called H2Pro Hydrate. H2Pro prescribe electrolyte tablets based on your sweat rate. “In the past we’ve done sweat tests for Garmin riders, the idea being they’d implement individual hydration plans,” explains Blow, though he concedes individualised race nutrition has practicality issues. “It still makes sense, though – electrolyte composition in an individual can vary eight to tenfold person to person. Multiply that over 21 stages and you could find, if they haven’t the right strategy, the heavy sweaters could have a disadvantage.”

“Tour riders shouldn’t go the other way, though,” warns Blow. “We tested Daniel Lloyd a few years back when he was racing for the Cervélo TestTeam because he’d actually gained weight during a Grand Tour. Because the race was hot, the nutritionist gave the riders more salt than normal. Broadly speaking, that’s sensible advice, but Lloyd was a low sweater so retained electrolytes easily. The extra salt just retained more fluid, meaning extra weight.”

4. Be aware of the conditions

Stricken Spaniard Joseph Beloki (centre) broke several bones at the 2003 Tour due to melting tarmac
Stricken Spaniard Joseph Beloki (centre) broke several bones at the 2003 Tour due to melting tarmac

Black strips of tarmac absorb the heat from the sun easily and by the time the day’s stage starts, road surface can easily reach 50-80°C. In turn, the air directly above is heated up like a kettle, so when the temperature in the shade is 32-40°C, that could equate to 50°C or more for the cyclist.

When the temperature in the shade is 32-40°C, that could equate to 50°C or more for the cyclist

Sometimes, the Tour roads reach such extreme temperatures that the tarmac can become sticky, catching out unsuspecting riders as they descend at 50mph plus. In 2003, ONCE’s Joseba Beloki was in second place overall and descending from Col de la Rochette. The most diligent course recce wouldn’t have unearthed a patch of tarmac softened by the midday sun, which sent Beloki skidding, breaking his femur, elbow and wrist.

The organisers took notice and ever since 2003 now deploy water tankers before the peloton are due through, to spray sections of road that are susceptible to melting.

5. Wear the right kit

In 2014, Team Sky’s Chris Froome tweeted a picture of his and his team’s new skinsuit. “This skin suit takes #marginalgains to the next level” it read.

You can see why a mesh suit would improve cooling – greater airflow sweeping over the skin, promoting a higher level of evaporative cooling. “It certainly cools but it’s not great from a UV protection standpoint,’ explains Simon Huntsman, head of R&D at Rapha. “If the riders do choose to go with the mesh suit or top, they must lather up with loads of suncream.”

While the mesh suit grabbed the headlines, it’s their – and other manufacturers like Tinkoff Sport apparel supplier Sportful’s – use of so-called cooling fabrics that provides an extra, albeit thin, layer of protection. “‘When it’s hot, it’s all about heat management and keeping the rider comfortable,” says Huntsman. “Managing that heat effectively is always tricky in high summer but we use a number of different technology platforms to try and improve cooling.”

“The first one is the weight of the garments,” he continues. “Weight will affect comfort so we try and keep the tops as light as we can without compromising the integrity. We also look at the structure of the textiles because when the rider is moving, he’s created a dynamic environment.”

Enter wicking. This is the process where moisture is drawn away from the skin and, in this case, to the surface of the cycle top. Because water conducts heat more than 20 times quicker than air, if sweat is left to pool on the skin, your skin temperature rises, which would ultimately lead to a drop in performance.

In intense heat, no fabric can currently provide the ideal evaporative cooling system to wick and dry in an instant. But there are technologies out there that give it a damn good try. Team Sky use a performance polyester yarn called Coolmax, a cross-section of which resembles a big flower. The idea is that the greater the surface area, the more effective a garment is at moving moisture down the yarn and into the atmosphere.

You’d think colour choice would be a heat management imperative, too. Elementary physics states that black absorbs all wavelengths of light and converts them into heat, while a white object reflects all wavelengths of light so the light isn’t converted to heat and the temperature of the object doesn’t noticeably rise. That’s why you can clearly see Tour teams wearing lighter colours like Tinkoff (yellow), Katusha (white) and FDJ (equally white).

“Yes, one of the challenges of designing Sky’s kit is the colour, namely black,” says Huntsman. “There’s obviously a potential of absorbency. So that’s why we use a technology called Coldblack.” Coldblack is a textile finish developed by Swiss company Schoeller that reflects both visible and invisible rays of sunlight, showing up to a 5°C drop over non-treated black tops. “Ultimately that means less fatigue,” says Huntsman.

6. Reduce core temperature

In the build-up to the Beijing Olympics in 2008, sports scientists from national federations around the globe had one major issue to contend with: how to manage the intense heat and humidity. One of the most forward-thinking was the Australian Institute of Sport (AIS).

The team at the AIS recruited 12 top-level cyclists and began trialling new methods to reduce their core temperature. After much experimentation, they discovered that athletes drinking 700-1,000ml of an ice slushie made by Gatorade realised a drop of 0.5°C. After a 30-minute warm-up, that 0.5°C reduction remained.

The idea seemed to die a death… until the 2014 Tour de France. While Marcel Kittel and John Degenkolb warmed up for the time trial, slushing away in the background was a machine that looked mightily like a Slush Puppie machine. “It was a Slush Puppie machine,” says Teun van Erp, sports scientist at Giant- Alpecin. “I picked up and adapted the idea from AIS research because my studies showed it’s well worth using.”

Teun observed that the riders’ bodies could store heat for longer because of the reduced baseline temperature. While your body starts to close down when internal temperatures get up near 39.5°C, the cooler your core is to begin with, the more thermal legroom you have to ride hard. “We noticed a positive effect on performance of 3-8 per cent depending on the cooling, the person and the environment though we’d only really used Slush Puppie when over 25°C’, says van Erp. “It’s also more useful for shorter, more intense stages like time trials.”

Research has also shown that consuming an ice slushie after a stage can help recovery. That got Team Dimension Data’s performance biochemist Rob Child thinking. “Often the weather conditions will dictate what I serve up on the bus after a stage. I was in Portugal with the team and it was a particularly hot day, so I thought they might like some ice slushie. Then I thought how useful it would be to pack in some slow-releasing carbohydrates and protein, too. So I thought why not make some rice pudding, add a sprinkle of protein powder and stick it in the freezer. It lowered core, refuelled and repaired muscle all in one go. But, more importantly, they liked it.”

7. Stay cool

Peter Sagan cools down during the 161km 17th stage of the 2015 Tour
Peter Sagan cools down during the 161km 17th stage of the 2015 Tour

Another cooling innovation that Team Dimension Data, Giant-Alpecin and a number of teams have adopted from the Olympics is the ice vest. This concept stretches back to the 1996 Atlanta Games where Australian rowers stuffed ice packs into their vests during the warm-up. Now it’s unusual for a rider to be warming up on the turbo for a hot stage not to be wearing this cooling apparel.

“We only use them between 20-25°C,” says van Erp, “and they’re not as beneficial as ice drinks.” It’s a view echoed by Larrazabal at Trek. “Yes, we use them as they cool down the skin and create a nice feeling. However, they don’t really cool down the core so it’s more a sensory impact than a physiological one.”

That feeling of pleasure leads to another WorldTour confession: as soon as the mercury rises, Froome and co. love to press women’s tights against their flesh. “Like many teams, we use ice socks down the back of our necks,” says Rowe. “All you do is get a woman’s stocking, fill it with ice, cut it in sections and stick it down the back of your neck. They really help.” Michael Rogers agrees, rating it the number-one strategy out of all the ice-cooling practices employed by Tinkoff Sport.

In the case of Trek-Segafredo and Messrs Mollema and Cancellara, wristbands. “During a hot stage, we have one guy come back for the bottles and one for the wristbands,” says Josu Larrazabal, trainer at Trek-Segafredo. “They’re wristbands that are sprayed with ice liquid and kept in the cooling box. They then either put it over their hands or wrists for some cooling relief. When the guys pick up the bottles and bands, we also throw the liquid over their body, legs and head,” he adds. “It gives them a feeling of freshness.”

Many teams still offer the traditional ice bath – despite recent research suggesting its use may blunt muscular adaptation – though teams with healthier budgets may also employ the iCool system.

8. Acclimatise to the heat

Research has shown that healthy adults exposed to conditions that elevate their core temperature by 1°C to 2°C for 60-90 minutes over a period of four to ten days will afterwards elicit a lower resting core temperature, greater blood plasma volume and an increased sweating rate – all favourable adaptations to exercising in the heat. Tales of riders sitting in saunas to acclimatise stretch back to the early 20th century.

“You find that once the classics are over, heat acclimation kind of happens in a progressive way,” says Larrazabal. “Many of the guys at Trek live and train in Spain but they’ll also race California, the Dauphiné or Switzerland – all of which prepare them for the Tour.”

There’s also the thermal-management that derives from being incredibly fit. Similar to heat acclimation, as your fitness grows, you experience a host of adaptations that are naturally conducive to racing fast in the heat. These include an improved sweat response to dissipate heat quickly, which stems from both lower core temperature thresholds for the initiation of sweating and greater sensitivity of sweating response to increasing core temperature.

“Improved aerobic capacity also leads to elevated plasma volume and cardiac output,” says Brock University’s Stephen Cheung. “This minimises the competition for blood distribution between skeletal muscle and skin.” In short, as Sagan, Nibali and Valverde rack up the miles, their bodies develop a greater capacity for, and a slower rate of, heat storage.

James Witts’ The Science of the Tour de France is on sale now from Bloomsbury for £11.89. To buy a copy head here.

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