The Heat Takes Its Toll

It’s been infernally hot on the Tour de France with the temperature in the shade reaching 39°C (102°F). Only the riders can’t sit in the shade they must race in the open. Reports said riders drank up to 20 bottles each during yesterday’s stage.

Thirst and heatstroke are obvious factors but the heat takes its toll in many ways.

Hot air: When we talk of heat it commonly means the air temperature cited in forecasts. This is the shade temperature and on the open road the temperature is often much higher. The black tarmac soaks up the heat and can be 60-80°C, enough to cook an egg. So on a day without a breeze the air above it gets heated by convection to 40-50°C. But this is only the start of the problems.

Radiation: if the road heats the air it also radiates back the heat. The same on a climb cut into the site of a mountain where the rock face on one side of the road radiates heat back. The amount depends on the exposure to the sun, the type of rock (or concrete) and other factors but it’s noticeable. There’s also the direct effect of the sun too as it beats down on riders. When pedalling there’s a draft meaning this isn’t so obvious but it’s there. Sunburn is a concern, there’s the long term worry about skin cancer but short term reddened skin means precious blood is being diverted from the muscles to the damaged dermis.

What to do? Ride. The air flow from riding is cooling than standing still but this is because you sweat. Sweat is an essential body function but not without its problems. All that water has to be replaced and riders were consuming 15-20 bottles each yesterday. The easy part is squirting it into your mouth, getting it through the intestines into the rest of the body can be fatiguing. The drink needs to be right too, riders will take bottles of water to drink and spray themselves and bottles with energy drinks containing salts to replace the minerals sweated out. Often there’s a small “x” written on the bottle to mark the difference so nobody sprays themselves with a sticky sugary drink.

Someone has to go and fetch all this water. This year Michał Kwiatkowski has been a star water carrier. Dropping back to the team cars is never as easy as it looks, there’s the added distance of going back and forth between the peloton. The effort is hard, it can look easy riding back to the peloton but take yesterday’s stage when Giant-Alpecin were doing through and off, a rider trying to get back to the bunch must work harder than the bunch and with less aerodynamic assistance, all while carrying several bottles. So simply getting the water is tiring. For the breakaway the Tour has a special moto fraicheur with a rank of bottles for the riders to collect if they can’t get a team car and on a hot day the rule about not being able to get food and drink from team staff in the first and last 20km is relaxed. If all else fails out comes the can of Coca Cola.

Returning to sweating, it involves losing a lot of water but also minerals. Sometimes you can see the salt marks on jerseys and the straps of helmets. There are tests to measure who sweats what as it varies, you could be a big potassium loser and someone else runs out of sodium fast. There’s also the pain from the salt going into open wounds, not severe but it just adds to the discomfort. Sweating into the pad of your shorts can make them uncomfortable and saddle sores can develop too.

Water is also lost from the lungs. You might see your breath condensate on a cold winter’s day but that’s because the cooler air makes it visible. Every breath sees you expire water and breathe hard for exercise and you lose more. The amount isn’t huge but estimates say 75ml an hour is possible, so over a stage that’s another bidon gone.

Body type makes a difference. Evolutionary theorists think one reason for our development was learning to walk upright. The theory goes on a hot day on the plains of Africa an upright human presents less surface area to the sun compared to, say, a crawling chimp and so an advantage for hunting and foraging on a hot day. Back to cycling and having a large surface area can help with cooling. The twiggy build of Chris Froome or Robert Gesink can be advantageous compared to the bulk of André Greipel or John Degenkolb.

Adaptation helps. BMC Racing saw the forecast for Utrecht and a heatwave and so had Rohan Dennis train during the hottest times of the day. After crashing out of the 2011 Tour de France Bradley Wiggins rigged an indoor trainer in a shed and used heaters to recreate the warmth of Spain rather than the chill of England before the 2011 Vuelta. For more on adaptation, try the BJSM podcast on the subject of heat illness.

Some teams use ice vests, waistcoats lined with pockets containing a gel that has been in the freezer. These have been used for “warm-ups” prior to the race, the idea being that the rider spins the legs on a trainer but the vests are used to keep the upper body at a more acceptable temperature. They’re also used for the post-race cool downs too, you can see Robert Gesink sporting one above. There are ice baths and and even cryotechnology. Once thought to help swollen muscles, the literature is inconclusive but The effect on core body temperature is proven and riders reporting they feel cooler and even sleep better for it.

UCI Protocol: new for 2015 is the UCI’s Extreme Weather Protocol which is meant to think of rider welfare when the weather is hard. But there’s not much to it, there’s no “wet bulb” limit like they use in marathons, just a pledge to hold a meeting if the weather is unusually hot or cold.

Summary

Forecast temperatures of 35°C sound hot enough but it’s way hotter out on the road. The tarmac can be burning hot and radiates it back to the riders to make for an infernal workplace. All this before stuffy hotels and apparently the aircon broke on Bretagne-Séché’s team bus.

Riding and sweating means you can still race when the air temperature exceeds body temperature but it’s hard with intensity and duration. This puts a strain on the body and it’s not easy to ensure the right balance of water and electrolytes, get it wrong and performance can drop, perhaps in the last hour of the race but also over days of sweating for hours on end; too much salt and the body can balloon up with water.

Drink, drink, drink say the team managers but the more tired a rider, the less they care. If a rider is consuming 20 bottles in a stage someone has to go and fetch a lot of it. But what if the hardest part was trying to do all this while riding past thousands of people sat in the shade with their picnic ice boxes filled with cold drinks?