I recently watched a flat stage of the Tour de France. 40C (104F) and the tarmac was softening. As if racing in the heat weren’t enough, the sticky tarmac makes the racing harder. The highs have been around 100F in the Denver area. We start our rides at 7 a.m. when it’s in the low 70s. The pros start in the afternoon!
Looking back the race was decided on Stage 11 from Albertville to the Col du Granon: 151.7 km (94.1 mi.) with a massive 4,692m (15,394 ft.) of climbing. The summits of two climbs were over 2,000m: the Col du Galibier 2,642m / 8,867 ft. (11.9 km averaging 7.1%) and the Col du Granon 2413m / 7,916 ft. (11.3 km averaging 9/2%).
When the racers signed in at the start in Albertville it was already 31C (88F). The Jumbo-Visma riders were wearing ice vests.
Cycling News reported, “Jonas Vingegaard (Jumbo-Visma) took control of the Tour de France with victory atop the Col de Granon on one of the most dramatic days in the rich history of the race.” Vingegaard won in 4:18:02 (35.28 km/h / 21.9 mph)
Why Racers Get Hot
The racers overheat in several different ways and understanding these will help you perform better in the heat:
- Energy production. The human body is only 20 to 40% efficient, which means only 20 to 40% of the energy a racer gets from eating is translated into forward motion — the rest becomes heat. The racer has to dissipate this heat or the core temperature will rise. Energy production and heat dissipation are the primary factors in overheating.
- Radiation. When the sun is out, the peloton gains heat from direct radiation as well as from radiation reflected from the pavement. They may also gain heat from radiation through diffuse clouds. The higher the sun is in the sky the more radiation heats a rider up. Because the stages start in the early afternoon the peloton is exposed to maximum radiation.
- Respiration. If it’s really hot, the racer may gain heat through breathing. Hot air feels harder to breathe.
- Conduction. The rider also gains heat through hot parts of the bike.
- Convection. If the air is hotter than a racer’s body, the body absorbs heat.
Increasing the racer’s sweat rate and radiation from increased blood flow to the skin account for about 85% of the body’s cooling. Because sweat rate is so important adequate hydration is key.
A racer can only absorb so much fluid per hour. Different studies report maximal rates of intestinal fluid absorption ranging from 600 ml (20 fl. oz.) to 1.6 liters (54 fl. oz.) per hour. When climbing hard a racer could easily sweat out two liters per hour, more than the racer can drink! On hot climbing days racers get dehydrated despite drinking as much as possible. And they still climb fast!
Glucose is the primary fuel during a race. Glucose is stored as glycogen. A racer can store about 450 grams of glycogen. With each gram of glycogen, the body also stores three grams of water for a total of about 1.35 L of water. During a race the riders are drawing on their glycogen stores, which provides additional hydration.
- Pre-hydrate. Each rider is weighed in the morning. He then drinks enough at breakfast so his body weight is normal and continues to hydrate to the race start.
- Electrolytes in diet. Each team has a chef to ensure the riders have the best nutrition. In addition to plenty of carbs and also protein, the diet includes plenty of electrolytes: sodium, potassium, calcium and magnesium.
- Race drinks. Depending on preferences and stomach issues, a racer drinks water, a sports drink and Coke.
- Electrolyte drinks. On some teams the soigneurs prepare drinks customized for each rider; the composition of these drinks is proprietary. Some teams use a commercial sports drink provided by the sponsor. Other teams outsource custom drink mixes and have them tested for purity to be sure they won’t present problems with drug testing.
- Post-race. The riders are weighed after every stage and then they each drink 1.5 times the weight lost, i.e., 24 fl. oz. for every pound lost (1.5 L / kg). Many of the teams have proprietary recovery drinks. In general, the drinks contain simple sugars, sodium, potassium, calcium, magnesium, essential amino acids, anti-oxidants and B-vitamins. (Pedialyte is the most equivalent commercial drink.)
Eat, Race, Win is a terrific video on Amazon about racing and race nutrition. It follows the Orica-Scott team in the 2017 Tour de France as they race to put Yates in the white jersey as the best young rider. Hannah Grant, the chef for the team, narrates the video and shows how her nutrition for the riders supports superb racing. Eat, Race, Win has the highlights of the race action and takes you behind-the-scenes as Sports Director Matthew White encourages his nine riders to victory.
Does Dehydration Matter?
The American College of Sports Medicine (ACSM) recommends drinking enough during exercise to prevent excessive dehydration (>2% body weight). Dehydration is expressed as a percentage of body weight. If a 160-lb (73 kg) rider loses more than 3.2 lbs (1.5 kg) during the course of a ride, the cyclist is more than 2% dehydrated.
If dehydration significantly inhibits performance, then as the day wears on the riders would slow down and sprints for king of the mountain points and flat-out sprints at the finish would be impossible. Clearly dehydration doesn’t affect their performance!
Over-Hydration Is Dangerous
The ACSM also recommends not drinking so much fluid that excessive changes in electrolyte balance result. Too much fluid can dilute the blood sodium level to a dangerously low level (hyponatremia). The sodium concentration in electrolyte drinks is less than the sodium concentration in the blood so drinking too much of a sports drink can also cause hyponatremia. Hyponatremia can cause the body to retain fluid, which causes bloating. As the rest of the body bloats up the brain also tries to swell; however, it can’t because of the skull. The increasing pressure on the brain can be fatal. If you notice swelling around the top of your socks or your gloves or a ring on a finger you are retaining fluid. Stop drinking until the swelling goes down!
Bottom Line For You
- Drink enough daily that you stay hydrated. The old maxim of “drink eight glasses of water a day” doesn’t apply. Fluid needs differ by body size, age and the temperature depending on the season and where you live. This article in the New York Times explains How Much Water Do You Actually Need?
- Satisfy thirst on a ride. Current researchers on hydration and hyponatremia recommend a simple rule of thumb: drink if you are thirsty, and otherwise don’t drink. The need to drink is also a function of habit, ritual and the desire for a warming or cooling drink. Further, if you are age 65 or older, your thirst response is blunted, a dynamic that increases with age.
- Drink what you like. There are no performance enhancing drinks – if there were they’d be banned by the World Anti-Doping Agency. There’s a recipe for a homemade sports drink on my website that many of my clients like.
- Drink, don’t douse. You want to prevent significant dehydration so your blood can move heat from your core to your skin. Unless you have unlimited fluids, drink what you have instead of pouring it on your head. The pros have unlimited fluids, drink all their bodies can absorb and douse themselves with the rest.
- After a ride rehydrate by drinking enough that you urinate with a good clear stream. The American Dietetic Association recommends after exercise you should drink adequate fluids to replace your sweat losses during the ride, approximately 16 to 24 fl. oz. (2 to 3 cups) for every pound (1 to 1.5 L per kg) you’ve lost. Drinking more than you lost during the ride both replaces the fluid you sweated out and meets your fluid needs during your recovery. Drinks with carbs are better than plain water; however, if you prefer water also eat some carbs. There are no magic recovery drinks.
- Effective Cooling
- How to Ride Safely in the Summer Heat
- Nature Breaks and Dehydration
- 12 Myths About Hydration
I researched what pro riders consume before, during and after a stage and discussed the results with cycling nutrition experts. We all require energy and replenishment of lost minerals and nutrients when we ride. Eating and drinking like the pros offers us the same nutritional benefits, which we can customize to our own needs – typically at a fraction of the cost of commercial sports food and drink, if we choose to make our own.
I worked with a professor of nutrition and an expert on hydration and electrolytes (both experts are cyclists) to create a dozen recipes for sports drinks, gels and food. They’re easy to make, with known, unprocessed ingredients, and can be tailored to your specific taste and needs.
The 15-page Eating and Drinking Like the Pros is $4.99.
You can learn more about the science of riding in the heat, and managing your fluids and electrolytes, in my two-part eArticle series:
1. Cycling in the Heat, Part 1: Ride Management is 19 pages and covers how to acclimate to hot conditions, how to train in hot months, what to wear, eat and drink, how to cool down if you overheat, and how to deal with heat-related problems.
2. Cycling in the Heat, Part 2: Hydration Management is 21 pages and covers how to determine how much you should drink depending on your physiology and sweat rate, how best to replace your fluids and electrolytes, the contents of different sports drinks, how to make your own electrolyte replacement drinks, how to rehydrate after a ride, and how to deal with hydration-related problems.
The cost-saving bundled eArticles totaling 40 pages Cycling in the Heat Parts 1 and 2 are just $8.98 (a 10% savings).
Coach John Hughes earned coaching certifications from USA Cycling and the National Strength and Conditioning Association. John’s cycling career includes course records in the Boston-Montreal-Boston 1200-km randonnée and the Furnace Creek 508, a Race Across AMerica (RAAM) qualifier. He has ridden solo RAAM twice and is a 5-time finisher of the 1200-km Paris-Brest-Paris. He has written over 40 eBooks and eArticles on cycling training and nutrition, available in RBR’s eBookstore at Coach John Hughes. Click to read John’s full bio.