What Does it Take to Ride the Tour de France?

Edmund R. Burke, Ph.D.

Riding an event such as the Tour de France pushes a cyclist to extremes of athlete endurance. Lasting up to three weeks and over 4,000 km participation in a major tour requires of the cyclist an aerobic capacity for prolonged exertion and an anaerobic potential to be called upon in breakaways, hill climbing, and 'all-out' sprints. While much laboratory data has been collected over the years on professional tour cyclists, it has only been recently with the advent of power meters and heart rate monitors that we can now obtain data on the power, speed and heart rate of these athletes while racing.

Power and Physiological Demands

The mean average time spent training and racing on the road for professional cyclists preparing for a major tour is between 30,000 and 35,000 kilometers (km) reports Dr. Asker Jeukendrup a physiologist working with Team Rabobank. This approaches an average of 600 km a week for professionals versus about 250 km for top amateur cyclists. Dr. Jeukendrup also has reported that top European pros he has worked with race and average of 101 days per year. Significantly more than amateur cyclists.

Dr. Jeukendrup has power data on a world class cyclist riding in the peleton during a stage of the Tour de France for six hours at an average speed of 40 km/hour. Because of the effect of drafting in the large group his average power output was 98 watts. If riding by himself on level roads, no wind and in an aerodynamic position he would have had to average 275 watts to maintain this speed. There are several reports of cyclists using power meters in races of over 200 km and their power outputs varied between 150 to 300 watts for the race.

Data from several researchers shows that professional cyclists produce power outputs of between 320 and 450 watts during time trials ranging from 5 to 70 km in major tours. These cyclists absolute power output will obviously depend upon duration of race, the course profile and whether the cyclists are in contention for overall GC or if they are going for a stage win.

Dr. Alejandro Lucía, Universidad Europea de Madrid, Spain, has predicted that Lance Armstrong on his ascent of the Alpe D¹Huez (a 14 km climb of 8% mean gradient) in the 2001 Tour de France produced one of the greatest performances in the history of cycling: 38 minutes of near-maximal to maximal effort at an estimated mean power output as high as 475-500 watts! His average speed was 22 kilometers/hour, which he reached at a mean cadence of about 100-rpm using a 39 x 23 gear. Lance would have been averaging about 7 watts/kg.

Additional research by Dr. Sabino Padilla from the Athletic Club de Bilbao, Basque Country, Spain has determined exercise intensity during time trials in professional cyclists while competing in the three major tours(Tour de France, Giro and Vuelta) by monitoring heart rate. Heart rate was recorded in a number of time-trials, including prologues (<10 km), short time trials (<40 km), long time-trials (>40 km) and uphill time-trials. He showed significant difference in heart rates between the various time trials, which was largely a function of the different duration of the events. The highest heart rates were recorded during the short prologues (88-90% of max heart rate). The short time-trials of 27-36 km were raced at 82-88% of max heart rate, and the longer (49-km) time trials were raced at a slightly lower intensity of between 79 and 84% of heart rate max. Speeds in these events on relatively level roads averaged 46.3km/h, 43.lkrn/h and 44.7km/h respectively. As would be expected, speed in the uphill time-trial was significantly lower (40 km/h).

Dr, Lucia has reported that during a 60-km time-trial in the Tour de France, several cyclists he was monitoring spent 95% of race time (70 minutes) at HR between 88% and 100% of max heart rate. In that time trial, it was estimated that the winner maintained an intensity of >90% of V02max for 70 min, averaging 50 km/h.

Energy Expenditure and Food Intake

Dr. Wim Saris, University of Masstricht, Netherlands has studied cyclist during the Tour de France using a highly reliable method of determining energy expenditure and has estimated that energy expenditure averaged 5.700 kilocalorie (kcal) per day with extremes of up to 9,500 kcal a day during long, mountainous stages. Despite the very high-energy expenditures on most days, the riders maintained energy balance fairly well. On some of the very hard days it is difficult to match the energy expenditures and often the riders are in slight 500- to 1,500-kcal negative energy balance. On rest and shorter time trial days they seem to compensate for this, and over the course of three weeks they are usually able to maintain their body weights fairly well.

Cyclists during the Tour appear to take in adequate carbohydrates, with Saris reporting carbohydrates accounting for about 60 percent of kilocalorie intake, or greater than 800 grams/day or 12 to 13 grams/kg of body weight. Protein intake averages about 14 to 18 percent and fat intake about 23 to 25 percent of daily kilocalorie intake. A fair amount of the daily carbohydrate intake is taken during the stage in the form of sports drinks and gels. During recovery the cyclists average 1.1 grams/kg bodyweight of carbohydrate in the first six hours after the stage, with the addition of some protein to the recovery drink.

During the second and third week of the Tour de France, some of the riders suffer from gastrointestinal problems and they may not be able to tolerate the large amounts of food. After hot stages when dehydration may be considerable, the incidence of gastrointestinal problems is more frequent and in those cases it is important to re-hydrate first to reestablish normal gut function. Some of the cyclists have to resort to intravenous infusions of saline and glucose after the stage to help restore normal body fluid levels and aid in rapid recovery. The riders are therefore encouraged to eat and drink as much as possible during the stages. When the tempo picks up in the final two hours of a stage it is difficult to eat and drink. However, the more disciplined cyclists are learning to increase their food and drink intake considerably during more recent tours.

Laboratory Data

In 1999, Dr. Padilla summarized some of the physiological laboratory testing of professional road cyclists in the journal Medicine and Science in Sports and Exercise. He measured the maximal and lactate threshold responses of members of a Spanish professional road cycling team (Banesto) whose subjects included five-time Tour de France winner Miguel Indurain, as well as riders who had won other stage races in the Giro and Vuelta. According to their role in the team, the cyclists were categorized as either flat terrain, time trial am, all terrain or uphill specialists.

The maximal power outputs and aerobic capacities of the flat terrain and time trial riders were significantly higher than the all terrain and uphill riders. The highest average maximum wattage output (Wmax) was measured in the flat terrain cyclists (461W), which was higher than all terrain and uphill cyclists (432 and 404W). The time trialist wattage (457W) was also significantly higher than uphill cyclists.

Absolute V02 max values were also significantly higher in flat terrain and time trial cyclists than uphill cyclists (5.67 and 5.65 versus 5.05 Liters/minute), but none of these were statistically different from all terrain cyclists (5.35 Liters/minute). These findings are predictable based on the specialized role of the team members, and several anthropometric measurements, which reveal that the flat terrain and time trial cyclists were also taller, heavier, and had greater body surface areas than their all terrain and uphill cyclists.

However, when these same physiological measurements are expressed relative to a cyclists body weight, a different picture emerges, with the uphill cyclists gaining the top of the podium. The uphill cyclists had the highest power: 6.47 W/kg) followed by time trial, all terrain and flat terrain (6.41, 6.35 and 6.04 W/kg, respectively. V02max values expressed relative to body weight (ml/kg/minutes) were significantly lower in flat terrain than all other groups: 74.4 for flat terrain versus 79.2 for time trail, 78.9 for all terrain and 80.9 ml/kg/min for uphill cyclists.

Although the maximal data reported on these professional cyclists is impressive, perhaps the most impressive physiological characteristic of these cyclists is their power output at the lactate threshold. Both flat terrain and time trial cyclists had higher power outputs at lactate threshold than did all terrain and uphill cyclists; 356, 357, 322 and 308 W respectively. As we have seen in a previous section most professional cyclists complete time-trial races of this distance at speeds in excess of 50 km/h, with many riders able to sustain power outputs over 400 W for the duration. With this information exercise scientists need to exercise caution when using laboratory threshold data in relation to actual racing time trials thresholds. Many cyclists will ride harder in races due to the competition, psychological capacity to put up with more pain, adrenaline and the cheering of the crowd. In other words cyclists will be able to push themselves over their lactate threshold in racing.

Final Spin

Most professional cyclists produce power outputs between 325 and 450 watts while time trialing distances ranging from 5 to 75 km, and between 100 watts while drafting in the peleton and up to 300 watts for long periods of time while riding alone or in small groups in flat stages. The typical laboratory data for these cyclists is a VO2 max of greater than 5.5 Liters/minute and 450 watts, corresponding to a power to weight ratio of greater than 6.5 watts per kilogram. Laboratory lactate threshold data show power outputs at threshold of about 350 watts, with higher wattage outputs well over 400 watts produced while time trialing from the Tour winners.