Chris Froome's very fast ascent of Ax-3-Domaineslast Saturday has, yet again, raised doubts that the Tour de France is clean of drugs. Why?
Here's how I understand things work:
An analysis of the biomechanics of hill climbing and human physiology can give an insight as to the possibility of the use of doping:
- To get up a hill of a known height and within a certain time, we can work out quite precisely, the energy required to get the top - given that we know the weight of the rider. This is worked out as Watts of energy per Kilogram per minute.
- The number of Watts can also be converted into oxygen consumed by the athlete which is expressed as the number of milliliters of oxygen consumed per kilogram body weight per minute (mlO2/Kg/min). many readers will be familiar with this as a measure of human performance.
- A fit male produces about 45-60ml/Kg/min. A "clean" Olympic standard cyclist or runner may produce a work rate as high as an eye-popping 90ml/Kg/min but not for longer than about 20 minutes of sustained effort.
- The big hill climbs during the Tour de France, involve steep, sustained efforts for as long as 40 minutes, at altitude (meaning less oxygen than at sea level which means lower oxygen uptake which means lower performance) and this is usually at the end of a long and very hard day on the bike. One would assume that the Watts produced would be on the low side - not high - due to fatigue and altitude taking the gloss off the performance.
- It is generally considered that a sustained performance of no greater than 6 Watts per kilogram per minute is humanly possible. Any higher than 6 Watts and the suspicion that doping may be present is raised.
- We are fortunate to have the benefit of many historic performances on the big hills of the Tour by confessed drugs cheats such as Lance Armstrong, Tyler Hamilton and Floyd Landis. We can work out how many Watts per minute these athletes produced while climbing. Typically, these athletes produced work outputs that well exceeded 6 Watts per kilogram per minute.
- Froome's estimated output was somewhere between 6.2 and 6.7 Watts for last weekend's climb. That's over 90mlO2/Kg/min of sustained effort climbing a steep hill after hours of fast, flat racing! The rest of the field was less than 6 Watts, the predicted maximum for "clean" athletes.
His performance does raise the question of doping but is not proof one way or another. But, given the tarnished record of the Tour, it is only right that the spotlight be shone brightly on any statistical outliers (Froome is definitely a statistical outlier in terms of Watts produced).
Questions:
- Has Froome and his Sky team found a new designer drug that is currently undetectable?
- Have they found a legal loophole, such as with Alberto Salazar's runners (Rupp and Farrah) who have been medically diagnosed as being "hypothyroid" and therefore allowed to inject thyroxine before races?
- have they simply got the best chemists and the best technology that money can buy, better able than the rest to use doping known products such as EPO, steroids and masking drugs, taking them to the closest margins of triggering a positive on the doping test, but not quite?
- Did he simply pull a once in a lifetime freakish blinder of a performance out of the bag?
We may never know and, unless another cyclist produces a similar blinder as the one turned out by Froome, all he needs to do from now in to is to lay low (if he were cheating), concentrating on getting to the end of the Tour in one piece.
For details and discussion about how performance is calculated and related to the Tour de France:
http://www.sportsscientists.com/2013/07/the-power-of-tour-de-france-performance.html
And analysis of Froome's effort in detail:
http://www.sportsscientists.com/2013/07/tour-rest-day-pondering-unanswerables.html
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