Disgraced cyclist Lance Armstrong turned fans into sceptics, and the performance of Sky Team’s cyclist Chris Froome raised eyebrows during the Tour de France 2013 when he outstripped his competitors on mountain stretches and achieved times last seen in the “doping era” of the 1990s and 2000s.
All this has fanned the ever-present concern of performance-enhancing drugs and cynics are now turning to science to help them decide whom to trust.
It started on July 6 when Froome powered up the Ax-3-Domaines incline in the Pyrenees.
He completed the 8.9km climb that has an average gradient of 7.46% in 23 minutes and 14 seconds, which got him the yellow jersey and third-fastest time in the history of that stretch. Unfortunately, this places him in infamous company. Armstrong holds the record for this stretch at 22 minutes and 59 seconds.
“The top 10 in that climb is a who’s who of doping and suddenly you put your name on that list,” says Dr Ross Tucker, a sports scientist at the Sports Science Institute of South Africa.
“Only six or seven years ago cyclists who were doping were at the same speed [Froome] is riding now.”
Turning to performance data
Armchair commentators and sports scientists have turned to performance data to decide whether he is cheating, since they do not have access to biological passport data.
“The mountain tells the truth and tells you who is doped. Those are the ideal conditions to calculate the muscle power of each rider according to his build and to install ‘radars’,” cycling performance expert Antoine Vayer and co-author of Not Normal? An insight into doping and the 21 biggest riders from Le Mond to Armstrong to Evans writes in his editorial.
“This power, generated in watts, is the most reliable indicator of presumed doping.”
Power output — defined as watts per kilogram or the power that a cyclist produces per kilogram of the combined mass of his body, bicycle and gear — is particularly important on mountain legs.
“The concept is that once you know the power output it has physiological implications,” says Tucker. “If a car is going at 300km/h, it’s not a Toyota Tazz. It’s a Ferrari.”
The limits of the human body
Tucker, a physiologist by training, says: “We know the maximum physiology of human beings. There’s no physiological possibility to do what those cyclists were doing [during the doping era] — they were either doping or aliens.
“Mathematically and intellectually, you can argue that they are [not doping], but physiologically it’s not possible.”
Previously, athletes were tested for a specific substance and the tests were continually playing catch up as performance-enhancing drugs advanced and entered the playing field.
In 2008, the sport introduced a new method of doping control — the biological passport.
Every few weeks, and sometimes more frequently, an athlete’s blood and urine are tested for biological markers such as testosterone.
Through this the authorities can measure changes in the body that would indicate drug usage.
Froome is "clean"
This data remains confidential, although the Guardian reported that Sky Team head Sir David Brailsford offered the World Anti-Doping Agency access to the team’s data to prove that Froome is “clean” and not cheating.
Since the introduction of the biological passport and more stringent doping measures, cycling has slowed down, which makes Froome’s performance even more suspect.
“Let’s say there was no Chris Froome [in this race]; the Tour de France this year has been slower than any other in the climbs,” Tucker says.
“We’ve been able to predict what the times will be based on the last five years’ worth of performances for any mountain climb. We watch the riders against these predictions. Everyone in the race is slower than these predictions, except one.”
When asked whether Froome could be a miraculous outlier in these statistics, Tucker takes a moment to think.
“The internet is exploding with one accusation after another, some defending blindly, others accusing blindly. If this was a court, both the prosecution and the defence would have a reasonable case.”
Cycling is tricky
To add to the complexity of the problem, cycling is not like running or other endurance sports. In marathon running or the 100m, on average the record will improve by 1% every 10 years, Tuckers says.
But it is not possible to apply this hypothesis to cycling. “Even in the absence of doping it’s tricky for cycling. The bicycle [technology] with its aerodynamics and mass changes performance, although the human being is the same.”
When asked whether he thought Froome was doping, Tucker says: “I’m inclined to say he isn’t doping, maybe it’s naivety, maybe it’s hopefulness.”
It is not inconceivable that Sky Team’s training regime and preparation enabled them to produce a cyclist two percent faster than his competitors, “but the data forces us to question [his performance]”.
Brailsford was dismissive of using performance indicators to decide whether someone had been doping.
“You’ve got to be careful because at some point … you draw a line in the sand and say above that point there is doping and below that point there is no doping. It’s a very, very crude way to think about something,” he told Reuters earlier this month.
No clean line
Tucker concurs. “There is no clean line [saying] that anything below this [point] is clean, and anything else would be doping,” he says, adding that people want an easy definitive answer “that can fit in 140 characters”.
This, however, ignores the complexity of the issue.
He says the importance of performance measurements is to enable people to ask the right questions and then to analyse the answers critically.
“What is driving one person [Froome] to be 2% faster than everyone else? The Sky Team has to try and explain that and their explanation can only be based on evidence, or else it is faith-based answers and it’s Lance Armstrong all over again,” Tucker says, ending on a depressed sigh.
“Cycling fans have post-traumatic stress. Whenever an explanation is offered, even if it’s valid, people are like ‘Ja, right’.”
Cycling jargon cheat sheet
Watts (W): the total power that a cyclist has generated to cycle a certain stretch in a particular time
Watts per kilogram or relative power (W/kg): the power a cyclist has generated per kilogram of his mass, including bicycle and gear
Mean ascent velocity (VAM) or vertical metres per hour (Vm/h): this is the average ascent speed and can be calculated as the relative power multiplied by the gradient
V02 Max: a human body has a maximum threshold of oxygen that it can take around the body and process. V02 Max is often used as a marker of fitness.