Chris Froome releases data in bid to silence critics
Chris Froome has released his physiological data in an attempt to answer his fiercest critics, but knows he is the only person who can say his performances are 100 per cent clean.
The two-time Tour de France winner's performances in independent laboratory tests were at the upper limits for humans, scientists reported.
That conclusion is not a surprise, given Froome has twice won the toughest endurance event in sport, yet it may not be enough to answer his detractors, whose cynicism stems from years of performance-enhancing drug use in cycling.
Froome told Esquire, which published the figures: "Questions do need to be asked. As long as the questions are fair, I'm happy to answer them.
"What gets my back up is when those questions turn into straightforward accusations.
"I know what I've done to get here. I'm the only one who can really say 100 per cent that I'm clean.
"I haven't broken the rules. I haven't cheated. I haven't taken any secret substance that isn't known of yet.
"I know my results will stand the test of time, that 10, 15 years down the line people won't say, 'Ah, so that was his secret.' There isn't a secret."
In July the 30-year-old was subject to innuendo and scrutiny, doused with urine and called a doper in claiming a second Tour yellow jersey.
Froome's Team Sky squad released performance data during the Tour, relating to the commanding win on stage 10 to La Pierre Saint Martin, in a bid to quell suspicion, but his critics would not be convinced after previously being duped by the likes of Lance Armstrong.
The Kenya-born Briton agreed to undergo independent testing, which took place at GlaxoSmithKline's human performance laboratory in London in August, the results of which were published by Esquire magazine on Thursday evening. A separate scientific paper is also to be published.
Froome's VO2 max - the maximum volume of oxygen that an athlete can use, measured in millilitres per kilogramme of body weight per minute (ml/kg/min) - was recorded as 84.6. At his Tour-winning weight it would correlate to 88.2, according to Esquire.
The general population has a VO2 max of 35 to 40, with highly trained individuals in the 50s and 60s.
A few athletes have been measured in the 90s, including three-time Tour winner Greg LeMond.
Phillip Bell, a senior sports scientist at GSK, told Esquire: "Froome's values are close to what we believe are the upper limits for VO2 peak in humans."
Froome's peak power and sustained power, which he should be able to manage for a period of 20 to 40 minutes, were also measured, at 525 watts and 419 watts, respectively.
The figure corresponds to 5.98 watts-per-kilogram. At his Tour weight of 67kg, it would be 6.25w/kg.
Froome also released blood data readings.
The figures were similar to those attained early in his career, during testing in Lausanne, Switzerland on July 25, 2007.