Chris Froome's physiological test results explained

Tour de France winner Chris Froome has released the results of physiological tests in a bid to prove that he did not cheat in this year's race.

He underwent the tests in London in August and the results have now been published in Esquire magazine. A separate scientific paper is also to be published.

The results are at the "upper limits for humans", says The Times. "That conclusion is not a surprise, given that Froome has twice won the toughest endurance event in his sport, yet it may not be enough to answer his detractors, whose cynicism stems from years of performance-enhancing drug use in cycling."

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Froome was at the centre of controversy in this year's race with French media openly questioning his performances. Many fans turned against him and he was even showered with urine during one stage of the face

The new figures were released alongside data from equivalent tests taken in Switzerland in 2007. They show that Froome's "success can be put down to a massive loss in weight, helping to explain his improvement from also-ran to Tour de France winner", says The Guardian. He has slimmed down from 75kg to a racing weight of 67kg without losing any power, notes the paper.

Power to weight ratio

During the tests Froome produced almost six watts of energy per kilogramme of body weight. The scientists then extrapolated the data, as Froome was carrying slightly more weight than he had in the summer, and came up with a figure of 6.25w/kg.

That is a huge improvement on the 5.56w/kg he recorded in 2007.

"What is clear is that Froome increased his power to weight ratio by around ten per cent," says the Guardian. "Enough to make a massive difference while climbing the Tour's mountains."

The figure is also a realistic one. During this year's race French TV estimated from footage of Froome that he was producing around seven watts, which would put him into, what Cycling Weekly calls "Lance Armstrong territory".

"The main criticism Froome faced over the summer was simply that he was too fast to be plausible, especially uphill," adds the magazine. "Make no mistake about it, this is a very big number. But it’s a lot less than 7w/kg. Is it believable? For a Tour winner, yes. On it's own it's certainly not enough to prove Froome's critics right."

VO2 Max

The second key figure is Froome's VO2 max - the maximum volume of oxygen that an athlete can use, measured in millilitres per kilogramme of body weight per minute.

Froome's reading was 84.6, extrapolated to 88 at race weight. "The general population has a VO2 max of 35 to 40, with highly trained individuals in the 50s and 60s," says the Times. "A few athletes have been measured in the 90s, including three-time Tour winner Greg LeMond."

The figure is "high, but not off the scale", says the Guardian, although it was the highest ever seen by the scientitsts testing Froome.

Blood tests

Froome's haemoglobin and red blood cell levels were within normal parameters but do not reveal much, says Cycling Weekly. "The problem with them is really that they only cover two samples, both taken over the summer. To tell very much we'd need more samples taken over the season to see the changes and trends," it says.

What's missing?

"It would be interesting to see would be some anaerobic tests," suggests Cycling Weekly. "That side of his physiology profile is ignored, yet it was very important in the early moments of the mountain attacks that attracted so much attention."

However, there is "no smoking gun" in the results, but they do not prove anything either, says the magazine.

"If you could prove athletes were clean or doping with physiological tests, the World Anti-Doping Agency would have been doing it for years."