In one sense, the story that a cyclist loses weight and goes a lot faster when he starts going up mountains is not exactly news. However, the information released by Chris Froome via Esquire magazine makes it clear that this is pretty much what happened to the Kenya-born Briton over the four years between his time as a callow novice at the UCI’s World Cycling Centre in Aigle, Switzerland, and his emergence as a Grand Tour contender with Team Sky in late 2011.
The direct comparison between Froome’s figures in 2007 and the various tranches of data released this year make reassuring reading for those who want to believe in the Team Sky leader, in that there is a correlation between most of the figures on show. In 2007, Froome’s sustained power output is recorded at 420 watts, giving him a power-weight ratio of 5.56 watts per kilogramme due to his higher weight.
On 14 July this year, his average power output over 41 minutes climbing to the La Pierre-Saint-Martin ski station in the Pyrenees was 414 watts, before adjustment for the fact that the Stages Powercranks on which Sky record performance tend to over-record by around 6% when used in conjunction with the ovalised cranks ridden by the team, a fact the Guardian verified with the manufacturers after the figures were released by Sky’s Head of Performance, Tim Kerrison.
Two days later, Froome’s unadjusted average power at the Plateau de Beille ascent was 414 watts again. His sustained power output recorded in the GSK test was 419 watts, which again seems consistent. His power-weight ratio in the GSK test, if adjusted to take account of his lower weight during the Tour, would be around 6.2 watts per kilo, which ties in with tests done for another Tour winner in recent years about whom no questions have been raised.
What is not in doubt, however, is the massive increase – 10% approximately –that Froome would have achieved in his power-weight ratio, by dint of losing fat while maintaining his muscle power. That is the big challenge in training for professional riders, but it is one that is advertised by reputable trainers of amateur cyclists on the internet so it is not exactly a secret or dubious practice. It is an area in which Sky have several years of experience with other riders such as Sir Bradley Wiggins and more recently Geraint Thomas. The limitation here is a mental one – the rider’s ability to stick to his diet – as is made abundantly clear by the fact Froome put on 3kg in three weeks after the Tour.
The leaked figures for Froome’s ascent of Mont Ventoux in July 2013 were where the data release story began in July, when these were married to YouTube footage of the climb that Team Sky tried to ban. At the time questions were asked about Froome’s heart-rate on the climb, which was lower than might have been expected for a top professional cyclist. If there is a lack of consistency across the various sets of data, it is in Froome’s heart rate, but current training science contends that heart-rate is subject to so many variables that it is far less reliable as a measurement of performance than power.
Froome’s 2007 test shows a resting heart rate of 32, which is spectacularly low. His maximum heart rate in the test is also low, 161 beats per minute, particularly compared with the maximum figure of 174 beats recorded on the La Pierre-Saint-Martin climb. However, merely being fatigued due to a high training load can suppress maximal heart rate by 10-15 beats, as any amateur who has used a pulse monitor will testify. Conversely, he clearly hit the Pierre-Saint-Martin climb fresh after a rest day having enjoyed a smooth first week to his Tour de France.
Wiggins and Dave Brailsford have both pointed out, concurring with Vincenzo Nibali and Alberto Contador, that the release of the data in Esquire will probably not change many minds, any more than the details put out in July did. But while other cyclists – Thibaut Pinot and Tom Dumoulin spring to mind – have put far more out in the public realm, with fewer questions, Froome is at least making steps in what has to be the right direction.
The full article appears in the January issue of Esquire on sale 8 December, also available as a digital edition
