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Chris Froome’s numbers – what do they really mean?

Chris Froome and Dave Brailsford
Peter Stuart
4 Dec 2015

We put Chris Froome’s power numbers in perspective - how much better is he than the rest of the world? We think not all that much.

Chris Froome nearly broke the internet (well, at least the cycling related part of it) yesterday evening when a set of results was released in Esquire magazine after a series of physiological tests done in the GSK human performance labs. But, what do they really mean?

The results surrounded a VO2max test. For those that have never heard of this, here’s the basic process, as completed by Cyclist: VO2 Max Test. Essentially, the intensity of the workout is increased in intervals until the rider can no longer maintain the power and cadence simultaneously. We did this with one-minute intervals, or ‘ramps’, in the case of Froome’s test, the intensity was increased every 30 seconds. Froome reached a power output of 525 watts before failing, and in that last interval his total effective consumption of oxygen is measured to determine his VO2max. That number, in litres, is divided by Froome’s weight to produce VO2max, which was measured at 84.6ml/min/kg (millilitres of oxygen consumed, per minute, per kilogram of weight). Although it’s not stated in the article, he must have effectively consumed around 5.9 litres in a minute to get this figure. Now, that is all extremely good. As stated in the article, the GSK team considered it “off the charts” and far better than anything they’d experienced before. But, one might argue, those results are actually firmly on the charts.

Firstly, let’s compare it to a mere mortal. According to our VO2max testing, above, my numbers came out at 72.6 for VO2max, I reached 440watts for a one-minute ramp. Froome’s numbers are significantly better, he’s about 15% stronger and 15% fitter – an abyss in the world of sport but then I am not a professional athlete and I don’t train every day. So how does Froome stack up against other pros?

Chris Froome retains the yellow jersey, Stage 10 of the 2015 Tour de France

One of the most immediately comparable results is Froome’s threshold test. Threshold power, which GSK described as a figure that an cyclist could maintain for 20-40 minutes, is the point where a rider is likely to tip over to anaerobic energy production and an overload of lactic acid. This is an extremely important figure, as no matter what your VO2max is, your threshold (or FTP) will determine how much power you can deliver in a race scenario. Froome’s figure was 419 watts. While that’s a good 90 watts more than the likes of me, it’s not all that otherworldly when compared to domestic and international pro cyclists.

  • Watch our 3 minute video on the FTP test

During the Vuelta, Tom Dumoulin pushed out 459.6 watts for 8 minutes 29 seconds, and pushed out around 420 watts over the 25 minute climb of the Ermita de Alba. He did that while weighing 70kgs (very similar to Froome) and after a day in the peloton. Contador’s FTP is rumoured to be exactly 420 watts, despite the Spaniard only weighing 62kgs – making us wonder how he manages to haemorrhage time to Froome when the road turns skyward. Then there’s the truly otherworldly figures of Bradley Wiggins – Wiggins famously described pumping out 456watts for 55 minutes in the 2011 world champs, and later stated that he was able to increase his power even further by reducing his cadence. Of course, these comparisons between pros can spark extensive debate and speculation in terms of aerodynamics, weight, tactics and equipment. Yet Froome doesn’t appear to be, as some have suggested, extraterrestrial in terms of power.

To put that threshold power in perspective to the amateur racing scene, UK time trial forums abound with anecdotes of amateur athletes who exceed 400 watts for 10-mile and 25-mile races. As for road racers, some of the top athletes on the domestic pro circuit can be expected to exceed 380watts for a 20-minute effort at a similar weight to Froome (for any stringent readers, a geeky sift through Strava profiles is probably the best way to validate that). For more on this see: How much better are the pros?

Chris Froome climbing on Stage 19 of the 2015 Tour de France

As for Froome’s Vo2max, the figure of 84.6 is certainly high, while the estimate that he would have a figure of 88 when at race weight is extremely high, but it’s not 100% certain that Froome could maintain the same output at a lower weight. However, even that highest estimate sits squarely within the bracket of top cyclists, and perhaps a little lower than some might have expected. Greg Lemond had a Vo2 figure of 92.5, Oskar Svendsen (junior TT world champion) had a figure of 97.5. Froome’s figures are not amongst the highest ever recorded, but are certainly in the territory of the all-time great cyclists. Strangely, they aren’t all that out of reach of many of his rivals, though.

For the doping debate, the test did bring a lot to the table. Froome didn’t create the fabled 7 watts per kilo of power that Lance Armstrong rode at (that would have required a threshold of around 490 watts). The other important result was that his threshold power was 79.8% of his peak power, where some sports scientists claimed that a percentage approaching 90 would have been suspicious. The other part of the test was a comparison with his results in 2007 before his meteoric rise to World Tour victory. They were surprisingly identical, with higher power output beforehand and the only difference in his performance being down to a significant drop in weight, from 75.6kgs down to 69.9kgs, and a further 3kgs down to his race weight.

The real revelation from this test, as far as we are concerned, is that Froome is human.

Full report from GSK here: Chris Froome GSK Report