With three Tour de France victories in the last four years, Chris Froome is arguably the world's supreme endurance athlete. 

One of the keys to Froome's success is his lung power. The 31-year-old has a VO2 max (the maximum rate of oxygen consumption) of 88.2. To give you some context, the average VO2 max for an active person is between 40 and 50.

A clear sign of the physical development Froome has undergone in the last decade is his weight. In 2007, Froome's race weight was 11 stone 9, but for this year's Tour he got it down to 10 stone 6.