Effects of altitude on top speeds during 1 h unaccompanied cycling.

The present world record for 1 h unaccompanied cycling (55.291 km) was set by T. Rominger in November 1994 at sea level (Bordeaux, France). However, maximal aerobic cycling performances can be expected to increase at altitude because, for a given air temperature, air density decreases more than VO2max. The combined effect of these opposite trends results in an improvement of performances. In this study, based on the aerodynamics of track cycling, and assuming an average decrease of VO2max with altitude as from the literature, we show that the ideal altitude for Rominger is 4000 m where he could cover 60.1 km in 1 h. To our knowledge, only two cyclists attempted at close time intervals to set the 1 h record at sea level and at altitude (Mexico, 2230 m above sea level): F. Moser and J. Longo. Their increase of performance with altitude was only about 50% of that predicted on the basis of similar calculations as performed on Rominger. This suggests that the decrease of VO2max resulting from altitude is greater for athletes than for average trained subjects and/or that the fraction of VO2max that can be maintained throughout 1 h decreases with altitude.