The ER was conducted following 2 days of light training. Subjects were told to prepare for the ride as they would for a typical race, which included usual dietary and hydration practices on the days leading up to the ride. Each cyclist was weighed prior to warm-up and 10 min after the ride in the same dry clothing. Ambient temperature was kept constant at 21 °C, while fans were used to aid heat convection. During the ride subjects were free to consume water, sports drinks (e.g. Gatorade®) and food (e.g. Powerbars®). Once the ride began, shifting of gears was not permitted to minimize any slight change in intensity.
All physiological measurements were taken concurrently before, during and after exercise while the subject was seated on his racing bike, with hands resting on the handlebars. The baseline readings were done 15 min after arterial catheter insertion, but before warm-up. Exercise measurements were taken at minute 15, 30 and every 30 min thereafter until exhaustion. Typically the participant informed the investigators when he had less than 10 min remaining until exhaustion, at which point a final set of data were collected, labeled ‘End’. After exercise, the participant pedaled at 100 W for 4 min followed by 1 min of rest while remaining on the bike. At this time, a final set of data were collected and labeled ‘Post’ exercise.