Changes in cycling efficiency and performance after endurance exercise.

PURPOSE: This study was designed to examine the effects of moderate-intensity endurance exercise on cycling performance, gross efficiency, and 30-s sprint power output.
METHODS: Two separate experiments were conducted. After a controlled warm-up, subjects completed as much work as possible in a 5-min performance test (EXP1) or a maximal 30-s sprint test (EXP2). These initial exercise bouts were followed by approximately 60 min of cycling at approximately 60% VO2peak or an equivalent period of rest (control) before repeating the warm-up exercise and either the 5-min performance or 30-s sprint test. Expired gas for calculation of cycling gross efficiency was collected over the last minute of each warm-up period.
RESULTS: Average 5-min performance power output was significantly reduced (12 W) after exercise in EXP1, and in EXP2 both peak and mean power output were significantly lower (26 and 35 W, respectively). Gross efficiency decreased significantly with exercise in both EXP1 and EXP2. Moreover, the change in gross efficiency was correlated with the change in 5-min performance (r = 0.91, P < 0.01), but not with the change in mean or peak 30-s sprint power output.
CONCLUSIONS: After sustained moderate-intensity cycling significant reductions in 5-min performance, gross efficiency and sprint power output were observed in endurance trained cyclists. The reduction in 5-min performance was related to the exercise induced decrease in gross efficiency.