The purpose of this study was to investigate the effect of an exercise duration similar to triathlon's cyclism event (approximately 1 hr), on factors determining the freely chosen cadence. Nine trained triathletes completed a cycling track session conducted at a speed corresponding to 75% of maximal heart rate. This session was composed of five submaximal rides performed at five cadences presented in a random order (65, 80, 95, 110 rpm and freely chosen cadence) realized before and after a 1-hr exercise at the freely chosen cadence. Results show, during the first condition, that triathletes choose spontaneously a cadence (90, 1+/-10, 7 rpm) close to the neuromuscular optimum (89, 6+/-1, 1 rpm) while at the end of exercise, a decrease of the freely chosen cadence (82, 8+/-8, 7 rpm) was observed toward the energetically optimal cadence (78, 6+/-5, 8 rpm). These findings suggest the hypothesis of an adaptation of the movement pattern with the exercise duration in order to minimize the energy cost rather than the neuromuscular cost of cycling.