Revisiting the effect of posture on high-intensity constant-load cycling performance in men and women.

It was recently observed that inclining the body from a supine to upright position improved the performance of high-intensity, constant-load cycling to a larger extent in men than women (Egaña et al. in Eur J Appl Physiol 96:1-9, 2006), although this gender-related effect was based on a small number of men (n = 5) and women (n = 5). To explore this effect further, we studied the effect of body tilt on cycling performance in a larger and different group of men (n = 8) and women (n = 18). Peak power, peak VO2 and the ventilatory threshold (VT) were determined during an upright maximal graded cycle test, and a high-intensity test (80% peak power) was performed to failure in both the upright and supine positions. Performance was significantly longer in the upright compared with supine position in men (17.4 +/- 7.7 vs. 7.6 +/- 3.4 min) and women (14.1 +/- 6.0 vs. 6.0 +/- 3.7 min). The magnitude of this postural effect was not significantly different between men and women; whereas it was significantly correlated with the relative intensity of exercise expressed as a function of VT (r = -0.39). These data demonstrate that the postural effect on high-intensity cycling performance is not influenced by gender; but that it is related to the intensity of exercise relative to the ventilatory threshold.