Interactive effects of body posture and exercise training on maximal oxygen uptake

To determine the effect of posture on maximal O2 uptake (VO2 max) and other cardiorespiratory adaptations to exercise training, 16 male subjects were trained using high-intensity interval and prolonged continuous cycling in either the supine or upright posture 40 min/day 4 days/wk for 8 wk and 7 male subjects served as non-training controls. VO2 max measured during upright cycling and supine cycling, respectively, increased significantly (P less than 0.05) by 16.1 +/- 3.4 and 22.9 +/- 3.4% in the supine training group (STG) and by 14.6 +/- 2.0 and 6.0 +/- 2.0% in the upright training group (UTG). The increase in VO2 max measured during supine cycling was significantly greater (P less than 0.05) in the STG than in the UTG. The increase in VO2 max in the UTG was significantly greater (P less than 0.05) when measured during upright exercise than during supine exercise. However, there was no significant difference in posture-specific VO2 max adaptations in the STG. A postural specificity was also evident in other maximal cardiorespiratory variables (ventilation, CO2 production, and respiratory exchange ratio). In the UTG, maximal heart rate decreased significantly (P less than 0.05) only during supine cycling; there was no significant difference in maximal heart rate after training in the STG. We conclude that posture affects maximal cardiorespiratory adaptations to cycle training. Additionally, supine training is more effective than upright training in increasing maximal cardiorespiratory responses measured during supine exercise, and the effects of supine training generalize to the upright posture to a greater extent than the effects of upright training generalize to the supine posture.(ABSTRACT TRUNCATED AT 250 WORDS)