Variable effects of respiratory muscle training on cycle exercise performance in men and women.

Respiratory muscle training (RMT) has been proposed as an effective means to increase the strength of the inspiratory muscles and improve exercise performance. The purpose of this study was to examine the effect of RMT on cycling time to exhaustion (TTE) and to determine any potential sex effect. We hypothesized that RMT would improve maximal inspiratory pressure (MIP) and TTE to a similar degree in men and women. Males (n = 7; mean (+/- SD) age, 22.1 +/- 1.5 y) and females (n = 8; mean (+/- SD) 24.5 +/- 4.9 y) performed an incremental cycle test to determine maximal oxygen consumption ((.)VO(2) (max)) (day 1), followed by a familiarization TTE (day 2) and baseline TTE (day 3) at 80% maximal work achieved during the ((.)VO(2) (max)) test. Subjects then completed 5 weeks of respiratory muscle training (RMT) (5 d/week, 2 sets of 30 inspirations against 50% MIP). Four training sessions per week were performed at home and the 5th was supervised, during which the threshold load was increased if necessary. Following RMT, subjects completed 2 TTE tests (days 4 and 5). MIP increased in each subject (37% +/- 18%, P < 0.05). There was no difference between men (pre = -100 +/- 20 vs. post = -140 +/- 29 cmH(2)O) and women (pre = -90 +/- 28 vs. post = -117 +/- 28 cmH(2)O). Baseline TTE (male = 301 +/- 122 s; female = 338 +/- 98 s) was shorter in comparison with the best of the 2 TTE-post tests (male = 353 +/- 68 s; female = 416 +/- 116 s; P < 0.01), but not when compared with days 4 or 5 (P > 0.05). RMT increases MIP and may improve exercise performance; however, improvements are variable with no differences between men and women.