Repeated-sprint cycling does not induce respiratory muscle fatigue in active adults: Measurements from the POWERbreathe® inspiratory muscle trainer

This study examined respiratory muscle strength using the powerbreathe® inspiratory muscle trainer (i.e.,‘s-index’) before and after repeated-sprint cycling for comparison with maximal inspiratory pressure (mip) values obtained during a mueller maneuver. the s-index was measured during six trials across two sessions using the powerbreathe® and mip was measured during three trials in a single session using a custom-made manometer in seven recreationally active adults. global respiratory muscle strength was measured using both devices before and after the performance of sixteen,6-s sprints on a cycle ergometer. intraclass correlation coefficients for the powerbreathe® s-index indicated excellent (p < 0.05) trial-to-trial (r = 0.87) and day-to-day (r = 0.90) reliability yet there was no significant correlation (r = -0.35,p = 0.43) between the s-index measured using the powerbreathe® and mip measured during a mueller maneuver. repeated-sprint cycling had no effect on respiratory muscle strength as measured by the pow-erbreathe® (p > 0.99) and during the mueller maneuver (p > 0.99). the powerbreathe® s-index is a moderately reliable,but not equivalent,measure of mip determined during a mueller maneuver. furthermore,repeated-sprint cycling does not induce globalized respiratory muscle fatigue in recreationally-active adults. © 2014,journal of sports science and medicine.