We thank Silva, Durigan, and Cipriano for their comments regarding our conclusions that repeated-sprint cycling does not induce respiratory muscle fatigue and that the POWERbreathe[R] S-Index is a moderately reliable, but not equivalent, measure of MIP determined during a Mueller maneuver.
We therefore retain our view that the POWERbreathe[R] SIndex is a moderately reliable, but not equivalent, measure of MIP determined during a Mueller maneuver.
The Mueller maneuver is currently the gold standard for measuring MIP and several authors have demonstrated its validity and reliability (Hamnegard et al.
While the POWERbreathe[R] S-index cannot measure an individual's true MIP, we hypothesize that the POWERbreathe[R] S-index can offer a reliable alternate measure of respiratory muscle fatigue to the gold-standard technique, the Mueller maneuver.
During Session 2, six maximal inspiratory breathing maneuvers were performed; three trials using the POWERbreathe[R] and three trials of the Mueller maneuver.
MIP was assessed on a custom-made Manometer by performing the Mueller maneuver immediately before and after the repeated-sprint protocol.
A fully factorial ANOVA with repeated-measures for trial and day was used to compare S-Index values across all six trials for the POWERbreathe[R] while a simple 1-way repeated measures ANOVA was used to determine differences in MIP values across three trials for the Mueller maneuver.
The change in mean and typical error for MIP obtained during the Mueller maneuver calculated for Trial 1 and Trial 2 (trial-to-trial) was 1.