Effect of inspiratory muscle strength training on inspiratory motor drive and RREP early peak components.

This study investigated the effect of inspiratory muscle strength training (IMST) on inspiratory motor drive [mouth occlusion pressure at 0.1 s (P(0.1))] and respiratory-related evoked potentials (RREP). It was hypothesized that, if IMST increased inspiratory muscle strength, inspiratory motor drive would decrease. If motor drive were related to the RREP, it was further hypothesized that an IMST-related decrease in drive would change RREP latency and/or amplitude. Twenty-three subjects received IMST at 75% of their maximal inspiratory pressure (Pi(max)) with the use of a pressure threshold valve. IMST consisted of four sets of six breaths daily for 4 wk. P(0.1) and the RREP were recorded before and after IMST. Posttraining, Pi(max) increased significantly by 36.0 +/- 2.7%. P(0.1) decreased significantly by 21.9 +/- 5.2%. The increase in Pi(max) was significantly correlated to the decrease in P(0.1). RREP peaks P(1a), N(f), P(1), and N(1) were identified pre- and post-IMST, and there was no difference in either amplitude or latency for those peaks. These results demonstrate that high-intensity IMST significantly increased Pi(max), decreased P(0.1), but did not change the RREP.