Inspiratory Muscle Training: Improvement of Exercise Performance With Acute Hypoxic Exposure

To determine whether chronic IMT improves submaximal exercise performance with acute hypoxic exposure. Fourteen endurance-trained men completed a 20km cycling time trial (TT) in normobaric hypoxia (F O =0.16) before and after either 6wk of an IMT protocol consisting of inspiratory loads equivalent to 80% of sustained maximal inspiratory pressure ((SMIP); n=9), or a SHAM protocol (30% of SMIP; n=5). In the IMT group, 20km TT performance significantly improved by 1.4 ± 2.0% (P=0.032) after the 6wk intervention. The significantly faster TT times were accompanied by a higher average V̇ (pre vs. post: 99.3 ± 14.5 vs. 109.9 ± 18.0 L·min , P=0.012) and absolute oxygen uptake (V̇O ) (pre vs. post: 3.39 ± 0.52 vs. 3.60 ± 0.58 L·min , P=0.010), with no change in ratings of perceived exertion or dyspnea (P>0.055). There were no changes in TT performance in the SHAM group (P=0.448). Our data suggest that performing 6wk of inspiratory muscle training may benefit hypoxic endurance exercise performance lasting 30-40 minutes.