Oxygen uptake kinetics and maximal aerobic power are unaffected by inspiratory muscle training in healthy subjects where time to exhaustion is extended

The aim of this study was to determine whether 4 weeks of inspiratory muscle training (IMT) would be accompanied by alteration in cardiopulmonary fitness as assessed through moderate intensity oxygen uptake (VO2) kinetics and maximal aerobic power (VO2max). Eighteen healthy males agreed to participate in the study [training group (Tra) n=10, control group (Con) n=8]. Measurements of spirometry and maximal static inspiratory mouth pressure (PImax) were taken pre- and post-training in addition to: (1) an incremental test to volitional exhaustion, (2) three square-wave transitions from walking to running at a moderate intensity (80% ventilatory threshold) and (3) a maximal aerobic constant-load running test to volitional fatigue for the determination of time to exhaustion (Tlim). Training was performed using an inspiratory muscle trainer (Powerbreathe). There were no significant differences in spirometry either between the two groups or when comparing the post- to pre-training results within each group. Mean PImax increased significantly in Tra (P<0.01) and showed a trend for improvement (P<0.08) in Con. Post-training Tlim was significantly extended in both Tra [232.4 (22.8) s and 242.8 (20.1) s] (P<0.01) and Con [224.5 (19.6) and 233.5 (12.7) s] (P<0.05). Post-training Tlim was significantly extended in Tra compared to Con (P