Inspiratory muscle training and its effect on oxygen saturation and perceptions of effort and dyspnoea during a trek to Everest base camp.

The effects of inspiratory muscle training (IMT) were evaluated at rest and during exercise in normobaric hypoxia (NH) and then an 11-day trek to 5300m. A 7-week IMT program was completed by 6 females and 3 males (age 34.8 ± 10.0 years) randomized to IMT (n = 4) or placebo [P (n = 5)]. A Powerbreathe was initially set at a resistance of 50% (IMT) or used at 15%ofmaximal inspiratory pressure (MIP) throughout (P). A self-paced walking test was completed before and after training at PIO2 = 104.1mmHg, 3440m (NH1); PIO2 = 85.9 mmHg, 4930m (NH2); and at 3440m during the trek (HH). Exercise data were interpolated to 4.8 km/hour to evaluate training effects. Patterns of change suggest possible benefits of IMT, but due to small group sizes and variability, these trends are not significant. MIP increased by 6% and 4% following IMT and P. Pulse oxygen saturation (SaO2) during exercise in NH2 increased by*4% following IMT, with no change in P. Decreases in resting SaO2 during the expedition (4930m) were attenuated in IMT (85.0 ± 3.61%) compared to P (80.0 ± 5.87%). Comparisons between NH1 exercise post-training and HH showed a decrease in perceived dyspnoea and effort in IMT ( - 0.3 and - 0.7) but an increase in P ( + 0.7 and + 2.6). Nonsignificant trends within the data suggest that the altitude-induced decrease in resting and exercise SaO2 and intensified perceived effort and dyspnoea during exercise were attenuated following IMT. However, further research is required to establish any beneficial effect of IMT.

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