Does Inspiratory Muscle Training Reduce Exercise-Induced Arterial Hypoxemia in Female Rowers?

Abstract

During heavy exercise, women demonstrate greater expiratory flow limitation, an increased work of breathing and perhaps greater exercise induced arterial hypoxemia (EIAH) compared to men. PURPOSE: To examine the effects of inspiratory muscle training (IMT) on end-exercise arterial O2 saturation (Sa, O2), lung function at rest and rowing performance in highly-trained female rowers that exhibit severe EIAH. METHODS: Sixteen highly-trained female rowers that exhibited severe (Sa, O2: ≤ 89%) EIAH, were divided into two groups: IMT (T; n=8 age: 19.3 yrs, weight: 65.4 kg, height: 173.1 cm) and control (C; n=8 age: 19.6yrs, weight: 62.4 kg, height: 167.6 cm). T group, in addition to their daily rowing practice, performed IMT by means of a threshold inspiratory muscle trainer (POWER breathe®, IMT Technologies Ltd., Birmingham, UK) for ∼0.5h·d-l, 5 times a week for six weeks. C group participated only in their regular daily rowing training. Prior to the initiation and at the completion of the 6 week IMT program, on three separate occasions both groups underwent: a) an incremental rowing ergometer test (Concept IIc, Nottingham, UK) b) a rowing ergometer 2000m all-out effort and c) a rowing ergometer 5 minute all-out effort without prior warm-up. Lung function was measured at rest. RESULTS: Six weeks of IMT significantly (p<0.05) increased PImaxfrom (Mean ± SEM) 93.1±7.3 to 143.2±6.9 (cmH20), FEF25 from 5.54±0.8 to 7.1±1.5 (L.sec-1), MVV from 146.5±17.5 to 164.0±16.0 (L.min-1), FEV1 from 4.06±0.4 to 4.92±0.41 (L), FVC from 4.53±0.2 to 5.0±0.2 (L), VCin from 4.32±0.5 to 4.61±0.3 (L), VEmax from 124.5±2.5 to 134.0±6.0 (L.min-1) and decreased Dimax from 0.89±0.1 to 0.84±0.1. IMT also increased Sa, O2 from 87.0±2.6 to 91.0±1.5 (%) and Powerav from218.3±13.1 to 231.0±17.9 (W), and reduced Di from 1.08±0.1 to 1.03±0.1, rowing time from 487.4±11.5 to 461.4±22.87 (sec) during the 2000m all-out effort in the T group. Moreover, IMT significantly (p<0.05) increased rowing distance from 1285.3±17.1 to 1319.6±21.2 (m) during the 5 minute all-out effort without prior warm-up in the T group. In contrast, no changes in PImax or any other parameter were observed in the C group during the six week period. CONCLUSIONS: We conclude that six weeks of IMT increases Sa, O2 and rowing performance in highly trained female rowers that exhibit severe EIAH.