title: Acute cardio-respiratory changes induced by hyperpnoea using a respiratory muscle trainer.
abstract: The aim of this study was to examine the cardio-respiratory effects of voluntary hyperpnoea using a respiratory muscle trainer (RMT) with three different sized rebreathing bags. In particular, the effects of hyperpnoea on inspired and end-tidal gas concentrations were determined. Seven adult males completed three 30 min bouts of hyperpnoea using optimal, oversized and undersized rebreathing bags. Inspired (F(I)) and expired end-tidal (F(ET)) O2 and CO2 concentrations, arterial O2 saturation (S(AO2)) and heart rate were measured during hyperpnoea. Before and after a bout of hyperpnoea, pulmonary function and blood pressure (BP) were assessed. Data were analysed using a two-way repeated-measures ANOVA, with p < 0.05 considered significant. Three subjects experienced discomfort during hyperpnoea and stopped after 20 min. During hyperpnoea, the F(ETCO2) was maintained at 4.6 +/- 0.7% irrespective of bag size. The increase in F(ICO2) over time reached 0.5 +/- 0.5% at 20 min. The F(IO2) fell to 19.4 +/- 0.8% at 20 min, and S(AO2) decreased to 97%. Heart rate and systolic BP increased slightly, but independently of rebreathing bag volume. No changes in pulmonary function or diastolic BP were found. It is concluded that the RMT maintained a constant F(ETCO2) at the expense of a mild hypoxia. The acute effects of hyperpnoea on the cardio-respiratory system are generally mild, but not always tolerable for 30 min.
authors.affiliation: School of Applied Sciences, University of Glamorgan, Pontypridd. Mid Glamorgan CF37 1DL, UK. lpassfie@glam.ac.uk
authors.forename: Louis
authors.initials: L
authors.lastname: Passfield
authors.forename: Trevor
authors.initials: T
authors.lastname: Dobbins
authors.forename: Steven
authors.initials: S
authors.lastname: Myers
authors.forename: Mike
authors.initials: M
authors.lastname: Reilly
authors.forename: E Mark
authors.initials: EM
authors.lastname: Williams
mesh_terms: D000328:Adult; D001794:Blood Pressure; D001945:Breathing Exercises / Q000009:adverse effects*; D006339:Heart Rate; D006801:Humans; D006985:Hyperventilation / Q000209:etiology* / Q000503:physiopathology*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010100:Oxygen / Q000097:blood; D011659:Pulmonary Gas Exchange; D012132:Respiratory Muscles / Q000502:physiology*; D013997:Time Factors
chemical_list: D019344:Lactic Acid; D010100:Oxygen