Acute cardio-respiratory changes induced by hyperpnoea using a respiratory muscle trainer

Area of Science:

• Exercise Physiology
• Respiratory Physiology

Background:

• Voluntary hyperpnoea is a breathing exercise.
• Respiratory muscle trainers (RMTs) are used to improve respiratory function.
• The impact of different rebreathing bag sizes on hyperpnoea's effects is not well understood.

Purpose of the Study:

• To investigate the cardio-respiratory effects of voluntary hyperpnoea using an RMT.
• To determine the influence of varying rebreathing bag sizes on inspired and end-tidal gas concentrations during hyperpnoea.

Main Methods:

• Seven adult males performed 30-minute hyperpnoea sessions with RMTs using optimal, oversized, and undersized rebreathing bags.
• Measurements included inspired (F(I)) and end-tidal (F(ET)) O2 and CO2, arterial O2 saturation (S(AO2)), heart rate, pulmonary function, and blood pressure (BP).
• Statistical analysis used a two-way repeated-measures ANOVA.

Main Results:

• End-tidal CO2 (F(ETCO2)) was maintained at approximately 4.6% regardless of bag size.
• Inspired O2 (F(IO2)) decreased to 19.4% and S(AO2) to 97% at 20 minutes, indicating mild hypoxia.
• Heart rate and systolic BP increased slightly, while pulmonary function and diastolic BP remained unchanged.
• Three participants experienced discomfort and ceased the 20-minute mark.

Conclusions:

• Respiratory muscle training maintained stable end-tidal CO2 at the cost of mild hypoxia.
• The acute cardio-respiratory impact of hyperpnoea is generally mild.
• Hyperpnoea sessions of 30 minutes may not be tolerated by all individuals due to discomfort.