Impact of high-intensity interval hyperpnea on aerobic energy release and inspiratory muscle fatigue

Respiratory muscle endurance training reportedly has beneficial effects on whole-body endurance performance. We produced a novel high-intensity interval (HII) protocol and characterized the associated physiological responses and respiratory muscle fatigue. Peak oxygen uptake of respiratory muscle (VO2peakRM) was estimated during the respiratory incremental test. The HII session consisted of five 3-minute hyperpnea periods at 100% VO2peakRM interspersed with 2-minute periods at 40%VO2peakRM (25 min total). The high-intensity continuous (HIC) session involved a single time-to-end bout of hyperpnea at 100%VO2peakRM. The moderate-intensity continuous (MIC) session involved 25 min of hyperpnea at 60% of maximal voluntary ventilation. VO2RM was recorded continuously, and maximal inspiratory pressure (PImax) was assessed before and after the sessions. HII session: VO2RM gradually increased as the sets proceeded, whereas PImax decreased significantly. HIC session: VO2RM increased progressively, and the time to end was 6.5 +/- 0.5 min. PImax decreased significantly. MIC session: VO2RM did not change for 25 min, and PImax remained unchanged. The duration of VO2RM at nearand supra-maximal levels in the HII session (10 +/- 1 min) was longer than that in the HIC session (4 +/- 1 min). The decrease in PImax was larger in the HII session (-12 +/- 3 %) than MIC session (-4 +/- 3 %). The HII protocol is characterized by a longer time to maximally stimulate the aerobic energy system of respiratory muscle than the HIC protocol and greater inspiratory muscle fatigue than the traditional MIC protocol. These results suggest that the HII protocol could enhance the efficacy of respiratory muscle training programs.

Automated summary

Respiratory muscle endurance training has beneficial effects on whole-body endurance performance. A novel high-intensity interval (HII) protocol is found to enhance the efficacy of respiratory muscle training programs.