Bailey, S. J., Romer, L. M., Wilkerson, D. P., DiMenna, F. J., & Jones, A. M. (2010). Influence of inspiratory muscle training on pulmonary O2 uptake kinetics and exercise tolerance in humans. Presentation 848 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

"Interventions that increase muscle oxygen delivery during exercise have been associated with faster ‘overall’ O2 uptake response dynamics and an improved tolerance of intense exercise. Significant respiratory muscle fatigue is observed during intense (>80% of VO2max) exercise and it has been suggested that this might limit O2 delivery to the locomotory muscles. A period of inspiratory muscle training has been demonstrated to reduce respiratory muscle fatigue and to improve cycle exercise performance; however, the influence of IMT on VO2 dynamics has yet to be investigated."

This study determined whether inspiratory muscle training improves exercise tolerance through effects on VO2 dynamics. Recreationally-active Ss (N = 12) were allocated to receive four weeks of either pressure threshold inspiratory muscle training (30 breaths twice daily against a resistance of ~50% of the maximum inspiratory pressure) or ineffective training (60 breaths once daily against a fixed resistance of ~15% of the inspiratory muscle training). Ss completed severe-intensity step-cycle exercise transitions before and after the four-week intervention period to determine pulmonary VO2 kinetics and exercise tolerance.

Maximum inspiratory pressure was significantly increased following inspiratory muscle training but not in the ineffective training treatment. Overall pulmonary VO2 kinetics were only speeded following inspiratory muscle training consequent to an increased VO2 fast component amplitude and reduced VO2 slow component amplitude. Exercise tolerance was improved by 39% following inspiratory muscle training but was not altered following ineffective training.

Implication. Four weeks of inspiratory muscle training increased inspiratory muscle strength, resulted in faster overall VO2 kinetics, and improved severe exercise tolerance in healthy individuals.

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