The effect of moderate- and high-intensity inspiratory muscle training on inspiratory muscle strength and aerobic capacity in healthy adults
Date of Award
Fall 11-14-2024
Document Type
Dissertation
Degree Name
Doctor of Kinesiology (PhD)
Department
Kinesiology
First Advisor
Joshua Smith
Second Advisor
Andrew Alexander
Third Advisor
Aaron Aslakson
Abstract
Introduction: Previous research has demonstrated that moderate-intensity inspiratory muscle training (IMT) improves maximal inspiratory pressure (MIP) and exercise tolerance and performance in athletes, but the effects of high-intensity IMT on MIP in healthy adults has not been determined. The purpose of this study was to compare to the effects of high- and moderate-intensity IMT on MIP and aerobic capacity in healthy adults.
Methods: 26 healthy adults were enrolled in this eight-week randomized controlled trial. Participants completed MIP and VO2max testing prior to being randomized into a moderate- or high-intensity intervention group. Participants in both groups performed IMT to 40 repetitions or until task failure once per day, five times per week, for eight weeks. IMT intensity for the moderate-intensity group was 50% of pre-training MIP and 80% of pre-training MIP for the high-intensity group. MIP and VO2max testing were performed again at the end of the eight-week trial. Participants and outcomes assessors were blinded to participant group allocation. Repeated measures ANOVA was used to assess difference of pre- and post-training MIP and VO2max between groups.
Results: Significant increases in MIP from pre- to post-training were present for both groups (p=.001 for moderate-intensity, p<.001 for high-intensity). No significant group or interaction effects existed for MIP. There were no significant main effects for group, time, or interaction for VO2max.
Conclusion: High-intensity IMT to task-failure improves MIP but is not more effective at improving MIP than moderate-intensity IMT training.
Clinical Relevance: IMT has practical applications for athletes but can also be used as a rehabilitative tool for clinical populations with cardiac or pulmonary conditions. As IMT can 5 uncomfortable and difficult to perform at high-intensities, performance of training at moderate-intensities may help with tolerance and adherence to training protocols while providing equivalent outcomes to high-intensity training. Further exploration of optimal IMT prescription individualized protocols should be explored to continue optimizing outcomes.