Effects of inspiratory muscle training on physical performance during backpack carrying

Abstract

Purpose: Restricting chest movement when carrying a loaded backpack reduces efficiency and increases the work of the respiratory muscles. The aim of the present study was to investigate the effects of six weeks of inspiratory muscle training (IMT) on respiratory muscle strength and endurance and on physical performance when carrying a load. Methods: Twenty male (age: 32.2 ± 3.4 years) members of the Special Operations Unit of the Slovenian Army volunteered to participate. The experimental group (n=10) trained their respiratory muscles for six weeks against an incremental inspiratory resistance with a breathing apparatus. The placebo group (n=10) performed the same IMT protocol but with a sham inspiratory resistance. Assessment of the subjects before and after IMT included measurements of the maximal inspiratory and expiratory pressures, heart rate measurements, and ratings of perceived physical and respiratory exertion before and after a 60-min walk test with a 25-kg backpack. Results: After six weeks of IMT, the maximum inspiratory pressure measured before and after the 60-minute walk test increased significantly (p < 0.001) in the experimental group by 47 ± 13% and 58 ± 20%, respectively. Inspiratory fatigue was also significantly lower in the experimental group. No changes were observed in the heart rate and the rating of perceived exertion during the walking test. In the placebo group, no significant changes were observed in the measured parameters after IMT.Conclusion: Six weeks of IMT with progressive breathing resistance improves strength and reduces fatigue of the respiratory muscles. Individuals who perform tasks that require them to carry a heavy backpack for extended periods of time may benefit from IMT.