Inspiratory muscle training for asthma – A randomized controlled pilot study

Background: The objective of a treatment for asthma is to achieve and maintain control of the disease for long periods. Inspiratory muscle training (IMT) appears as an alternative in care of patients with asthma, being used as a complementary treatment to the pharmacological one. Objectives: To investigate the effects of IMT on respiratory muscle strength and functional capacity in healthy and asthmatics adults. Methods: We performed a randomized controlled trial with blinding of outcome assessment. Twenty individuals healthy and asthmatics were randomly divided into four groups: experimental asthmatics (EA), experimental healthy (EH), control asthmatics (CA) and control healthy (CH). Spirometry, maximal inspiratory pressure (MIP) and distance walked during six minutes (6MWD) were measured before and after the six weeks of study. Participants performed 30 breaths, using a pressure threshold inspiratory muscle trainer (POWERbreathe®), twice a day, five days/week, for six weeks. Experimental group trained at 50% MIP and control group at 15% MIP. Training intensity was adjusted once a week. Results: EA, EH and CH groups demonstrated significant improves in MIP ( P <0,05): EA (89,8 ± 24,2 cmH 2 O to 136,4 ± 22,5 cmH 2 O), EH (84,0 ± 25,5 cmH 2 O to 124,5 ± 26,8 cmH 2 O) and CH (96,6 ± 24,2 cmH 2 O to 123,6 ± 29,6 cmH 2 O ) . 6MWD increases in EA (648,2 to 693,4 m; P <0,05) and CA (599,8 to 626,3 m; P <0,05) groups. Conclusion: IMT promoted clinical improvements in all groups, especially the asthmatic experimental group, being an important non-pharmacological option for people with asthma.