Comparison of inspiratory muscle strength training effects between older subjects with and without chronic obstructive pulmonary disease.

BACKGROUND/PURPOSE: Inspiratory muscle strength training (IMST) has been traditionally recommended for patients with chronic obstructive pulmonary disease (COPD) to improve respiratory strength. Respiratory strength is reduced as age increases. However, few studies have focused on the effects of IMST on older adults without COPD.

METHODS: Subjects were divided into training non-COPD (TNC, n = 24) and training COPD (TC, n = 12) according to their forced expiratory volume in 1 second (% predicted). Both groups received 6 weeks of IMST, with training at 75-80% of maximal inspiratory pressure using pressure threshold trainers. A second group of COPD subjects served as controls (CC, n = 24), which received no training. Dyspnea was measured using the basic dyspnea index. Health-related quality of life was measured using the SF-36. The SF-36 subcategories, physical component summary and mental component summary were compared. A 6-minute walk test was performed to determine functional status. Two-way repeated measures analysis of variance was used to compare group effects and training effects of IMST.

RESULTS: Maximal inspiratory pressure was increased in both training groups (TNC: 59.1 cmH(2)O pre-IMST to 82.5 cmH(2)O post-IMST; TC: 53.2 to 72.6), but not in the CC group. Therefore, the basic dyspnea index was improved in both training groups (TNC: 9.6 to 10.8; TC: 6.2 to 7.3). Functional status was improved in the TNC group (TNC: 392.1 m to 436.3 m), but not in the TC or CC groups. Quality of life was improved in the physical component summary in both training groups.

CONCLUSION: IMST increases maximal inspiratory pressure, relieves dyspnea and improves health-related quality of life in older adults. IMST especially improves functional status in subjects without COPD. IMST benefits subjects with COPD and those without COPD. Therefore, IMST as a treatment tool is not confined to patients with COPD.