A New Protocol for Evaluating Maximum Respiratory Pressures in Individuals With Multiple Sclerosis: Concurrent Validity and Test-Retest Reliability.

Abstract

Background and purpose There is a need for new and inexpensive methods for the maximum inspiratory and expiratory pressures (MIP/MEP) test. The one-repetition maximum (1RM) test is an easy and cost-effective method to measure maximal strength. The purpose of this study was to validate a MIP/MEP test protocol based on the 1RM test, its test-retest reliability, and minimal detectable change (MDC) in individuals with multiple sclerosis. Methods Fifty-two individuals (53.6 ± 10 years; 5.7 ± 1.8 points on Expanded Disability Status Scale) (46% relapsing-remitting; 23% primary progressive; 31% secondary progressive) attended two appointments 7 to 10 days apart. MIP/MEP tests were performed using a threshold valve device (1RM-based protocol) and a digital manometer (reference test). The 1RM-based protocol included an incremental phase (load increase [30 cmH2O] to achieve task failure) and a halving phase (load halfway between the lowest failed attempt and the last valid attempt was prescribed). Results The concurrent validity of the 1RM-based protocol was good to excellent with respect to the reference test (MIP: day 1, n = 49, intraclass correlation coefficient [ICC (95% confidence intervals)] = 0.87 (0.78-0.93); day 2, n = 48, ICC = 0.91 (0.82-0.95); MEP: day 1, n = 49, ICC = 0.82 (0.60-0.91); day 2, n = 49, ICC = 0.88 (0.64-0.95)). The test-retest reliability was good for MIP [n = 46, ICC = 0.88 (0.79-0.93)] and excellent for MEP [n = 48, ICC = 0.90 (0.83-0.94)]. The MDC(90-95) for MIP ranged from 23.7 to 28.2 cmH2O, and for MEP ranged from 19 to 22.5 cmH2O. Discussion and conclusion This study validated a new 1RM-based protocol for the MIP/MEP tests using a respiratory muscle training threshold valve device in individuals with multiple sclerosis, showing good to excellent concurrent validity compared with the reference test, as well as good to excellent test-retest reliability. The MDC reported can be interpreted and applied in the clinical setting.