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

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 cmH 2 O] 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 cmH 2 O, and for MEP ranged from 19 to 22.5 cmH 2 O. 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.