Assessment of maximum inspiratory pressure - Prior submaximal respiratory muscle activity ('warm-up') enhances maximum inspiratory activity and attenuates the learning effect of repeated measurement

Background: The variability of maximal inspiratory pressure (PImax) in resp onse to repeated measurement affects its reliability; published studies hav e used between three and twenty PImax measurements on a single occasion. Ob jective: This study investigated the influence of a specific respiratory 'w arm-up' upon the repeated measurement of inspiratory muscle strength and at tempts to establish a procedure by which PImax can be assessed with maximum reliability using the smallest number of manoeuvres. Methods: Fourteen hea lthy subjects, familiar with the Mueller manoeuvre, were studied. The influ ence of repeated testing on a single occasion was assessed using an 18-meas urement protocol. Using a randomised cross-over design, subjects performed the protocol, preceded by a specific respiratory warm-up (RWU) and on anoth er occasion, without any preliminary activity (control). Comparisons were m ade amongst 'baseline' (best of the first 3 measurements), 'short' series ( best of 7th to 9th measurement) and 'long' series (best of the last 3 measu rements). Results: Under control conditions, the mean increase ('baseline' vs. 'long' series) was 11.4 (5.8)%; following the RWU, the increase (post R WU 'baseline' vs. 'long' series) was 3.2 (10.0)%. There were statistically significant differences between measurements made at all 3 protocol stages ('baseline', 'short' and 'long' series) under control conditions, but none following the RWU. Conclusions: The present data suggest that a specific RW U may attenuate the 'learning effect' during repeated PImax measurements, w hich is one of the main contributors of the test variability. The use of a RWU may provide a means of obtaining reliable values of PImax following jus t 3 measurements. Copyright(C)2001 S. Karger AG,Basel.