Manual Testing of Respiratory Muscles in Adults with Asthma: An Intra-and Interrater Reliability and Validity Study

Background: Manual Muscle Testing (mmt) is a valuable tool for evaluating ventilatory mechanics in adults with asthma. However, there is limited literature reporting the psychometric properties of this test. This study aimed to assess the reliability and validity of mmt in evaluating respiratory muscles in adults with asthma. Methods: A validity study of diagnostic tests was conducted. Measurements were performed by two randomly assigned independent evaluators. Variables included muscle strength (measured by mmt and static respiratory pressures), as well as sociodemographic, anthropometric, and disease related factors. mmt reliability was assessed using weighted kappa. Convergent validity was analyzed by comparing mmt and respiratory pressure measurements using Pearson’s correlation coefficient. A significance level of p < 0.05 was considered. Results: Twenty-six adults with stable asthma participated in the study. Intrarater reliability for mmt ranged from moderate to substantial (kappa = 0.45–0.88) across all evaluated muscles. Interrater reliability for the intercostal muscles ranged from slight to fair (kappa = 0.07–0.24) and from fair to substantial (kappa = 0.36–0.75) for other muscles. The convergent validity between mmt and respiratory pressures was low (r = 0.20–0.48). Conclusions: mmt is a reliable tool for assessing respiratory muscle strength in adults with asthma. This study supports the use of mmt in clinical settings for respiratory muscles, particularly when more objective measures, such as mip and mep, are unavailable.