Respiratory Muscle Strength in Hypertensive Adults: Age- and Sex-Specific Reference Values for a Brazilian Population

Background/Objectives: Hypertension is a major modifiable risk factor for cardiovascular disease and may negatively affect muscle strength through vascular and metabolic mechanisms. Nevertheless, reference values for respiratory muscle strength (RMS) in hypertensive adults remain unavailable. This study aimed to establish sex- and age-specific reference values for maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in Brazilian adults with hypertension and to investigate clinical factors associated with these measures. Methods: This cross-sectional study included 234 hypertensive adults (109 women and 125 men; 30–80 years) enrolled in a cardiovascular rehabilitation program. Anthropometric, hemodynamic, and clinical data were collected. RMS was assessed using standardized procedures for MIP and MEP with an analog manovacuometer (−300 to +300 cmH2O). Participants were stratified by age and sex. Statistical analyses included the Mann–Whitney U and Kruskal–Wallis tests and multivariate linear regression (p < 0.05). Results: Men exhibited significantly higher MIP and MEP values than women across most age groups. RMS declined progressively with age, with a more marked reduction after 60 years. MIP was identified as the primary predictor of MEP in both sexes, with higher coefficients of determination in men. The reference values obtained were largely comparable to those reported for healthy individuals. Conclusions: This study provides clinically relevant reference values for RMS Brazilian individuals with hypertension, offering useful parameters for respiratory assessment and individualized rehabilitation strategies.