Sex-Specific Cut-off Values for Respiratory Muscle Strength in Older Women: Screening Implications for Respiratory Sarcopenia.

BACKGROUND: To establish sex-specific cut-off values for maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) in elderly women, aiming to improve the screening of sarcopenia and to explore their implications for respiratory sarcopenia by accounting for physiological differences in muscle strength and mass. METHODS: Eighty-eight older women were assessed for respiratory muscle strength (MIP, MEP), hand grip strength (HGS), and skeletal muscle mass index (SMI). Sarcopenia was diagnosed according to the Asian Working Group for Sarcopenia consensus criteria (HGS < 18 kg; SMI < 5.7 kg/m²). Pearson correlation coefficients were calculated between respiratory muscle strength and conventional sarcopenia indicators. Receiver operating characteristic (ROC) analysis was conducted to derive optimal cut-off values for MIP and MEP. Sarcopenia prevalence was compared using three threshold strategies: -1 standard deviation (SD) and -2SD from healthy young women, and the 20th percentile from age-matched older adults. RESULTS: MIP and MEP were significantly correlated with HGS (r = 0.318 and 0.323, respectively) and SMI (r = 0.291 and 0.255, respectively). The ROC-derived cut-off values were 28.50 cmH2O for MIP (area under the receiver operating characteristic curve [AUC] = 0.81, 95% confidence interval [CI], 0.70-0.93) and 49.50 cmH2O for MEP (AUC = 0.78, 95% CI, 0.64-0.92), demonstrating acceptable diagnostic performance. These values identified a meaningful proportion of sarcopenic individuals and offered a favorable balance of sensitivity and specificity compared to traditional reference thresholds. CONCLUSION: MIP and MEP may serve as accessible and complementary indicators that support the screening of sarcopenia and provide implications for respiratory sarcopenia in elderly women. The use of sex- and age-specific cut-off values could enhance diagnostic precision and facilitate early intervention strategies for respiratory muscle decline in aging populations. TRIAL REGISTRATION: Clinical Research Information Service Identifier: KCT0009413.