Respiratory Muscle Force, Body Position, and Sarcopenic Indices: Correlations and Clinical Implications in Older Women

BACKGROUND: Risk factors for aspiration pneumonia in aged adults include respiratory muscle weakness and ineffective coughing, which might be influenced by physical position and be associated with sarcopenia. OBJECTIVES: This investigation sought to elucidate the optimal physical position for maximising respiratory muscle force and cough effectiveness, to investigate correlations between respiratory muscle force and other sarcopenia-related parameters in older people, which remain largely unclear, and to search for a novel pneumonia prevention approach. METHODS: Twenty-six healthy older women were evaluated in six positions: supine (0°), 30° semi-recumbent, 60° semi-recumbent, 90° sitting, and 60° semi-recumbent with left/right trunk rotation. Maximum inspiratory and expiratory pressures, cough peak flow, respiratory function, tongue pressure, and self-assessed cough ease were measured. We analysed correlations between respiratory muscle force and other parameters. RESULTS: The 60° semi-recumbent position demonstrated significantly greater maximum inspiratory pressure, expiratory pressure, cough peak flow, and peak expiratory flow than supine and rotated positions. This position was rated subjectively easiest for coughing. Respiratory muscle strength showed moderate correlations with sarcopenia-related indices. Inspiratory muscle strength correlated with % predicted value forced vital capacity (%FVC; r = 0.509), quadriceps strength (r = 0.502), cough peak flow (r = 0.420), and handgrip strength (r = 0.371). CONCLUSIONS: The 60° semi-recumbent position optimised respiratory muscle force and cough effectiveness in older women, suggesting clinical implications for aspiration pneumonia prevention strategies. The link between respiratory and limb muscle indices possibly supported the concept of sarcopenia in respiratory muscles, suggesting its integration into approaches to pneumonia prevention and management.