Author(s): LORENZO, I., SERRA-PRAT, M., MUR-GIMENO, E., GUIRAO, L.L., YEBENES, J.C., Institution: CONSORCI SANITARI DEL MARESME, Country: SPAIN, Abstract-ID: 655

INTRODUCTION:
Muscle function is regulated by multiple hydroelectrolytic mechanisms that modulate cel-lular volume and extend beyond isolated plasma electrolyte concentrations. In particular, cellular hydration status and membrane-related properties are critical for muscle contrac-tility and functional performance. However, the contribution of integrated hydration and electrolyte regulation profiles to muscle function in older adults remains insufficiently understood. Objective: To identify which physiological domains of hydroelectrolytic reg-ulation are most strongly associated with muscle strength and functional performance in community-dwelling older adults
METHODS:
A cross-sectional study was conducted in 96 community-dwelling individuals aged ≥70 years. Markers of cellular hydration and membrane integrity were assessed using bioelec-trical impedance analysis, together with plasma and urinary sodium and chloride con-centrations. Principal component analysis (PCA) was applied to identify integrated phys-iological patterns of hydroelectrolytic regulation. Associations between these patterns and muscle strength (handgrip) and functional performance (Timed Up and Go test) were ex-amined, adjusting for sex and fat-free mass
RESULTS:
Three principal components describing distinct domains of hydroelectrolytic regulation were identified. The first component (F1) reflected an integrated renal–cellular pattern linking urinary sodium and chloride excretion with markers of cellular hydration. The second component (F2) was predominantly characterized by plasma electrolyte concentra-tions, while the third component (F3) was mainly associated with cellular hydration and volume parameters. Both F1 and F3 were independently associated with greater muscle strength and better functional performance, whereas F2 showed no independent associa-tion
CONCLUSION:
Integrated hydroelectrolytic regulation profiles related to cellular hydration—either com-bined with renal electrolyte excretion or predominantly intracellular—were independently associated with muscle strength and functional performance in older adults. In contrast, plasma electrolyte concentrations alone were not independently associated, underscoring the relevance of multidimensional hydration assessment beyond isolated biochemical markers.