Introduction: Sarcopenia affects over 20% of adults aged 65+, increasing the risk of falls, disability, and death. While current definitions rely on muscle strength loss, evidence suggests that muscle power declines earlier and is a stronger predictor of adverse outcomes, warranting its consideration as a key diagnostic criterion. Hence, the present study compared sex-specific associations between sarcopenia indexes operationalized according to lower-limb muscle strength and power and the occurrence of negative events in older adults with mobility limitations.

Methods: This is a prospective study. Data on older adults (70+ years) with mobility limitations (SPPB scores ranging from 3 to 9) from 11 European countries were analyzed. Sarcopenia was operationalized according to the Short Physical Performance Battery (SPPB). Muscle power measures were estimated according to the results of the 5-time sit-to-stand (5STS) test using validated equations. Then, four sarcopenia indexes were created by replacing the 5STS test results with muscle power measures. The outcomes were assessed after 24 months of randomization and included mobility disability, hospitalization, and death.

Results: Data from 1,422 participants were analyzed. Cox regression models revealed sex-specific associations between sarcopenia indexes and adverse outcomes. Sarcopenia indexes incorporating muscle strength or power were significantly associated with mobility disability in both sexes, and with hospitalization and death in women. According to Akaike’s Information Criterion, sarcopenia indexes based on muscle power showed the strongest associations with negative outcomes.

Conclusions: Sex-specific associations exist between modified sarcopenia indexes and adverse outcomes in older adults with mobility limitations. Notably, sarcopenia operationalizations incorporating muscle power measures demonstrated stronger associations with adverse outcomes in comparison to traditional diagnosis methods.