Power Versus Sarcopenia: Associations with Functionality and Physical Performance Measures

Background/objective: While assessment of sarcopenia has drawn much attention, assessment of low muscle power has not been studied widely. This is, to a large extend, due to a more difficult assessment of power in practice. We aimed to compare the associations of low power and sarcopenia with functional and performance measures.

Material And Methods: We designed a retrospective and cross-sectional study. Community-dwelling outpatient older adults applied to a university hospital between 2012 and 2020 composed the population. We estimated body composition by bioimpedance analysis. Other measures were handgrip strength, timed-up-and-go-test (TUG), usual gait speed (UGS), activities of daily living (ADL) and instrumental activities of daily living (IADL) tests. We assessed muscle power by a practical equation using a 5-repetition sit-to-stand power test. We adjusted the power by body weight and defined low muscle power threshold as the lowest sex-specific tertile. We noted demographic characteristics, number of medications, and diseases. We defined sarcopenia by EWGSOP2 definition.

Results: Cut points for low relative muscle power were <2.684 and <1.962 W/kg in males and females, respectively. Low muscle power was related with both measures of disability (impaired ADL and IADL) (OR=2.4, 95% CI= 1.4-4.0, p=0.001; OR=2.4, 95% CI= 1.4-4.1, p=0.001; respectively). Low muscle strength (i.e. probable sarcopenia) was only related with disability in IADL (OR=3.6, 95% CI= 1.6-8.; p=0.002); confirmed sarcopenia was related with neither measures. Low muscle power was not related with impaired TUG (p=1) but with impaired UGS (OR=6.6, 95% CI= 3.6-11.0; p<0.001). Probable sarcopenia was not related with impaired TUG (p=0.08) but with impaired UGS (OR=2.4, 95% CI= 1.1-5.3; p=0.03) and confirmed sarcopenia was related with neither measures (p=1, p=0.3; respectively).

Conclusion: Low muscle power detected by simple and practically applicable CSST (Chair Sit To-Stand Test) power test was a convenient measure associated with functional and performance measures. It was related to functionality and performance measures more than sarcopenia. Future longitudinal studies are needed to examine whether it predicts future impairment in ADL, IADL, and performance measures.