Independent and combined associations of cardiorespiratory fitness and muscle strength with metabolic syndrome in older adults: A cross-sectional study

Background: Studies have shown that low cardiorespiratory fitness (CRF) and low muscle strength are independently associated with metabolic syndrome (MetS) in older adults. This study investigated the isolated and combined associations of low CRF and muscle strength with MetS in older adults. Methods: This cross-sectional study included 184 older adults (71% women; aged 65.6 +/- 4.3 years) without a prior history of cardiovascular disease. CRF and muscle strength were assessed by the six-minute walking test and 30-s chair stand test, respectively. Results below the 25th percentile of the cohort were used to define low CRF and low muscle strength. MetS was defined according to NCEP-ATP III criteria. Poisson's regression with robust variance was used to determine the prevalence ratio (PR) for MetS. Reference group was composed by older adults with both CRF and muscle strength above 25th percentile. Results: Prevalence of low CRF, low muscle strength, and combined low CRF and muscle strength was 22.8%, 17.9%, and 10.9%, respectively. The prevalence of MetS was 56.5% in the full cohort. Isolated low CRF (PR 1.05, 95% CI 0.73 to 1.52; p = 0.793) and muscle strength (PR 1.09, 95% CI 0.74 to 1.61; p = 0.651) were not associated with MetS in the adjusted analysis. Combined low CRF and muscle strength was associated with MetS (PR 1.45, 95% CI 1.09 to 1.93; p = 0.011). Conclusions: Older adults with combined, but not isolated, low CRF and muscle strength showed an increased risk for MetS.