Abstract
Aim/background: To investigate sex-specific associations of upper and lower limb muscle strength, mass, and quality derived from handgrip strength (HGS) and 30-s chair stand test (CST), with physical performance in older adults.
Methods: Cross-sectional study (n = 454, 65.9 ± 4.9 years, 74.2% females). The proxies of upper and lower limb strength were HGS and 30-s CST, respectively. Muscle mass was measured by dual-energy X-ray absorptiometry. Muscle quality was determined as: (a) HGS/arm muscle mass and (b) 30-s CST/leg muscle mass. Physical performance: 6-min walk test (6MWT), timed up and go (TUG), maximum gait speed, and Berg Balance Scale. Multiple linear regression and receiver operating characteristic curves were used for data analyses.
Results: For females, upper limb strength showed positive associations with all physical performance tests, as exemplified by the 6MWT (β = 3.85, 95% CI [2.32, 5.39]), TUG (β = -0.03, 95% CI [-0.06, -0.01]), maximum gait speed (β = 0.01, 95% CI [0.01, 0.02]), and Berg Balance Scale (β = 0.13, 95% CI [0.03, 0.22]). Lower limb strength, 6MWT (β = 7.68, 95% CI [5.60, 9.75]), was also positively associated with these tests, Further, lower limb muscle mass was positively associated with 6MWT (β = 17.38, 95% CI [5.80, 28.95]) and maximum gait speed (β = 0.08, 95% CI [0.02, 0.13]), while lower limb muscle quality showed associations with 6MWT (β = 3.64, 95% CI [0.48, 6.81]). In males, lower limb strength was associated with TUG (β = -0.09, 95% CI [-0.14, -0.05]) and Berg Balance Scale (β = 0.17, 95% CI [0.03, 0.30]), while upper limb strength and mass were associated with 6MWT (β = 2.39, 95% CI [0.28, 4.49]; β = 8.63, 95% CI [4.19, 13.07], respectively). Lower limb muscle quality was associated with 6MWT (β = 46.61, 95% CI [24.05, 69.17]) and TUG (β = -0.80, 95% CI [-1.21, -0.40]). CST-based muscle strength and quality better determined older adults with low physical performance.
Conclusion: In older adults, CST-based strength and quality demonstrated stronger and more consistent associations with physical performance than HGS-based metrics, regardless of sex. Muscle mass was found to be limited for this purpose. Therefore, CST-based muscle strength and quality seem to be more clinically useful compared with HGS-based metrics in identifying older adults at an increased risk of impaired physical performance. Significance/Implications: CST-based muscle strength and quality appear to be more clinically useful than HGS-based metrics for identifying older adults at risk of impaired physical performance.