Abstract
Computed tomography (CT) derived skeletal muscle area (SMA) and muscle radiodensity (SMD) reflect distinctive quantitative, qualitative characteristics of skeletal muscle. Peak jump power reflects the ability to exert force within a limited time, which has greater relationship with mobility and risk of falls. CT-based SMA and SMD may have potential as useful surrogates for muscle function. However, the association of CT-based muscle parameters, especially SMD, with peak jump power has not been investigated yet. Community-dwelling older adults enrolled in the Korean Urban Rural Elderly study from 2016 to 2018 underwent abdominal CT scans and countermovement two-legged jumping test on ground reaction force platform. SMA and SMD were measured at CT images at L3 vertebral level. Mean age of 1523 patients was 74.7 years and 65.1% was female. For peak jump force, L3SMA was stronger contributing factor than SMD (standardized beta of SMA vs. SMD = 0.16 vs. 0.08 for men; 0.12 vs. 0.05 for women; p < 0.05 for all). However, SMD was a better indicator of peak jump power compared to SMA in both sexes (standardized beta of SMD vs. SMA = 0.21 vs. 0.17 for men; 0.15 vs. 0.13 for women; p < 0.05 for all). These associations remained robust even after adjustment for age, height, weight, triglyceride, HDL cholesterol, high sensitivity C-reactive protein, and insulin resistance. One standard deviation decrease of SMD was associated with 8% elevated odds of low jump power relative to weight after adjustment for potential confounders (adjusted OR = 1.08, p < 0.001), whereas the association between SMA and low jump power was attenuated. SMD improved discrimination for individuals with low jump power when added to SMA and conventional risk factors (Area under the receiver-operating characteristics curve 0.732 to 0.750, p=0.006). SMD was an independent predictor of jump power with additive discriminatory value to SMA and conventional risk factors. Our findings suggest the potential complimentary role of SMD as muscle quality indicator beyond muscle mass as a surrogate for muscle function.
Association between echo intensity and attenuation of skeletal muscle in young and older adults: a comparison between ultrasonography and computed tomography
