Skeletal muscle mass was assessed with a single-slice CT scan (SOMATOM Definition Flash, Siemens, München, Germany [MUMC+ and JBZ]; or Ingenuity CT, Philips Medical Systems, Eindhoven, The Netherlands [MMC]) to determine the anatomic cross-sectional area (CSA) of the quadriceps muscle, as described previously (22 (link)). A single-slice image was made 15 cm proximal to the top of the patella of both legs. Quadriceps muscle CSA of the dominant leg was calculated by manual tracing using ImageJ software (version 1.52p; National Institutes of Health, Bethesda, MD).