Demographic data are presented as mean ± standard deviation. Intra- and inter-rater reliabilities were evaluated using the intraclass correlation coefficient (ICC) with 95% confidence interval (CI). Intra-rater reliability was determined using ICC(1,1) and ICC(1,3) methods.12 (link)) Subsequently, inter-rater reliability was determined using the ICC(2,1) and ICC(2,3) methods.12 (link)) ICC values were interpreted according to the following: <0.5, poor reliability; 0.5–0.75, moderate reliability; 0.75–0.90, good reliability; >0.90, excellent reliability.13 (link))The concurrent validity of the quadriceps muscle thickness was examined by calculating Spearman’s correlation coefficient for comparisons of quadriceps muscle thickness with muscle strength, leg SMI assessed by BIA, and calf circumference. In addition, because the quadriceps muscle thickness is represented by a one-dimensional unit (length), we also compared quadriceps muscle thickness squared with muscle strength to match the unit dimensions. We also investigated the relationship between leg SMI and calf circumference by calculating Spearman’s correlation coefficient. The sample size was calculated based on a previous study and unpublished data. We determined a minimum acceptable reliability level of 0.70 and an expected minimum acceptable reliability level of 0.90 for the three different raters. A type I error rate of 0.05 and 90% power were assumed (n=20). Statistical significance was set at P<0.05. Statistical analyses were performed using R software (R Foundation for Statistical Computing, Vienna, Austria).