*4.4. Statistical Analysis*

Agreements between biopsy and MuscleSound® estimated fuel level scores were assessed by 95% intra-class correlation based on a one-way, consistency model [33]. Pearson's correlations were used to determine the association between site-specific measurements. The muscle glycogen concentration across the different states was assessed using a general linear mixed model (LMM) using the R package lme4 (R Foundation for Statistical Computing, Vienna, Austria). All models included a random intercept for subject to adjust for baseline levels and inter-individual homogeneity. Additionally, creatine dry weight was included as a covariate in all models. Each model was estimated using restricted maximum likelihood, with the tests for statistical significance of the fixed effects performed using type II Wald tests with Kenward–Roger degrees of freedom. Where significant fixed effects were evident, Tukey's post hoc comparisons were performed to detect specfic condition differences.
