Influence of subcutaneous adipose thickness and dominance on reliability of quadriceps muscle quality in healthy young individuals

Abstract

Background: Echo intensity (EI) can be useful to check muscle quality and has been widely used to identify tissue damage. In the clinical and sports context, it has been used to identify metabolic disorders and training muscle performance.

Objective: To determine whether subcutaneous adipose thickness (SAT) influences the inter-session EI reliability of the quadriceps femoris and whether EI is influenced by dominance in young healthy subjects.

Design: All procedures were approved by the local Institutional Research Ethics Committee (project number 2.620.204). This is a cross-sectional study where 19 healthy young individuals volunteered.

Method: The individuals were assessed at two time points by an experienced examiner. Imaging of the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) muscles were performed bilaterally by ultrasonography. EI and SAT analysis was performed using ImageJ^®software.

Results/findings: Inter-session intraclass correlation coefficient (ICC) for EI_measured showed moderate reliability for RF (R = 0.578; P = 0.038) and VL (R = 0.735; P = 0.004) and low for VM (R = 0.402; P = 0.142). When corrected by SAT, inter-session (EI_corrected), ICC values showed good reliability for RF (R = 0.826; P < 0.001) and VM (R = 0.765; P = 0.002) and excellent for VL (R = 0.909; P < 0.001). Considering inter-side reliability, Student's paired t-test demonstrated no difference for EI_measured (P > 0.283), EI_corrected (P > 0.127), and SAT (P > 0.356).

Conclusions: SAT influenced the inter-session reliability values of EI in all muscles evaluated. Although they showed similarity, EI values were not influenced by dominance in young healthy subjects.

Keywords: Intramuscular fat; Muscle quality; Muscle ultrasound; Quadriceps femoris.