Assessment of Medial Gastrocnemius Thickness and Stiffness in Children with Obesity Using Shear Wave Elastography

Objectives: This study aimed to compare medial gastrocnemius (MG) muscle thickness and shear wave elastography-derived stiffness between children with obesity and healthy-weight controls and to examine associations with metabolic risk parameters. Methods: This cross-sectional study with prospective data collection included 92 children and adolescents, comprising 56 participants with obesity and 36 healthy-weight controls. Anthropometric, laboratory, and metabolic parameters were recorded. MG thickness and stiffness were assessed using standardized ultrasonography and shear wave elastography (SWE) protocols. Between-group comparisons were performed using the independent-samples t test or Mann–Whitney U test, as appropriate. Associations with metabolic parameters were evaluated using Pearson or Spearman correlation analysis, followed by partial correlation analysis adjusted for age, sex, and pubertal stage. Results: Children with obesity had lower MG stiffness than healthy-weight controls (16.80 ± 3.31 vs. 20.26 ± 3.02 kPa; p < 0.001) and greater MG thickness (2.37 ± 0.40 vs. 1.84 ± 0.38 cm; p = 0.023). After adjustment for age, sex, and pubertal stage, lower MG stiffness remained associated with higher BMI z-score (rp = −0.345, p = 0.001), waist circumference z-score (rp = −0.400, p < 0.001), WHtR z-score (rp = −0.359, p = 0.001), fasting insulin (rp = −0.296, p = 0.005), and HOMA-IR (rp = −0.315, p = 0.003). Conclusions: These findings indicate that SWE may add information to conventional ultrasonography when evaluating obesity-related alterations in skeletal muscle mechanical properties.