Muscle measurements in daily clinical practice: correlations between ultrasound, bioelectrical impedance analysis and hand grip strength

Objectives: Muscle ultrasound is gaining importance as a measurement tool to evaluate sarcopenia in daily clinical practice. This study sought to collect reference values of the biceps brachii (BB) in healthy subjects, and to correlate them to bioelectrical impedance analysis (BIA) and hand grip strength (HGS). Methods: Ultrasound was used to measure muscle thickness (MT), cross-sectional area (CSA) and muscle stiffness (EG). Lean mass (LM), fat mass (FM) and phase angle (PhA) were measured by BIA. HGS was measured using a Jamar dynamometer. Intra-rater reliability was calculated using intraclass correlation (ICC). Correlations were investigated using Pearson correlation (PCC). Results: One-hundred-twenty-three Caucasian individuals (51 male and 72 female subjects) between 18 and 69 years old were included. ICC for ultrasound was 0.99 (CI 0.98-0.99). LM, PhA and HGS showed significant correlations with MT and CSA in the entire population (PCC>0.684). These correlations were more significant and stronger in male than in female subjects (PCC>0.419 and >0.279 resp.). Significant correlations with respect to FM and EG were seen exclusively in female subjects. Conclusion: Significant correlations were observed between parameters of muscle quantity measured by ultrasound, BIA and HGS. Intra-rater reliability was excellent. Future studies in larger populations are needed to clarify the observed gender differences.