Detection of Muscle Quality in Children - Protocol for a Validation Study

The goal of this observational study is to evaluate the validity and reliability of ultrasound echo intensity (EI) as a diagnostic tool for assessing muscle quality in children aged 10-14 years, including normal-weight, obese, and trained young athletes. The main questions it aims to answer are: Can EI reliably and accurately measure muscle quality in children when validated against gold-standard techniques like DXA and isokinetic dynamometry? What are the age-, sex-, and fitness-specific benchmarks for EI to differentiate between normal and pathological muscle quality?