Muscle echo intensity: reliability and conditioning factors.

The echo intensity reliability was function of the ROI size. Muscle and gender variability in echo intensity was likely due to differences in fibrous and adipose tissue content and distribution. Possible explanations for the observed correlations between muscle echo intensity and subcutaneous layer thickness include the dependence of both variables on total body adiposity or the direct dependence of the extent of intramuscular fat on the amount of subcutaneous fat.