Upper extremity assessment of muscularity in young children

An investigation involving 16 boys and 16 girls, 7 to 9 years of age, was conducted for the following purposes: to assess the reliability of an ultrasonic procedure for measuring skeletal muscle thickness at two sites on the upper arm; and to determine the association between these ultrasonic measurements and corresponding circumference and net circumference measures in children. B-mode ultrasound was used to determine muscle thickness at both arm sites. A controlled-tension Gulick tape was used for circumference measures, and skinfold calipers were used to obtain the correction factor for the net circumference measurement. Reliability coefficients (intraclass correlations) were high for sonograms at both the anterior and posterior sites. Associations (Pearson correlations) between muscle sonograms and arm circumference measures were moderately high in boys and low to moderate in girls. It was concluded that anterior and posterior upper arm muscle sonograms can be reliably obtained in young children for scans repeated within 30 minutes. It was also concluded that arm circumference measures are more highly associated with corresponding muscle sonograms in boys than in girls. J Orthop Sports Phys Ther 1987;8(8):397-401.