Relationship between anthropometric and electromyographic variables of the scapular muscles

Purpose. To determine the relationship between skinfolds and onset latency of scapular muscles in healthy young adults. Methods. A cross-sectional study was carried out at the Biomechanics and Motor Control Laboratory of Saint Thomas University, Talca, Chile. Overall, 36 participants between 18 and 24 years of age were selected. The axillary, pectoral, and subscapular skinfolds were measured, as well as the electromyographic onset latency of the scapular muscles (serratus anterior and trapezius) when performing a voluntary arm abduction task. The Pearson correlation coefficient was used. Results. There was a positive correlation between the axillary skinfold and the lower trapezius (r = 0.51, p = 0.002) and serratus anterior (r = 0.53, p = 0.001) muscle onset latencies, and also between the subscapular skinfold and the lower trapezius (r = 0.38, p = 0.022) and serratus anterior (r = 0.73, p < 0.001) muscle onset latencies. Conclusions. During a voluntary abduction arm movement, a greater thickness of axillary and subscapular skinfolds is related to an increase in the lower trapezius and serratus anterior muscle onset latencies.