TRICEPS SURAE MUSCLE-TENDON ARCHITECTURE DIFFERENCES IN AFRICAN AMERICAN AND CAUCAUSIAN WOMEN

Abstract

In common human movements, such as walking, running, and jumping, the triceps surae muscle is a main agonist to propel the body, and the compliant and long Achilles tendon has a large capacity to store and reuse elastic energy. PURPOSE The purpose of this study was to compare triceps surae muscle architecture (maximal cross-sectional area, length, and shape) and gastrocnemius tendon length in 14 African American and 19 Caucasian normal-weight premenopausal women. METHODS Magnetic resonance imaging was used to determine muscle cross-sectional areas along the length of the leg for total triceps surae and its three individual muscles. Lengths of gastrocnemius tendons were estimated by subtracting muscle length from lower leg length as measured by dual-energy X-ray absorptiometry. RESULTS Both medial and lateral gastrocnemius muscle lengths were significantly shorter (P ≤ 0.02) and tendons for these muscles were significantly longer (P ≤ 0.04) in Black women. Medial gastrocnemius (P=0.04) and total triceps surae (P=0.008) muscle shapes were significantly different across ethnicity despite no significant ethnic differences (P ≥ 0.31) in maximal cross-sectional area for any triceps surae muscles. CONCLUSION Findings indicate architectural differences between African American and Caucasian women in gastrocnemius muscle length and shape and gastrocnemius tendon length. Considering the important influences of differences in muscle and tendon architecture on mechanical force and power, these findings suggest a mechanism that may at least partially explain reported ethnic differences in certain types of performance. Supported by NIH Grants RO1 DK49779 and RO1 DK51684.