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Muscle arquitecture in four groups of young women

Abstract:

Muscle architecture describes the geometric design of a muscle. It will have a great influence in the force generating capacity and the shortening velocity of skeletal muscle. The purposes of this study were to analyse and compare, in four groups of young women with different levels of physical activity, the architectural characteristics of lower limb extensor muscles, and the differences between muscles. Twelve elite female volleyball players (ELITE), 12 club level female Volleyball players (MEDIO), 10 physical education students (EST) and 12 sedentary young women (SED) volunteered for the study. Muscle thickness, pennation angles and fascicle length of vastus lateralis (VL), gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) were analysed by means of ultrasonography, and the anthropometric characteristics of each group were determined. The differences among muscles were similar to those reported in the literature, and were related to the functional use of each muscle. The VL muscle architecture was related to the development of great forces at high contraction velocities, because of its muscle thickness and fascicle length. There were significant differences in muscle thicknesses and fascicle lengths between SED and the groups of volleyball players (MED and ELITE). These differences would be related to the ability to develop higher levels of force and velocity, due to the greater number of in-parallel and in-series sarcomeres. The longer fascicle lengths found in the ELITE group would have been caused by their specific training, mainly composed by jumps and explosive movements that led to forced stretching of muscle fascicles. The correlations between fascicle lengths and muscle thickness in ELITE and MED are similar to those found in sports where explosive strength and speed are essential for the performance.