Muscle architecture adaptations to knee extensor eccentric training: Rectus femoris vs. vastus lateralis


  • This study was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES Brazil), Financiadora de Estudos e Projetos (FINEP Brazil), and Conselho Nacional de Pesquisa (CNPq Brazil).


Introduction: Changes in muscle architecture induced by eccentric knee extensor training remain unclear, as well the adaptive responses of synergistic knee extensor muscles with different geometrical designs. Methods: Ultrasonography images were taken from rectus femoris (RF) and vastus lateralis (VL) of 20 male volunteers before and after a non-training control period of 4 weeks, and additional evaluations were performed after 4, 8, and 12 weeks of isokinetic eccentric training. Results: RF and VL had significant changes in muscle architecture within the first 4 training weeks, and the adaptive response throughout the intervention was similar. Muscle thickness increased by around 7–10%, fascicle length increased 17–19%, and pennation angle was unchanged. Conclusions: Increased muscle thickness due to eccentric training was related to increased fascicle length and not to pennation angle changes. Although RF and VL have a different fascicular geometry, they had similar morphological adaptations to eccentric training. Muscle Nerve 48: 498–506, 2013