title: Muscle architecture adaptations to knee extensor eccentric training: rectus femoris vs. vastus lateralis.
abstract: BACKGROUND
  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.
authors.affiliation: Exercise Research Laboratory, School of Physical Education, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Bruno Manfredini
authors.initials: BM
authors.lastname: Baroni
authors.forename: Jeam Marcel
authors.initials: JM
authors.lastname: Geremia
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Rodrigues
authors.forename: Rodrigo
authors.initials: R
authors.lastname: De Azevedo Franke
authors.forename: Kiros
authors.initials: K
authors.lastname: Karamanidis
authors.forename: Marco Aurélio
authors.initials: MA
authors.lastname: Vaz
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D006801:Humans; D007717:Knee / Q000502:physiology; D008137:Longitudinal Studies; D008297:Male; D052580:Muscle Stretching Exercises / Q000379:methods*; D052097:Quadriceps Muscle / Q000166:cytology / Q000000981:diagnostic imaging / Q000502:physiology*; D016896:Treatment Outcome; D014463:Ultrasonography; D055815:Young Adult
keywords: eccentric exercise; fascicular geometry; muscle plasticity; quadriceps femoris; ultrasonography