title: Functional and morphological changes in the quadriceps muscle induced by eccentric training after ACL reconstruction.
abstract: OBJECTIVE
  The purpose of this study was to investigate the contributions of functional and morphological factors in the recovery of the quadriceps muscle after anterior cruciate ligament (ACL) reconstruction.
  
  
  METHODS
  Nine subjects (31.3±5.8 years) underwent eccentric exercise sessions twice a week for 12 weeks. Quadriceps muscle function was evaluated using an isokinetic dynamometer (isometric and eccentric peak torque) and electromyography (RMS). Morphological changes were measured using magnetic resonance imaging.
  
  
  RESULTS
  The initial evaluation showed a significant deficit in knee extensor torque in the involved limb and significant muscle atrophy along the length of the quadriceps. EMG activity was lower in all tested situations. Eccentric training significantly increased isokinetic torque (from 199±51 to 240±63, p<0.05, respectively) and quadriceps area, with the greatest hypertrophy in the proximal thigh region (from 169±27 to 189±25.8 cm², p<0.01). The EMG activity of vastus medialis increased after the first six weeks of eccentric training. The increased extensor torque was correlated with quadriceps cross-sectional area (r=0.81, p<0.01) and EMG activity (r=0.69, p<0.05). After twelve weeks of training, there was a correlation only between torque and cross-sectional area (r=0.78, p<0.01).
  
  
  CONCLUSIONS
  1) eccentric training proved to be a potent resource for the quadriceps recovery, both morphologically and functionally, 2) the contributions of functional and morphological factors varied according to the length of training.
authors.affiliation: Physical Therapy Department, Universidade Federal do Rio Grande do Norte, Natal, RN, Brazil. brasileiro@ufrnet.br
authors.forename: Jamilson S
authors.initials: JS
authors.lastname: Brasileiro
authors.forename: Olga M S F
authors.initials: OM
authors.lastname: Pinto
authors.forename: Mariana A
authors.initials: MA
authors.lastname: Avila
authors.forename: Tania F
authors.initials: TF
authors.lastname: Salvini
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D005081:Exercise Therapy / Q000379:methods; D006801:Humans; D008297:Male; D052097:Quadriceps Muscle / Q000033:anatomy & histology* / Q000502:physiology*; D020127:Recovery of Function