title: Muscular adaptations and insulin-like growth factor-1 responses to resistance training are stretch-mediated.
abstract: BACKGROUND
  Modulation of muscle characteristics was attempted through altering muscle stretch during resistance training. We hypothesized that stretch would enhance muscle responses.
  
  
  METHODS
  Participants trained for 8 weeks, loading the quadriceps in a shortened (SL, 0-50° knee flexion; n=10) or lengthened (LL, 40-90°; n=11) position, followed by 4 weeks of detraining. Controls (CON; n=10) were untrained. Quadriceps strength, vastus lateralis architecture, anatomical cross-sectional area (aCSA), and serum insulin-like growth factor-1 (IGF-1) were measured at weeks 0, 8, 10, and 12.
  
  
  RESULTS
  Increases in fascicle length (29±4% vs. 14±4%), distal aCSA (53±12% vs. 18±8%), strength (26±6% vs. 7±3%), and IGF-1 (31±6% vs. 7±6%) were greater in LL compared with SL muscles (P<0.05). No changes occurred in CON. Detraining decrements in strength and aCSA were greater in SL than LL muscles (P<0.05).
  
  
  CONCLUSIONS
  Enhanced muscle in vivo (and somewhat IGF-1) adaptations to resistance training are concurrent with muscle stretch, which warrants its inclusion within training.
authors.forename: Gerard
authors.initials: G
authors.lastname: McMahon
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Morse
authors.forename: Adrian
authors.initials: A
authors.lastname: Burden
authors.forename: Keith
authors.initials: K
authors.lastname: Winwood
authors.forename: Gladys Leopoldine
authors.initials: GL
authors.lastname: Onambélé
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D004576:Electromyography; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009470:Muscle Spindles / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D010865:Pilot Projects; D055070:Resistance Training; D013710:Tendons / Q000502:physiology; D055815:Young Adult
chemical_list: D007334:Insulin-Like Growth Factor I