title: Muscle damage and repeated bout effect induced by enhanced eccentric squats.
abstract: BACKGROUND
  Muscle damage and repeated bout effect have been studied after pure eccentric-only exercise. The aim of this study was to evaluate muscle damage and repeated bout effect induced by enhanced eccentric squat exercise using flywheel device.
  
  
  METHODS
  Thirteen healthy males volunteered for this study. Creatine kinase blood activity (CK), quadriceps isometric peak torque and muscle soreness were used as markers of muscle damage. The dependent parameters were measured at baseline, immediately after and each day up to 96 hours after the exercise session. The intervention consisted of 100 repetitions of enhanced eccentric squat exercise using flywheel device. The same protocol was repeated after 4 weeks.
  
  
  RESULTS
  After the first bout, CK and muscle soreness were significantly greater (P<0.05) than baseline respectively up to 72 and 96 hours. Isometric peak torque was significantly lower (P<0.05) up to 72 hours. After the second bout, CK showed no significant increase (P>0.05), while isometric peak torque and muscle soreness returned to values similar to baseline after respectively 48 and 72 hours. All muscle damage markers were significantly lower after second compared to first bout.
  
  
  CONCLUSIONS
  The enhanced eccentric exercise induced symptoms of muscle damage up to 96 hours. However, it provided muscle protection after the second bout, performed four weeks later. Although it was not eccentric-only exercise, the enhancement of eccentric phase provided muscle protection.
authors.affiliation: Department of Neurological and Movement Sciences, University of Verona, Verona, Italy - giuseppe.coratella@univr.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Coratella
authors.affiliation: Department of Neurological and Movement Sciences, University of Verona, Verona, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Chemello
authors.affiliation: Department of Neurological and Movement Sciences, University of Verona, Verona, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Schena
mesh_terms: D000328:Adult; D003402:Creatine Kinase / Q000097:blood; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000293:injuries* / Q000473:pathology / Q000502:physiology*; D063806:Myalgia / Q000473:pathology*; D013997:Time Factors; D019415:Torque
chemical_list: D003402:Creatine Kinase