title: Muscle Damage following Maximal Eccentric Knee Extensions in Males and Females.
abstract: OBJECTIVE
  To investigate whether there is a sex difference in exercise induced muscle damage.
  
  
  METHODS
  Vastus Lateralis and patella tendon properties were measured in males and females using ultrasonography. During maximal voluntary eccentric knee extensions (12 reps x 6 sets), Vastus Lateralis fascicle lengthening and maximal voluntary eccentric knee extensions torque were recorded every 10° of knee joint angle (20-90°). Isometric torque, Creatine Kinase and muscle soreness were measured pre, post, 48, 96 and 168 hours post damage as markers of exercise induced muscle damage.
  
  
  RESULTS
  Patella tendon stiffness and Vastus Lateralis fascicle lengthening were significantly higher in males compared to females (p<0.05). There was no sex difference in isometric torque loss and muscle soreness post exercise induced muscle damage (p>0.05). Creatine Kinase levels post exercise induced muscle damage were higher in males compared to females (p<0.05), and remained higher when maximal voluntary eccentric knee extension torque, relative to estimated quadriceps anatomical cross sectional area, was taken as a covariate (p<0.05).
  
  
  CONCLUSIONS
  Based on isometric torque loss, there is no sex difference in exercise induced muscle damage. The higher Creatine Kinase in males could not be explained by differences in maximal voluntary eccentric knee extension torque, Vastus Lateralis fascicle lengthening and patella tendon stiffness. Further research is required to understand the significant sex differences in Creatine Kinase levels following exercise induced muscle damage.
authors.affiliation: Department of Sport, Exercise and Rehabilitation, Northumbria University, Newcastle-Upon-Tyne, United Kingdom.|Institute for Performance Research, Department of Exercise and Sport Science, Manchester Metropolitan University Cheshire, Manchester, United Kingdom.
authors.forename: K M
authors.initials: KM
authors.lastname: Hicks
authors.affiliation: Institute for Performance Research, Department of Exercise and Sport Science, Manchester Metropolitan University Cheshire, Manchester, United Kingdom.
authors.forename: G L
authors.initials: GL
authors.lastname: Onambélé
authors.affiliation: Institute for Performance Research, Department of Exercise and Sport Science, Manchester Metropolitan University Cheshire, Manchester, United Kingdom.
authors.forename: K
authors.initials: K
authors.lastname: Winwood
authors.affiliation: Institute for Performance Research, Department of Exercise and Sport Science, Manchester Metropolitan University Cheshire, Manchester, United Kingdom.
authors.forename: C I
authors.initials: CI
authors.lastname: Morse
mesh_terms: D000328:Adult; D003402:Creatine Kinase / Q000097:blood; D055119:Elastic Modulus; D015444:Exercise; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D009119:Muscle Contraction; D063806:Myalgia / Q000097:blood / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D017847:Patellar Ligament / Q000000981:diagnostic imaging / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012737:Sex Factors; D019415:Torque; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D003402:Creatine Kinase