title: The relationship of creatine kinase variability with body composition and muscle damage markers following eccentric muscle contractions.
abstract: OBJECTIVE
  The purpose of the study was to investigate the relationship between CK variability and body composition and muscle damage markers following eccentric exercise.
  
  
  METHODS
  Total 119 healthy male subjects were recruited to perform 50 eccentric contractions consisted of 2 sets of 25 contractions. Then, blood creatine kinase (CK) activity was analyzed to divide into three groups based on their CK activity levels. Maximum isometric strength (MIS), muscle soreness (SOR) and body composition data were obtained before and after exercise.
  
  
  RESULTS
  The results showed that high CK responders had a significant decrease in MIS (p<0.001) and greater SOR (p<0.01) following eccentric exercise compared to low CK responders. Percent body fat was also higher in high responders compared to low responders (p=0.014). Peak CK activity was significantly correlated with MIS and SOR but no correlation with % body fat, muscle mass, and body mass index.
  
  
  CONCLUSIONS
  CK variability following eccentric exercise is closely related to MIS and SOR and % body fat may be a potent factor for CK variability.
authors.affiliation: College of Physical Education, Kookmin University, Seoul, Republic of Korea.
authors.forename: Jooyoung
authors.initials: J
authors.lastname: Kim
authors.affiliation: College of Physical Education, Kookmin University, Seoul, Republic of Korea.
authors.forename: Joohyung
authors.initials: J
authors.lastname: Lee
keywords: CK variability; muscle damage; muscle soreness