title: Changes in bone turnover markers during the close season in elite football (soccer) players.
abstract: OBJECTIVE
  Bone turnover marker changes in response to physical activity are well documented. There is, however, little information on the extent and severity of skeletal de-conditioning in athletes in response to rest periods. This study analyses changes in markers of bone resorption and bone formation during the close season within the squad of an English Football Association Championship club.
  
  
  METHODS
  Evaluation was performed on the first team football squad just before the end of the 2007/2008 football season and again 8 weeks later before pre-season testing and training.
  
  
  METHODS
  Bone resorption was measured by serum concentration of C-terminal telopeptide (CTx) and bone formation by serum concentration of the N-terminal propeptide of type I procollagen (PINP). Twenty football players aged from 18 to 36 years (mean 23.6 years) were included in the study.
  
  
  RESULTS
  The mean change in CTx during the close season was +0.14 ng/ml (95% CI: 0.21 to 0.06, p=0.001). The mean change in PINP was -10.8 ng/ml (95% CI: -3.9 to -17.7, p=0.004).
  
  
  CONCLUSIONS
  In professional football players, a close season rest of 8 weeks results in an increase in bone resorption and a decrease in bone formation markers. This imbalance between formation and resorption may have negative effects on bone mass and structure. Future research should focus on understanding the many factors that could contribute to the changes found in the study during the close season.
authors: Institute of Sport, Exercise and Health, School of Human Health and Performance, University College, London, United Kingdom. rweiler@doctors.org.uk
authors: Richard
authors: R
authors: Weiler
authors: Richard
authors: R
authors: Keen
authors: Roger
authors: R
authors: Wolman
mesh_terms: D000293:Adolescent; D000328:Adult; D056352:Athletes; D015415:Biomarkers / Q000097:blood; D001861:Bone Regeneration / Q000502:physiology*; D024042:Collagen Type I / Q000097:blood; D006801:Humans; D008297:Male; D010446:Peptide Fragments / Q000097:blood; D010455:Peptides / Q000097:blood; D011347:Procollagen / Q000097:blood; D012146:Rest / Q000502:physiology*; D012916:Soccer / Q000502:physiology*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D024042:Collagen Type I; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide