title: Effect of eccentric contractions of elbow flexor on bone formation and resorption markers.
abstract: OBJECTIVE
  This study aimed to investigate the effects of eccentric contractions (ECs) of the biceps brachii muscle on bone metabolism markers.
  
  
  METHODS
  Eight untrained subjects (20.0±0.5 years) performed 5 sets of 6 maximal ECs of the elbow flexors with a 2-min rest interval between each set. Blood samples were collected at 6 time points: before (Pre) ECs, immediately after (Post) ECs, and two hours (2 hours), 1 (day 1), 3 (days 3), and 5 days (days 5) after ECs. We measured the levels of the bone formation marker osteocalcin (OC) and the resorption marker tartrate-resistant acid phosphatase 5b (TRACP-5b). In addition, we measured the isometric tetanic torque and the levels of myoglobin (Mb), creatine kinase (CK), blood lactate, and insulin-like growth factor-1 (IGF-1).
  
  
  RESULTS
  The results showed 1) CK and Mb levels increased significantly by days 3 and 5 (P<0.05); 2) OC levels significantly decreased in Post and 2 hours (P<0.01) and TRACP-5b levels significantly increased in Post (P<0.01); 3) OC positively correlated with the total work output in Post, 2 hours, and days 5 (Post: r=0.79, P<0.05; 2 hours: r=0.82, P<0.01; days 5: r=0.79, P<0.05); and 4) TRACP-5b levels positively correlated with IGF-1 levels (r=0.69, P<0.01).
  
  
  CONCLUSIONS
  We conclude that a single bout of ECs of the biceps has a negative effect on bone metabolism in the acute phase.
authors.affiliation: Graduate School of Medicine, Juntendo University, Tokyo, Japan - ochi @gen.meijigakuin.ac.jp.
authors.forename: Y
authors.initials: Y
authors.lastname: Tsuchiya
authors.forename: K
authors.initials: K
authors.lastname: Sakuraba
authors.forename: E
authors.initials: E
authors.lastname: Ochi
mesh_terms: D000135:Acid Phosphatase / Q000097:blood; D000328:Adult; D015415:Biomarkers / Q000097:blood; D001862:Bone Resorption; D004551:Elbow Joint / Q000502:physiology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007527:Isoenzymes / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D015675:Osteocalcin / Q000097:blood; D010012:Osteogenesis / Q000502:physiology*; D000071681:Tartrate-Resistant Acid Phosphatase
chemical_list: D015415:Biomarkers; D007527:Isoenzymes; D015675:Osteocalcin; D019344:Lactic Acid; D007334:Insulin-Like Growth Factor I; C000605510:ACP5 protein, human; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase