title: Association between the stress fracture and bone metabolism/quality markers in lacrosse players.
abstract: BACKGROUND
  Overuse injury including stress fracture is a serious problem for athletes. Recently, the importance of bone metabolism and quality as factors preventing overuse injury has been increasingly recognized. Hence, we hypothesized that markers of bone metabolism and quality are related to overuse injuries.
  
  
  METHODS
  The subjects, which were elite university lacrosse players (male, n = 35; age, 19.8 ± 1.1; female, n = 49; age, 20.0 ± 1.0), were divided into a stress fracture group and a control group. We measured the subjects' physical characteristics (height, weight, body mass index, and body fat) and bone architecture was evaluated using quantitative ultrasound. Bone alkaline phosphatase, N-telopeptide cross-link of type I collagen, tartrate-resistant acid phosphatase 5b (TRAP-5b), homocysteine, and pentosidine were measured from blood samples obtained from all subjects.
  
  
  RESULTS
  No significant difference was observed between groups with respect to height, weight, body mass index, and body fat, as well as quantitative ultrasound. Further, there were no significant differences in the levels of bone alkaline phosphatase, N-telopeptide cross-link of type I collagen, or TRAP-5b between stress fracture and control groups in all subjects and in male subjects. However, a significant increase in TRAP-5b level was observed in the stress fracture group compared with the control in the female subjects (409.9 ± 209.3 and 318.6 ± 81.6 mU/dL, respectively; P < 0.05). Homocysteine and pentosidine did not differ between groups.
  
  
  CONCLUSIONS
  These results suggest that osteoclast activity of female athletes with stress fractures may be enhanced by TRAP-5b.
authors.affiliation: Department of Sports Medicine, Graduate School of Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Wakamatsu
authors.forename: Keishoku
authors.initials: K
authors.lastname: Sakuraba
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Asako
authors.initials: A
authors.lastname: Maruyama
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Tsuchiya
authors.forename: Jiro
authors.initials: J
authors.lastname: Shikakura
authors.forename: Eisuke
authors.initials: E
authors.lastname: Ochi
keywords: TRAP-5b; overuse injury; stress fracture