title: Prospective cohort study of the risk factors for stress fractures in Chinese male infantry recruits.
abstract: OBJECTIVE
  To determine potential risk factors that could predict stress fractures over an 8-week basic military training in Chinese male infantry recruits.
  
  
  METHODS
  Recruits from three infantry units enrolled in this prospective study. At baseline, demographic data, personal history of stress fractures, mean duration of weekly exercise and smoking history were recorded on questionnaires and blood samples taken for analysis of bone turnover biomarkers and genetic factors.
  
  
  RESULTS
  Of the 1516 male recruits who volunteered to participate in the study, 1398 recruits provided data for analysis. In total, 189 stress fracture cases were observed (incidence rate: 13.5%) during the 8-week training period. Recruits with stress fractures had a significantly higher incidence of prior fracture history and lower exercise level prior to enrolment compared with those without stress fractures. A significant difference in both allelic frequency and genotypic distribution of the growth differentiation factor 5 (GDF5) gene rs143383 polymorphism was observed between recruits with and without stress fractures. However, no difference in serum bone turnover biomarkers was detected between groups.
  
  
  CONCLUSIONS
  This prospective, cohort study indicates that fracture history, lower exercise level and GDF5 rs143383 may be predictive risk factors for stress fractures in Chinese male infantry recruits.
authors.affiliation: Institute of Orthopaedics, Xijing Hospital, Fourth Military Medical University, Xi'an, Shannxi, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Institute of Training Related Medical Sciences, the 150th Hospital of Chinese PLA, Luoyang, Henan, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Chang
authors.affiliation: Institute of Training Related Medical Sciences, the 150th Hospital of Chinese PLA, Luoyang, Henan, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Huang
authors.affiliation: Institute of Orthopaedics, Xijing Hospital, Fourth Military Medical University, Xi'an, Shannxi, China huangchanglin1945@126.com.
authors.forename: Changlin
authors.initials: C
authors.lastname: Huang
mesh_terms: D000293:Adolescent; D044466:Asian People / Q000706:statistics & numerical data*; D015415:Biomarkers / Q000097:blood; D016723:Bone Remodeling; D002681:China / Q000453:epidemiology; D003710:Demography; D015775:Fractures, Stress / Q000097:blood / Q000453:epidemiology* / Q000235:genetics; D005787:Gene Frequency / Q000235:genetics; D055428:Growth Differentiation Factor 5 / Q000235:genetics; D006801:Humans; D008297:Male; D008889:Military Personnel / Q000706:statistics & numerical data*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D015415:Biomarkers; C525893:GDF5 protein, human; D055428:Growth Differentiation Factor 5
keywords: Bone remodelling; bone turnover biomarkers; growth differentiation factor 5; military recruits; single nucleotide polymorphism; stress fractures