title: Stress fractures in female army recruits: implications of bone density, calcium intake, and exercise.
abstract: OBJECTIVE
  To identify characteristics and factors associated with increased risk for stress fractures in military women.
  
  
  METHODS
  Case-control study to retrospectively examine physical activity, prior calcium intake, and bone density as predictors of stress fractures.
  
  
  METHODS
  A military training installation which incorporates physical training for women.
  
  
  METHODS
  Forty-nine female soldiers with confirmed stress fractures (cases) and 78 female soldiers with no orthopedic injuries (controls), aged 18 to 33 years.
  
  
  METHODS
  Retrospective self-reports of habitual exercise, sports participation, and food intake; current height, weight, and body mass index (BMI); demographic variables (age, ethnicity, menstrual patterns, smoking habits); and bone density on radiologically defined stress fractures.
  
  
  RESULTS
  Cases and controls were similar in height, weight, and BMI. Measurements of bone density (g/cm2) at the trochanter (cases, 0.77+/-0.09; controls, 0.77+/-0.08); femoral neck (cases, 0.94+/-0.10; controls, 0.94+/-0.09); Ward's triangle (cases, 0.91+/-0.11; controls, 0.93+/-0.11); lumbar spine (cases, 1.21+/-0.12; controls, 1.24+/-0.10); and radius shaft (cases, 0.67+/-0.09; controls, 0.68+/-0.05) were not different between groups. Calcium intake was not different between groups (cases, 1154+/-751 mg/day; controls, 944+/-513 mg/day) and did not correlate with bone density (r=0.01 to -0.06 at four sites). Sports participation positively correlated with bone density in the hip (r=0.49). Leisure activity energy expenditure (kcal/day) tended toward association with lower stress fracture risk as expenditure level increased (p=0.06).
  
  
  CONCLUSIONS
  Stress fracture in female Army recruits was not correlated with bone density or calcium intake during adolescence, although a weak relationship to prior physical activity was observed.
authors.affiliation: Department of Food Science and Human Nutrition, Colorado State University, Ft. Collins, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: Cline
authors.forename: G R
authors.initials: GR
authors.lastname: Jansen
authors.forename: C L
authors.initials: CL
authors.lastname: Melby
mesh_terms: D000293:Adolescent; D000328:Adult; D000568:Amenorrhea; D015992:Body Mass Index; D015519:Bone Density; D002136:Calcium, Dietary / Q000008:administration & dosage*; D016022:Case-Control Studies; D004734:Energy Metabolism; D015444:Exercise; D005260:Female; D015775:Fractures, Stress / Q000453:epidemiology* / Q000209:etiology; D006615:Hip; D006801:Humans; D008889:Military Personnel; D009747:Nutritional Physiological Phenomena; D012189:Retrospective Studies; D012307:Risk Factors; D013177:Sports; D011795:Surveys and Questionnaires
chemical_list: D002136:Calcium, Dietary