title: Factors affecting bone loss in female endurance athletes: a two-year follow-up study.
abstract: BACKGROUND
  Low bone mass leading to stress fractures is a well-known and yet unsolved problem among female athletes.
  
  
  OBJECTIVE
  To quantify the rate of bone loss in healthy female athletes and investigate the effects of estrogen and vitamin K supplementation on bone loss.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  We classified 115 female endurance athletes into amenorrheic, eumenorrheic, or estrogen-supplemented groups and randomized them to receive either placebo or vitamin K(1). The bone mineral densities of the subjects' femoral neck and lumbar spine were measured at baseline and after 2 years.
  
  
  RESULTS
  Bone mineral density in the lumbar spine remained constant, but bone density in the femoral neck had decreased significantly after 2 years in all three subgroups. The decrease was higher in amenorrheic (-6.5% +/- 4.0%) than in eumenorrheic (-3.2% +/- 4.1%) and estrogen-supplemented athletes (-3.9% +/- 3.1%). Supplementation with vitamin K did not affect the rate of bone loss.
  
  
  CONCLUSIONS
  The rate of bone loss in all three subgroups of female athletes was unexpectedly high; neither estrogen nor vitamin K supplementation prevented bone loss.
  
  
  CONCLUSIONS
  High-intensity training maintained over several years must be regarded in women as a risk factor for osteoporosis, and protocols for optimal treatment should be developed.
authors: Department of Biochemistry, University of Maastricht, Maastricht, The Netherlands.
authors: Lavienja A J L M
authors: LA
authors: Braam
authors: Marjo H J
authors: MH
authors: Knapen
authors: Piet
authors: P
authors: Geusens
authors: Fred
authors: F
authors: Brouns
authors: Cees
authors: C
authors: Vermeer
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D015519:Bone Density; D004967:Estrogens / Q000008:administration & dosage; D005260:Female; D005269:Femur; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D008159:Lumbar Vertebrae; D008875:Middle Aged; D010024:Osteoporosis / Q000209:etiology* / Q000517:prevention & control; D010807:Physical Endurance / Q000502:physiology*; D011446:Prospective Studies; D012307:Risk Factors; D014812:Vitamin K / Q000008:administration & dosage
chemical_list: D004967:Estrogens; D014812:Vitamin K