title: Impact of exercise on bone health and contraindication of oral contraceptive use in young women.
abstract: OBJECTIVE
  The effect of quantified resistance and high impact exercise training on bone mass as modified by age and oral contraceptive (OCont) use in young women was studied.
  
  
  METHODS
  Women were categorized by age (18-23 vs 24-31 yr) and OCont use, and were then randomized into either three sessions of resistance exercise plus 60 min.wk-1 of jumping rope or a control group for 24 months. Total body, spine, femoral neck, greater trochanter, Ward's area, and radial bone mineral density (BMD) and/or content (BMC), biochemical markers of bone turnover, dietary intake of calcium, lean body mass, maximal oxygen uptake, and strength were determined at baseline and every 6 months.
  
  
  RESULTS
  Total body (TB) BMC percent change from baseline was higher in exercisers compared with nonexercisers at 6 and 24 months. OCont users had lower bone turnover at baseline and a decrease in TBBMC from baseline compared with non-OCont users at 24 months. Spine BMC and BMD decreased in the exercise and OCont group at 6 months and remained significantly below nonexercisers who used oral contraceptives at 2 yr. Femoral neck BMD also decreased in the exercise and oral contraceptive group at 6 months.
  
  
  CONCLUSIONS
  Exercise prevented a decline in TBBMC seen in the nonexercisers. On the other hand, exercise in oral contraceptive users prevented the increase observed in the spine of the nonexercise plus OCont group.
authors.affiliation: Department of Foods and Nutrition, Purdue University, 1264 Stone Hall, West Lafayette, IN 47907-1264, USA. weavercm@cfs.purdue.edu
authors.forename: C M
authors.initials: CM
authors.lastname: Weaver
authors.forename: D
authors.initials: D
authors.lastname: Teegarden
authors.forename: R M
authors.initials: RM
authors.lastname: Lyle
authors.forename: G P
authors.initials: GP
authors.lastname: McCabe
authors.forename: L D
authors.initials: LD
authors.lastname: McCabe
authors.forename: W
authors.initials: W
authors.lastname: Proulx
authors.forename: M
authors.initials: M
authors.lastname: Kern
authors.forename: D
authors.initials: D
authors.lastname: Sedlock
authors.forename: D D
authors.initials: DD
authors.lastname: Anderson
authors.forename: B M
authors.initials: BM
authors.lastname: Hillberry
authors.forename: M
authors.initials: M
authors.lastname: Peacock
authors.forename: C C
authors.initials: CC
authors.lastname: Johnston
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000032:analysis; D015519:Bone Density; D003276:Contraceptives, Oral / Q000009:adverse effects*; D015444:Exercise; D005260:Female; D006304:Health Status; D006801:Humans; D014891:Weight Lifting
chemical_list: D015415:Biomarkers; D003276:Contraceptives, Oral