title: Effects of high-impact exercise on bone mineral density: a randomized controlled trial in premenopausal women.
abstract: BACKGROUND
  The purpose of this randomized controlled study was to assess the effects of high-impact exercise on the bone mineral density (BMD) of premenopausal women at the population level.
  
  
  METHODS
  The study population consisted of a random population-based sample of 120 women from a cohort of 5,161 women, aged 35 to 40 years. They were randomly assigned to either an exercise or control group. The exercise regimen consisted of supervised, progressive high-impact exercises three times per week and an additional home program for 12 months. BMD was measured on the lumbar spine (L1-L4), proximal femur, and distal forearm, by dual-energy X-ray absorptiometry at baseline and after 12 months. Calcaneal bone was measured using quantitative ultrasound.
  
  
  RESULTS
  Thirty-nine women (65%) in the exercise group and 41 women (68%) in the control group completed the study. The exercise group demonstrated significant change compared with the control group in femoral neck BMD (1.1% vs -0.4%; p=0.003), intertrochanteric BMD (0.8% vs -0.2%; p=0.029), and total femoral BMD (0.1% vs -0.3%; p=0.006). No exercise-induced effects were found in the total lumbar BMD or in the lumbar vertebrae L2-L4. Instead, L1 BMD (2.2% vs -0.4%; p=0.002) increased significantly more in the exercise group than in the control group. Calcaneal broadband ultrasound attenuation showed also a significant change in the exercise group compared with the control group (7.3% vs -0.6%; p=0.015). The changes were also significant within the exercise group, but not within the control group. There were no significant differences between or within the groups in the distal forearm.
  
  
  CONCLUSIONS
  This study indicates that high-impact exercise is effective in improving bone mineral density in the lumbar spine and upper femur in premenopausal women, and the results of the study may be generalized at the population level. This type of training may be an efficient, safe, and inexpensive way to prevent osteoporosis later in life.
authors.affiliation: Department of Medical Technology, University of Oulu, PO Box 5000, 90014, Oulu, Finland. avainion@paju.oulu.fi <avainion@paju.oulu.fi>
authors.forename: Aki
authors.initials: A
authors.lastname: Vainionpää
authors.forename: Raija
authors.initials: R
authors.lastname: Korpelainen
authors.forename: Juhani
authors.initials: J
authors.lastname: Leppäluoto
authors.forename: Timo
authors.initials: T
authors.lastname: Jämsä
mesh_terms: D000328:Adult; D015519:Bone Density / Q000502:physiology*; D002111:Calcaneus / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D005269:Femur / Q000502:physiology; D005542:Forearm; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology; D010024:Osteoporosis / Q000517:prevention & control; D017697:Premenopause / Q000502:physiology*; D013314:Stress, Mechanical