title: Randomised controlled trial of effect of high-impact exercise on selected risk factors for osteoporotic fractures.
abstract: BACKGROUND
  Osteoporotic fractures among the elderly are common, and without preventive measures the burden of these fractures on health-care systems will increase further. The purpose of this randomised controlled study was to evaluate, in premenopausal women, the effects of high-impact loading on several determinants osteoporotic fractures.
  
  
  METHODS
  98 healthy, sedentary female volunteers aged 35-45 years were randomly assigned to either a training (n = 49) or a control group (n = 49). Progressive high-impact exercises were done three times per week for 18 months. We measured bone mineral density (BMD) in specific axial and lower-limb sites, by dual-energy X-ray absorptiometry, at baseline and after 12 and 18 months. Maximum isometric strength, muscular and cardiovascular performance, and dynamic balance were also assessed.
  
  
  RESULTS
  BMD at the femoral neck, a weightbearing site, increased significantly more in the training group (mean 1.6% [95% CI 0.8-2.4]) than in the control group (0.6% [-0.2 to 1.4], p = 0.006). By contrast, at non-weightbearing sites, such as the distal radius, there was no significant difference between the training and control groups (-1.5% [-2.7 to -0.3] vs -0.7% [-1.9 to -0.5], p = 0.60). In the training group there was a significant improvement in vertical jump and predicted oxygen consumption per min at maximum exercise compared with controls.
  
  
  CONCLUSIONS
  High-impact exercises that load bones with a rapidly rising force profile in versatile movements improve skeletal integrity, muscular performance, and dynamic balance in premenopausal women. If done on a regular basis, this type of exercise may help decrease the risk of osteoporotic fractures in later life. Long-term studies are required to show whether these 18-month results can be translated into long-term benefit.
authors.affiliation: UKK Institute for Health Promotion Research, Tampere, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Heinonen
authors.forename: P
authors.initials: P
authors.lastname: Kannus
authors.forename: H
authors.initials: H
authors.lastname: Sievänen
authors.forename: P
authors.initials: P
authors.lastname: Oja
authors.forename: M
authors.initials: M
authors.lastname: Pasanen
authors.forename: M
authors.initials: M
authors.lastname: Rinne
authors.forename: K
authors.initials: K
authors.lastname: Uusi-Rasi
authors.forename: I
authors.initials: I
authors.lastname: Vuori
mesh_terms: D000328:Adult; D015519:Bone Density; D001842:Bone and Bones / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena; D015444:Exercise; D005260:Female; D050723:Fractures, Bone / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D007537:Isometric Contraction; D008875:Middle Aged; D009132:Muscles / Q000378:metabolism / Q000502:physiology; D010024:Osteoporosis / Q000150:complications / Q000517:prevention & control*; D011446:Prospective Studies; D012307:Risk Factors