title: A meta-analysis of brief high-impact exercises for enhancing bone health in premenopausal women.
abstract: A snapshot of current evidence from 6 randomised controlled trials for the effects of short bouts of high-impact exercises in 256 women via meta-analysis reveals that ample osteogenic response could be realised at the femoral neck and trochanter of premenopausal women with rest-inserted bouts of few mechanical bone loading cycles.
  
  
  BACKGROUND
  Exercise is an important means of improving bone health and preventing osteoporosis. Brief bouts of simple exercises may be useful for aiding lifestyle compliance to physical activity. This study aimed to review the evidence on the effect of brief, high-impact exercise on bone health among premenopausal women.
  
  
  METHODS
  A structured and comprehensive search of databases was undertaken along with hand searching of key journals and reference lists to locate relevant studies published and unpublished up to January 2011. Six randomised controlled trials met predetermined inclusion criteria. Brief high-impact exercises (<30 min) were examined for their effect on bone mineral density (BMD) among premenopausal women. Trial quality was assessed using the Effective Public Health Practice Project quality assessment tool. Study outcomes for analysis, absolute change (grams per square centimetre) or relative change (in percent) in BMD at femoral neck, trochanter and lumbar spine were compared by calculating standardised mean difference (SMD) using fixed- and random effects models.
  
  
  RESULTS
  Quality of included trials varied from medium to high on a scale of 1 to 3. Brief bouts of exercise led to significant increases in femoral neck BMD (SMD = 0.64, 95% confidence interval (CI) = 0.38, 0.90, overall effect Z value = 4.84, p = 0.001); a modest increase in trochanteric BMD (SMD = 0.36, 95% CI = 0.10, 0.61, Z value = 2.08, p = 0.04) and no increase in spinal BMD (SMD = 0.04, 95% CI= -0.23, 0.31, Z value = 0.26, p = 0.79).
  
  
  CONCLUSIONS
  Based on the meta-analysis, brief high-impact exercise improves BMD at the hip but not at the lumbar spine. Effectiveness of this form of exercise as a lifestyle physical activity for prevention of osteoporosis should be explored in larger populations.
authors.affiliation: Centre for Sport, Health and Exercise Research, Staffordshire University, Leek Road, Stoke on Trent ST4 2DF, UK. o.babatunde@staffs.ac.uk
authors.forename: O O
authors.initials: OO
authors.lastname: Babatunde
authors.forename: J J
authors.initials: JJ
authors.lastname: Forsyth
authors.forename: C J
authors.initials: CJ
authors.lastname: Gidlow
mesh_terms: D015519:Bone Density / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D005269:Femur / Q000502:physiology; D005272:Femur Neck / Q000502:physiology; D006801:Humans; D008019:Life Style; D017697:Premenopause / Q000502:physiology*; D016032:Randomized Controlled Trials as Topic