Document Detail


Optimum frequency of exercise for bone health: randomised controlled trial of a high-impact unilateral intervention.
MedLine Citation:
PMID:  20004758     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
INTRODUCTION: Exercise can increase bone strength, but to be effective in reducing fracture risk, exercise must be feasible enough to be adopted into daily life and influence potentially vulnerable skeletal sites such as the superolateral cortex of the femoral neck, where thinning is associated with increased fracture risk. Brief, high-impact exercise increases femoral neck bone density but the optimal frequency of such exercise and the location of bone accrual is unknown. This study thus examined (1) the effectiveness of different weekly frequencies of exercise on femoral neck BMD and (2) whether BMD change differed between hip sites using a high-impact, unilateral intervention. METHODS: Healthy premenopausal women were randomly assigned to exercise 0, 2, 4, or 7 days/week for 6 months. The exercise intervention incorporated 50 multidirectional hops on one randomly selected leg. BMD was measured by DXA at baseline and after 6 months of exercise. Changes in the exercise leg were compared between groups using ANCOVA, with change in the control leg and baseline BMD as covariates. RM-MANOVA was conducted to determine whether bone changes from exercise differed between hip sites. RESULTS: 61 women (age 33.6+/-11.1 years) completed the intervention. Compliance amongst exercisers was 86.7+/-10.6%. Peak ground reaction forces during exercise increased from 2.5 to 2.8 times body weight. The change in femoral neck BMD in the exercise limb (adjusted for change in the control limb and baseline BMD) differed between groups (p=0.015), being -0.3% (-1.2 to 0.6), 0.0% (-1.0 to 1.0), 0.9% (-0.1 to 2.0) and 1.8% (0.8 to 2.8) in those exercising 0, 2, 4 and 7 days per week, respectively. When BMD changes at upper neck, lower neck and trochanter were compared using RM-MANOVA, a significant exercise effect was observed (p=0.048), but this did not differ significantly between sites (p=0.439) despite greatest mean increases at the upper femoral neck. CONCLUSIONS: Brief, daily hopping exercises increased femoral neck BMD in premenopausal women but less frequent exercise was not effective. Brief high-impact exercise may have a role in reducing hip fragility, but may need to be performed frequently for optimal response.
Authors:
Christine A Bailey; Katherine Brooke-Wavell
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial     Date:  2010-01-06
Journal Detail:
Title:  Bone     Volume:  46     ISSN:  1873-2763     ISO Abbreviation:  Bone     Publication Date:  2010 Apr 
Date Detail:
Created Date:  2010-03-19     Completed Date:  2010-06-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8504048     Medline TA:  Bone     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1043-9     Citation Subset:  IM    
Copyright Information:
Copyright 2009 Elsevier Inc. All rights reserved.
Affiliation:
School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK.
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MeSH Terms
Descriptor/Qualifier:
Adult
Analysis of Variance
Bone Density / physiology*
Exercise / physiology*
Exercise Therapy
Female
Femur Neck / physiology*
Health Behavior
Humans
Longitudinal Studies
Middle Aged
Physical Fitness
Treatment Outcome

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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