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Title: Optimum frequency of exercise for bone health: randomised controlled trial of a high-impact unilateral intervention
Authors: Bailey, Christine A.
Brooke-Wavell, Katherine S.F.
Keywords: Bone mineral density
Femoral neck
Osteoporosis prevention
Premenopausal women
Issue Date: 2010
Publisher: © Elsevier
Citation: BAILEY, C.A. and BROOKE-WAVELL, K., 2010. Optimum frequency of exercise for bone health: randomised controlled trial of a high-impact unilateral intervention. Bone, 46(4), pp.1043-1049.
Abstract: 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.
Description: NOTICE: this is the author’s version of a work that was accepted for publication in Bone. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published at: http://dx.doi.org/10.1016/j.bone.2009.12.001
Version: Accepted for publication
DOI: 10.1016/j.bone.2009.12.001
URI: https://dspace.lboro.ac.uk/2134/15541
Publisher Link: http://dx.doi.org/10.1016/j.bone.2009.12.001
ISSN: 8756-3282
Appears in Collections:Published Articles (Sport, Exercise and Health Sciences)

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