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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|
|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|
|Publisher Link: ||http://dx.doi.org/10.1016/j.bone.2009.12.001|
|Appears in Collections:||Published Articles (Sport, Exercise and Health Sciences)|
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