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Physical Activity for Bone Health: How Much and/or How Hard?

journal contribution
posted on 01.05.2020, 08:52 by Alexander Rowlands, Charlotte Edwardson, Nathan Dawkins, Ben Maylor, Kristen Metcalf, Kathleen Janz

Purpose:

High-impact physical activity is associated with bone health, but higher volumes of lower intensity activity may also be important. The aims of this study were to: 1) investigate the relative importance of volume and intensity of physical activity accumulated during late adolescence for bone health at age 23; and 2) illustrate interpretation of the results.

Methods:

This is a secondary analysis of data from the Iowa Bone Development Study, a longitudinal study of bone health from childhood through to young adulthood. The volume (average acceleration) and intensity distribution (intensity gradient) of activity at ages 17, 19, 21 and 23 were calculated from raw acceleration ActiGraph data and averaged across ages. Hip areal bone mineral density (aBMD), total body bone mineral content (BMC), spine aBMD and hip structural geometry (DXA, Hologic QDR4500A) were assessed at age 23.Valid data, available for 220 participants (124 females),were analysed with multiple regression. To elucidate significant effects, we predicted bone outcomes when activity volume and intensity were high (+1SD), medium (mean),and low (-1SD).

Results:

There were additive associations of volume and intensity with hip aBMD and total body BMC(low-intensity/low-volume cf. high-intensity/high-volume = ∆0.082g·cm-2and ∆169.8g, respectively). or males’ only spine aBMD intensity was associated independently of volume(low-intensity cf. high-intensity = ∆0.049g.cm-2). For hip structural geometry, volume was associated independently of intensity(low-volume cf. high-volume = ∆4.8-6.6%).

Conclusion: The activity profile associated with optimal bone outcomes was high in intensity and volume. The variation in bone health across the activity volume and intensity distribution suggests intensity is key for aBMD and BMC, while high volumes of lower intensity activity may be beneficial for hip structural geometry.

Funding

The authors are grateful to the parents, children, and staff of theIowa Bone Development Study and the Iowa Fluoride Study. The Iowa Bone Development Study was supported by the National Institute of Dental and Craniofacial Research grants R01-DE12101, R01-DE09551, P30-DE10126, R56-DE012101, and the General Clinical Research Centers Program from the National Center for Research Resources, M01-RR00059 and UL1-RR024979.The University of Leicester authors are supported by the NIHR Leicester Biomedical Research Centre, and the Collaboration for leadership in Applied Health Research and Care (CLAHRC) East Midlands. The views expressed are those of the authors and not necessarily those of the NHS, NIHR, or Department of Health.

History

Citation

Medicine and Science in Sports and Exercise (2020) In Press

Version

AM (Accepted Manuscript)

Published in

Medicine and Science in Sports and Exercise

Publisher

Lippincott, Williams & Wilkins

issn

0195-9131

Acceptance date

10/04/2020

Copyright date

2020

Publisher version

TBC

Language

en