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Bone. 2018 Jul;112:153-160. doi: 10.1016/j.bone.2018.04.011. Epub 2018 Apr 16.

Bone health, activity and sedentariness at age 11-12 years: Cross-sectional Australian population-derived study.

Author information

1
Murdoch Children Research Institute, Parkville, VIC, Australia; The University of Melbourne, Parkville, VIC, Australia.
2
Murdoch Children Research Institute, Parkville, VIC, Australia; The University of Melbourne, Parkville, VIC, Australia; The Royal Children's Hospital, Parkville, VIC, Australia.
3
Murdoch Children Research Institute, Parkville, VIC, Australia; Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Adelaide, SA, Australia.
4
Murdoch Children Research Institute, Parkville, VIC, Australia.
5
Alliance for Research in Exercise, Nutrition and Activity (ARENA), University of South Australia, Adelaide, SA, Australia.
6
Murdoch Children Research Institute, Parkville, VIC, Australia; The University of Melbourne, Parkville, VIC, Australia; Monash University, Clayton, VIC, Australia.
7
ANU Centre for Social Research and Methods, Australian National University, Canberra, ACT, Australia.
8
The George Institute for Global Health, University of Oxford. Oxford, United Kingdom; University of Tasmania, Menzies Institute, Hobart, TAS, Australia.
9
Murdoch Children Research Institute, Parkville, VIC, Australia; The University of Melbourne, Parkville, VIC, Australia; The Burnet Institute, Melbourne, VIC, Australia.
10
Murdoch Children Research Institute, Parkville, VIC, Australia; The University of Melbourne, Parkville, VIC, Australia; The Dept of Paediatrics and Liggins Institute, University of Auckland, New Zealand. Electronic address: melissa.wake@mcri.edu.au.

Abstract

AIM:

To examine cross-sectional associations of children's bone health (size, density, strength) with moderate-vigorous physical activity (MVPA) and sedentary behaviour by considering: (1) duration of activity, (2) fragmentation, and (3) duration/fragmentation combined.

METHODS:

Design: Population-based cross-sectional study.

PARTICIPANTS:

11-12 year-olds in the Longitudinal Study of Australian Children's Child Health CheckPoint. Exposures: MVPA and sedentary behaviour (7-day accelerometry), yielding (1) daily average durations (min/day) and (2) fragmentations (the parameter alpha, representing the relationship between activity bout frequency and bout length).

OUTCOMES:

Tibial peripheral quantitative computed tomography (bone density, geometry, strength).

ANALYSIS:

Multivariable regression models including activity durations and fragmentations separately and combined.

RESULTS:

Of 1357 children attending the CheckPoint, 864 (64%) provided both bone and accelerometry data (mean age 11.4 years (standard deviation (SD) 0.5); 49% male). Mean daily MVPA and sedentary behaviour durations were 34.4 min/day (SD 28.3) and 667.9 min/day (SD 71.9) respectively for boys and girls combined. Each additional daily hour of MVPA was associated with small bone health benefits comprising greater periosteal and endosteal circumference (standardised effect sizes 0.25, 95% CI 0.10 to 0.40 and 0.21, 95% CI 0.03 to 0.39, respectively) and bone strength (0.26, 95% CI 0.14 to 0.38). Sedentary duration and fragmentation of either MVPA or sedentary behaviour showed little association with bone health.

CONCLUSIONS:

In early adolescence, MVPA duration showed associations with better bone health that, while modest, could be of population-level importance. MVPA fragmentation and sedentary behaviour duration and fragmentation seemed less important.

KEYWORDS:

Accelerometry; Adolescents; Bone health; Physical activity; Sedentary behaviour; pQCT

PMID:
29674127
DOI:
10.1016/j.bone.2018.04.011
[Indexed for MEDLINE]

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