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J Bone Miner Res. 2016 Nov;31(11):2032-2040. doi: 10.1002/jbmr.2890. Epub 2016 Jul 4.

Longitudinal Trajectories of Television Watching Across Childhood and Adolescence Predict Bone Mass at Age 20 Years in the Raine Study.

Author information

1
School of Physiotherapy and Exercise Science, Curtin University, Perth, Western Australia.
2
Department of Endocrinology and Diabetes, Sir Charles Gairdner Hospital, Nedlands, Australia.
3
School of Medicine and Pharmacology, University of Western Australia, Crawley, Australia.
4
School of Population Health, University of Western Australia, Crawley, Australia.
5
School of Women's and Infants' Health, University of Western Australia, Crawley, Australia.
6
Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada.

Abstract

Sedentary behaviors such as watching television (TV) are associated with increased risk of cardiometabolic disease. The effects of TV watching during key developmental stages on skeletal health are uncertain. Hours of TV watching/week were recorded by parental or self-report at 5, 8, 10, 14, 17, and 20 years of age in 1181 members (48% female) of a pregnancy cohort (the Raine Study). Participants were classified into one of three TV-watching trajectories (using latent class analysis): low (consistently <14 h/week; 20.3%), high (consistently ≥14 h/week; 44.4%), or increasing (increased from <14 to ≥14 h/week during adolescence; 35.3%). General linear models tested associations between TV trajectory and bone mineral content (BMC) measured at age 20 years using dual-energy X-ray absorptiometry. After adjustment for height, body mass, physical activity, calcium intake, serum 25-hydroxyvitamin D levels, alcohol, and smoking (all at age 20 years), males in the low TV-watching trajectory had greater BMC for whole body (mean ± SEM, 3338 ± 59 g versus 3111 ± 31 g), legs (612 ± 12 g versus 569 ± 6 g), and arms (234 ± 5 g versus 214 ± 3 g) than those in the high TV-watching trajectory. Differences between low and high TV-watching trajectories were similar for females. BMC in the increasing TV-watching trajectory also differed for both sexes, for example males in the increasing TV-watching trajectory had greater whole-body BMC (3252 ± 38 g) than males in the high TV-watching trajectory (3111 ± 31 g) but less arm BMC (218 ± 3 g) than those in the low TV-watching trajectory (234 ± 5 g). In this community-based cohort, consistently high TV watching during childhood and adolescence independently predicted reduced peak bone mass at age 20 years. Because attainment of optimal peak bone mass is protective against osteoporosis in later life, reducing sedentary time in children may have long-term skeletal benefits.

KEYWORDS:

BONE MINERAL CONTENT; LONGITUDINAL STUDY; PEAK BONE MASS; RAINE STUDY; TELEVISION

PMID:
27378122
DOI:
10.1002/jbmr.2890
[Indexed for MEDLINE]
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