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Journal of Obesity
Volume 2014 (2014), Article ID 271532, 7 pages
http://dx.doi.org/10.1155/2014/271532
Research Article

Joint Effects of Physical Activity and BMI on Risk of Hypertension in Women: A Longitudinal Study

1Centre for Longitudinal and Life Course Research, School of Population Health, University of Queensland, Herston Road, Brisbane, QLD 4006, Australia
2School of Human Movement Studies, University of Queensland, Blair Drive, St. Lucia, Brisbane, QLD 4072, Australia

Received 8 October 2013; Revised 19 November 2013; Accepted 28 November 2013; Published 23 January 2014

Academic Editor: Yuichiro Yano

Copyright © 2014 Caroline Jackson et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Introduction. There is debate as to whether physical activity counteracts the adverse effect of weight on health outcomes. We investigated how physical activity modifies the effect of body mass index (BMI) on hypertension risk. Methods. BMI, physical activity, and hypertension were measured at baseline and at three-year interval for 14 years (from 1996 to 2010), in 10,339 participants in the Australian Longitudinal Study on Women’s Health. Generalised estimating equation models for binary repeated measures were performed to determine the individual and joint effects of BMI and physical activity on incident hypertension. Results. At baseline (mean age  SD), 57% were healthy weight, 28% overweight, and 14% obese. Increasing BMI and decreasing physical activity were associated with increased risk of hypertension. Physical activity attenuated the positive association between weight and risk of hypertension, especially for obese women. Compared to healthy weight high active women, risk of hypertension in obese high active women was 3.4 times greater (OR 3.43, 95% CI 2.68, 4.39) and in obese inactive women 4.9 times greater (OR 4.91, 95% CI 3.92, 6.13). Conclusions. Both physical activity and maintenance of a healthy body weight are associated with lower risk of hypertension. Physical activity reduced but did not remove the effect of obesity on hypertension risk.