Background: Physical activity (PA) is a well know modifiable risk factor for prevention of hypertension and obesity. However, optimal patterns of accrual of recommended levels of PA to prevent hypertension and obesity are not known. The aim of this study was to investigate the associations of PA volume, frequency and intensity with incidence of hypertension and obesity over 15 years in Australian women.
Methods: Data from the ‘young cohort’ and ‘mid cohort’ (aged 18-23y and 45-50y in 1996, respectively) of the Australian Longitudinal Study of Women’s Health were used (N=20,588). Self-reported PA, hypertension, height, and weight were collected using mail surveys every three years from 2000 to 2015. Cox proportional hazard models were used to investigate the association of PA volume (None; 33-499; 500-999; 1000+ MET.minutes/week), weekly frequency (None; 1-2; 3-4; 5-7; 8+) and the proportion of vigorous PA to total volume of PA (None; 0%; 1-33%; 34-66%; 67-100%) with incidence of hypertension and obesity from 2000 to 2015.
Results: Over 15 years, cumulative incidence of hypertension was 6.6% in young and 21.7% in the mid cohort (~1 and 5 new cases per 100 women every three years in the young and mid cohort, respectively). Nearly 15% of women in each cohort developed obesity in 15 years since. Overall, higher volume of PA was associated with reduced risks of hypertension and obesity. When volume of PA was considered, the risk of hypertension did not vary according to frequency or intensity of PA. However, increased frequency and proportion of vigorous PA to total volume of PA were both associated with reduced risk of obesity.
Conclusion: In this large population-based cohort of Australian women, PA volume was associated with lower incidence of hypertension and obesity. Incorporating more sessions of PA, particularly of vigorous intensity might add extra benefits for prevention of obesity.