Public health aspects of physical activity

In this thesis different public health aspects of physical activity in the Netherlands were addressed, taking into account its broad scope. Research was carried out on physical activity methodology, determinants of physical activity and the relationship between physical activity and different health outcomes. As to physical activity methodology, we established reproducibility and relative validity of the short questionnaire to assess health enhancing physical activity (the SQUASH). With regard to determinants of physical activity, we found that adherence to the Dutch physical activity guideline was inversely associated with the cognitive attitude towards increasing physical activity and positively with self efficacy and the perception of having sufficient affordable exercise facilities in the neighbourhood. Results of another study showed that the time people spent on walking and bicycling was associated with the square area of green and recreational space close to their home.Concerning the relationship between physical activity and health outcomes we performed a meta-analysis on 31 observational studies addressing the association between physical activity and stroke. The results of this meta-analysis indicated an inverse association between physical activity and stroke risk with a 25-40% lower risk of stroke among those who were physically active. This association was stronger in</span><st1:place><span lang=EN-GB>Europe</span></st1:place><span lang=EN-GB>than in the</span><st1:country-region><st1:place><span lang=EN-GB>USA</span></st1:place></st1:country-region><span lang=EN-GB>. Furthermore, we studied the association between physical activity, body mass index and 12-year cardiovascular mortality in a cohort of 35,650 healthy Dutch men and women aged 20-59 years at baseline. Results showed that especially inactive, obese individuals were at high risk of coronary heart disease (HR: 3.1; 95%CI: 1.3-7.6), stroke (HR: 4.8; 95%CI: 1.1-20.7), as well as cardiovascular diseases mortality (HR: 3.2; 95%CI: 1.7-6.0) compared with very active, normal weight individuals. Finally, we studied cross-sectional and longitudinal associations between physical activity and health-related quality of life among 1,871 men and women aged 26-65 at baseline. Cross-sectional associations were not confirmed by longitudinal analyses. Cross-sectional associations were mainly found for physical components of health-related quality of life, whereas longitudinal associations were predominantly observed for mental components of health-related quality of life.The research described in this thesis emphasises the large public health potential of physical activity. In our general discussion we argued that the present situation on physical inactivity in the Netherlands makes it crucial for researchers and policy maker