Objective: To examine long-term effects of leisure time physical activity (ltpa) and occupational physical activity (opa) on later obesity, and to examine the effect of body weight on later physical inactivity in men with and without juvenile onset obesity.
Design: Population-based longitudinal study of obese and nonobese men, who were identified as draftees of median age of 19 y in 1943-77 and later examined at general health surveys in 1982-84, and in 1991-93.
Setting: Copenhagen and adjacent regions, Denmark.
Participants: In all, 1143 juvenile obese men with a BMI > or =31 kg/m2 (corresponding to 35% overweight by an originally used national standard) at draft board examination, and, as a nonobese control group, 1278 men selected as a 0.5% random sample of the approximately 255,600 men examined at the draft board and thus representing the study population.
Main outcome measures: Obesity, defined as BMI > or =30 kg/m2, and physical inactivity at the last survey.
Results: In the cross-sectional analyses, there were strong concurrent inverse associations between ltpa and prevalence of obesity in both groups, whereas there was no relation to opa. In logistic regression analyses of obesity at the last survey, including both ltpa and opa as well as age, BMI at draft board examination, BMI at first follow-up, length of education, smoking and drinking habits, there were no significant effects of ltpa and opa on the risk of development of obesity in the nonobese group or maintenance of obesity in the obese group. Similar analyses of physical inactivity at the last follow-up as outcome showed a significant direct effect of BMI at first follow-up, with a significant trend in the nonobese group, but not in the obese group and no effects on opa.
Conclusion: There is no long-term influence of physical activity on development and maintenance of obesity in men, whereas greater body weight increases risk of later physical inactivity during leisure time.