Risk of obesity in relation to physical activity tracking from youth to adulthood.

PURPOSE: Maintaining a high level of physical activity throughout one's lifetime may decrease the risk of obesity. We evaluated how physical activity patterns from youths (9-18 yr) to adulthood are associated with body mass index (BMI) and waist circumference (WC) in a population of young adults.

METHODS: As part of the longitudinal Cardiovascular Risk in Young Finns Study, we assessed physical activity over a 21-yr follow-up in a cohort of 1319 subjects. Physical activity was measured using a questionnaire completed in conjunction with a medical examination.

RESULTS: During the follow-up, 33.1% of men and 32.0% of women were classified as persistently active, and 11.5% of men and 7.4% of women as persistently inactive. Both decreasingly active and persistently inactive subjects were more likely to be obese as adults compared with persistently active subjects. In women, being decreasingly active from youth to adulthood compared with being persistently active was independently associated with the risk of being overweight (BMI = 25.0-29.9 kg.m(-2), odds ratio (OR) = 2.35, confidence interval (CI) = 1.16-4.78), obese (BMI > or = 30.0 kg.m(-2), OR = 2.72, CI = 1.04-7.09), mildly abdominally obese (WC = 800-879 mm, OR = 2.21, CI = 1.01-4.84), and severely abdominally obese (WC > or = 880 mm, OR = 2.19, CI = 1.03-4.67), after adjustment for several variables including childhood fatness. In men, decreasing physical activity during their lifetime was associated with mild (WC = 940-1019 mm, odds ratio (OR) = 1.78, CI = 1.00-3.19) and severe (WC > or = 1020 mm, OR = 2.47, CI = 1.27-4.78) abdominal obesity in unadjusted analyses, but these two associations disappeared after adjustment for confounding variables (OR = 1.51, CI = 0.72-3.17 and OR = 1.62, CI 0.66-4.02, respectively). In men, changes in physical activity were not associated with obesity or overweight as defined by cut-points of BMI.

CONCLUSIONS: Maintaining a high level of physical activity from youth to adulthood is independently associated with lower risk of abdominal obesity in among women, but not men. These findings suggest that changes in physical activity patterns during the lifetime may contribute to the development of abdominal obesity in women.