Leisure-Time Physical Activity And Cardiovascular Risk Factors In Adolescents

Abstract

Associations between leisure-time physical activity and cardiovascular risk factors are generally weak in observational studies in adolescents. PURPOSE: To study associations between leisure-time physical activity and blood lipids, lipoproteins and blood pressure in 13-year-old boys and girls. METHODS: This study is a part of the large prospective randomized STRIP study (Special Turku Coronary Risk Factor Intervention Project) on-going in Turku, Finland. In infancy, the children (n=1062) were randomized to an intervention group with regular dietary and lifestyle counselling and to a control group. Leisure-time physical activity habits were assessed during a study visit at age 13 by a self-reported questionnaire. Leisure-time physical activity index (PAI; MET h/wk) was calculated by multiplying mean leisure-time exercise intensity, duration and frequency (n=544). According to PAI, the girls and boys were divided into 3 groups and the least and most active groups were compared: 1) Sedentary, mean PAI 3.2 MET h/wk for intervention girls (n=39) and 3.1 for control girls (n=48), 8.6 for intervention boys (n=46) and 8.0 for control boys (n=64), 2) Active, mean PAI 56.3 MET h/wk (n=27) and 53.2 (n=26) for girls, 58.0 (n=49) and 59.7 (n=41) for boys, respectively. Cardiovascular risk factors included total cholesterol, HDL, HDL/total cholesterol ratio, LDL, triglyceride, systolic and diastolic blood pressure. ANCOVA with BMI and pubertal status as covariates was used to test differences in cardiovascular risk factors between the PAI groups. RESULTS: In the dietary counselling groups, HDL was higher in physically active boys than in sedentary boys (mean 1.24 vs. 1.13 mmol/L, adjusted p=0.034). In the control groups, HDL and HDL/total cholesterol ratio were higher in physically active girls than in sedentary girls (mean 1.29 vs. 1.16 mmol/L, adjusted p=0.021 and 0.31 vs. 0.27, adjusted p=0.0076, respectively). No other differences between groups were found. CONCLUSION: Cross-sectional associations between leisure-time physical activity and cardiovascular risk factors are weak and inconsistent in 13-year-old adolescents. However, it remains to be seen if this longitudinal study is able to find possible relationships in the future.