The Association between Physical Activity and Metabolic Risk Factors in Adolescents with Different Levels of Sedentary Time

Abstract

Adolescents with greater sedentary time are more likely to have elevated metabolic risk factors. On the other hand, physical activity (PA) is inversely associated with metabolic risk in adolescents. A better understanding of how these variables interact with adolescent metabolic health is important to identify if the benefits of PA are present in adolescents with different levels of sedentary time. PURPOSE: To identify association between PA and metabolic risk factors in adolescents with different levels of sedentary time METHODS: A cross-sectional study was conducted on 941 adolescents (411 males) aged 12 to 17 from public schools in Curitiba, Brazil. Fasting blood glucose, Total Cholesterol, LDL-cholesterol, HDL-cholesterol, Triglycerides, Waist Circumference (WC) were determined by z-scores and z-cores inversely calculated for HDL-cholesterol where high values indicated low levels of this variable. The sum of z-scores indicated a total metabolic risk score. The Adolescent Sedentary Activity Questionnaire measured the daily time spent with sedentary activities. The adolescents were divided in three groups according to their sedentary behavior (Low, Moderate and High sedentary time). The International Physical Activity Questionnaire - Short version verified the time spent in moderate to vigorous physical activity (MVPA). Partial correlations, controlled by Sex, BMI Status and Biological maturation, verified relationship between MVPA and metabolic risk factors for each group of sedentary time. RESULTS: SSignificant associations between MVPA and metabolic risk factors in Low sedentary time group was only shown for waist circumference (r= -.122; p=.037). In Moderate sedentary time group, MVPA was inversely associated with Fasting blood glucose(r= -.145; p= .015), HDL-cholesterol (r= -.161; p= .007) and Metabolic risk score (r= -.162; p= .006). There was no associations between MVPA and metabolic risk factors in the High sedentary time group. CONCLUSIONS:MVPA related inversely to metabolic risk factors only in Low and Moderate sedentary time groups. MVPA related to WC in the first group and to Fasting blood glucose, HDL-cholesterol and Metabolic risk score in the second group. It seems to exist a moderator influence of sedentary time in associations between MVPA and metabolic risk factors.