Association between physical activity level and blood pressure: varied and graded mediating effects of obesity indices in schoolchildren

Abstract

AbstractObjective:To explore the mediating effects of adiposity indices in the association between physical activity level and blood pressure in a Nigerian schoolchildren population.Materials and Methods:One thousand five hundred and seventeen schoolchildren (714 males and 803 females) from randomly selected primary schools participated. Physical activity level, sum of skinfold thickness at three sites, waist circumference, body mass index, and blood pressure were measured using standardised procedures. The statistical significance of the mediating effects of adiposity indices was determined using Sobel Test.Results:Some obesity indices mediated the association between physical activity level and systolic blood pressure [males: waist circumference (t = 5.31; p < 0.001), skinfold thickness (t = 3.80; p < 0.001), and waist circumference/height (t = 2.21; p < 0.001); females: body mass index (t = 8.03; p < 0.001), waist circumference (t = 7.80; p < 0.001), and skinfold thickness (t = 5.94; p < 0.001)]. Similarly, some obesity indices mediated the prediction of diastolic blood pressure in females [males: body mass index (t = 1.95; p = 0.05), waist circumference (t = 2.65; p = 0.01), and skinfold thickness (t = 1.97; p = 0.05); females blood pressure: body mass index (t = 6.49; p < 0.001), waist circumference (t = 6.29; p < 0.001), skinfold thickness (t = 2.31; p = 0.02), and waist circumference/height (t = 2.59; p = 0.01)].Conclusion:The obesity indices that mediate the association between physical activity level and blood pressure vary, and their mediating effects are graded. While waist circumference and skinfold thickness exert the greatest mediating effects on the association in males, body mass index and waist circumference do in females.