Relationship Among Body Mass Index, Physical Activity, Sedentary Behavior, and Blood Pressure in Portuguese Children and Adolescents: A Cross-Sectional Study

This study examined the associations between age, adiposity, physical activity, sedentary behavior, and elevated blood pressure (BP) in 2901 Portuguese children and adolescents aged 2–18. BP, body mass index (BMI), waist-to-height ratio (WHtR), physical activity, and sedentary behavior were measured. Elevated BP was defined as a BP above the 90th percentile for age, sex, and height. Multivariable analyses assessed the prevalence ratios (PR) of elevated BP across age groups, BMI, WHtR, physical activity, and sedentary behavior. Results showed that older age, especially among middle schoolers, was associated with a 1.8 times higher risk of elevated BP than preschoolers. Participants with a higher BMI (overweight/obese) and a WHtR ≥ 0.50 had a 1.49- and 1.4-times higher risk of elevated BP, respectively. Those who did not meet the recommended 60 min of moderate-to-vigorous physical activity (MVPA) per day showed a 1.63 times higher risk of elevated BP, whereas the association between sedentary behavior and BP was not significant after adjustment. These findings highlight age, higher BMI, central obesity, and insufficient physical activity as key factors associated with elevated BP, underscoring the need for early monitoring and intervention to prevent hypertension in this population.