Increased Physical Activity at School Benefits Arterial Blood Pressure in Children—A Prospective Follow-Up Cohort Study

(1) Background: A sedentary lifestyle and low physical activity (PA) increase the risk of hypertension in children. The aim of this study was to assess the impact of increased PA at school by elevation of the number of compulsory physical education (PE) lessons on arterial blood pressure in children during a two-year follow-up. (2) Methods: Children (n = 245) born in 2007 attending a standard or elevated number of PE lessons in the school timetable (4 and 10 h a week, respectively) took part in the study. Blood pressure was measured starting from age approx. 10 to 12. (3) Results: Starting from a similar level, after 2 years, the percentage of children with normal blood pressure decreased in the standard-PE children from 83.25% to 78.03% but increased in the elevated-PE ones from 83.15% to 86.13%. The prevalence of both prehypertension and hypertension increased by one-third in the standard-PE children from 16.74% to 21.97% but decreased by one-sixth in the elevated-PE ones from 16.85% to 13.87%. The prevalence of hypertension itself increased by one-third in the standard-PE children from 9.82% to 13.12% but decreased in the elevated-PE ones by one-fifth from 9.60% to 7.75% (4) Conclusions: An increase in PA at school by the elevation of the number of PE lessons benefits children’s arterial blood pressure. Early prevention of hypertension in children can be supported by an adequate number of PE lessons in the school timetable.