In the present study, 2,513 children from the University of Bristol’s Children of the 90s cohort were tracked from age 11 to 24. At the beginning of the study, the children spent an average of six hours per day being sedentary, six hours engaged in light physical activity (LPA), and approximately 55 minutes in moderate-to-vigorous physical activity (MVPA). By the time they reached young adulthood, their daily habits had changed significantly: they spent nine hours per day sedentary, three hours per day in LPA, and about 50 minutes per day in MVPA.

The average blood pressure in childhood was 106/56 mmHg, which increased to 117/67 mmHg in young adulthood, partly due to normal physiological development. A persistent increase in sedentary time from ages 11 to 24 was associated with an average increase of 4 mmHg in systolic blood pressure. Engaging in light physical activity (LPA) from childhood helped to reduce the final blood pressure level by 3 mmHg; however, moderate to vigorous physical activity (MVPA) did not have any effect on lowering blood pressure.

“Moreover, a simulation model indicates that replacing just 10 minutes of sedentary time each hour with an equal amount of light physical activity (LPA) from childhood through young adulthood can lead to a decrease in blood pressure. Specifically, systolic blood pressure could drop by 3 mmHg and diastolic blood pressure by 2 mmHg. This finding is significant because research has shown that a reduction of 5 mmHg in systolic blood pressure can lower the risk of heart attacks and strokes by ten percent,” explains Andrew Agbaje, an award-winning physician and associate professor of Clinical Epidemiology and Child Health at the University of Eastern Finland.

The current study is the largest and the most extended follow-up of accelerometer-measured movement behaviour and blood pressure progression in youth worldwide. Blood pressure measurements, sedentary time, LPA, and MVPA were taken at the ages of 11, 15, and 24. The children’s fasting blood samples were also repeatedly measured for low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, glucose, insulin, and high-sensitivity C-reactive protein. Heart rate, socio-economic status, family history of cardiovascular disease, smoking status as well as dual-energy X-ray absorptiometry measured fat mass and lean mass were accounted for in the analyses.

“We have earlier shown that elevated blood pressure and hypertension in adolescence increase the risk of premature cardiac damage in young adulthood. The identification of childhood sedentariness as a potential cause of elevated blood pressure and hypertension with LPA as an effective antidote is of clinical and public health significance. Several MVPA-based randomised controlled trials in the young population have not lowered blood pressure. We noted an MVPA-induced increase in muscle mass enhanced by a physiologic increase in blood pressure, explaining why earlier MVPA-based randomised clinical trials were unsuccessful,” says Agbaje.

“The World Health Organization estimates that 500 million new cases of physical inactivity-related non-communicable diseases would occur by 2030 and half would result from hypertension. At least three hours of LPA daily is critical to preventing and reversing elevated blood pressure and hypertension. LPA includes long walks, house chores, swimming, and bicycling. We all, parents, paediatricians and policymakers included, should encourage children and adolescents to participate in LPA to keep their blood pressure healthy,” Agbaje concludes.