Increased sedentary time in children as they grow into adulthood causes significant heart damage that could put them at an increased risk of heart attack and stroke in later life, a new study has found.
Researchers found that a lack of physical activity in adolescence increases heart mass, leading to long-term impacts on the heart’s structure and function.
The findings, published in the European Journal of Preventive Cardiology, show that encouraging even light physical activity in children can positively impact their future heart health and reduce the risk of premature heart damage.
Increasing levels of physical activity are known to improve cardiometabolic and vascular health among young people. This has led to the recommendation that children under 18 undertake an average of 60 minutes of moderate-to-vigorous-intensity physical activity daily.
However, there is limited research showing how sedentary time and physical activity affect changes in heart structure and function over time in children.
To address this issue, researchers from the Universities of Exeter, Bristol and Eastern Finland analysed data from 1,682 children and young people who are part of the University of Bristol’s Children of the 90s cohort.
Activity levels were measured using accelerometer devices at ages 11, 15 and 24, including time spent sedentary or engaged in light-intensity physical activity or moderate-to-vigorous-intensity physical activity.
The researchers examined changes to their cardiac structural and functional properties during growth until young adulthood through echocardiography measurements at ages 17 and 24.
Blood samples were also measured for markers of cardiovascular risk including low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, glucose, insulin, and high-sensitivity C-reactive protein. Blood pressure, heart rate, smoking status, socio-economic status, family history of cardiovascular disease, and dual-energy X-ray absorptiometry measured fat mass and lean mass were accounted for in the analyses.
At age 11, the children spent an average of six hours per day in sedentary activities, which increased to nine hours per day by young adulthood. The researchers found this significant increase in sedentary time contributed 40% of the total increase in heart mass seen in participants from ages 17 to 24.
The results were similar in children and adolescents with either normal weight or overweight and obesity, and in children with either normal blood pressure or high blood pressure.
However, the increase in cardiac mass was reduced on average by almost half (49%) over the seven-year observation period due to light physical activity. This involved participation in activities such as walking, cycling, playing in the playground and gardening for at least three hours per day, combined with decreasing sedentary time.
In comparison, for each additional minute of moderate-to-vigorous physical activity during childhood, the researchers found a five% increase in cardiac mass out of the total expected increase occurring between adolescence and young adulthood.
They say their findings show that sedentary time contributes eight times more to increased cardiac mass than moderate-to-vigorous physical activity, the latter of which is associated with physiological increase.
The researchers suggest that childhood sedentariness causes increased body fat, inflammation, blood pressure, lipid levels, arterial stiffness, and subsequent cardiac enlargement, which leads to poor heart health later in life.
Professor Andrew Agbaje of the University of Exeter Children’s Health and Exercise Research Centre said: ‘Childhood sedentariness is a ticking time bomb, and tackling the problem should be a public health priority. Light physical activity is the only effective antidote against sedentariness and it’s fairly easy to accumulate three to four hours a day.’
Professor Agbaje added: ‘There should be a political will at local, national, and global levels to promote light physical activity. We need to act now because the economic and health cost of sedentariness may become unbearable. Public health experts, health policymakers, paediatricians, and parents should encourage kids to participate in daily light physical activity straight away.’
