Light physical activity emerges as powerful tool to reverse childhood inactivity's cholesterol risk

Increased sedentary time in childhood can raise cholesterol levels by two thirds as an adult, leading to heart problems and even premature death - but a new study has found light physical activity may completely reverse the risks and is far more effective than moderate-to-vigorous physical activity.

The study was conducted in collaboration between the University of Exeter, University of Eastern Finland, and University of Bristol and published in The Journal of Clinical Endocrinology & Metabolism. Researchers used data from the University of Bristol study Children of the 90s (also known as the Avon Longitudinal Study of Parents and Children), which included 792 children aged 11 years who were followed up until the age of 24.

Results from this study found that accumulated sedentary time from childhood can increase cholesterol levels by two thirds (67 percent) by the time someone reaches their mid-twenties. Elevated cholesterol and dyslipidaemia from childhood and adolescence have been associated with premature death in the mid-forties and heart problems such as subclinical atherosclerosis and cardiac damage in the mid-twenties.

Healthy lifestyles are considered important in the prevention of dyslipidaemia and one of the primary ways of lowering cholesterol, apart from diet, is movement behaviour. For the first time, this study objectively examined the long-term effects of sedentary time, light physical activity, and moderate-to-vigorous physical activity on childhood cholesterol levels.

The World Health Organization currently recommends children and adolescents should accumulate on average 60 minutes of moderate-to-vigorous physical activity a day and reduce sedentary time but have limited guidelines for light physical activity. Yet this new study and other recent studies has found light physical activity – which includes exercises such as long walks, house chores, or slow dancing, swimming, or cycling – is up to five times more effective than moderate-to-vigorous physical activity at promoting healthy hearts and lowering inflammation in the young population.

Dr Andrew Agbaje from the University of Exeter led the study and said: "These findings emphasise the incredible health importance of light physical activity and shows it could be the key to preventing elevated cholesterol and dyslipidaemia from early life. We have evidence that light physical activity is considerably more effective than moderate-to-vigorous physical activity in this regard, and therefore it's perhaps time the World Health Organization updated their guidelines on childhood exercise - and public health experts, paediatricians, and health policymakers encouraged more participation in light physical activity from childhood."

During the research, accelerometer measures of sedentary time, light physical activity, and moderate-to-vigorous physical activity were collected at ages 11, 15, and 24 years. High-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, and total cholesterol were repeatedly measured at ages 15, 17, and 24 years. These children also had repeated measurement of dual-energy Xray absorptiometry assessment of total body fat mass and muscle mass, as well as fasting blood glucose, insulin, and high sensitivity C-reactive protein, with smoking status, socio-economic status, and family history of cardiovascular disease.

During the 13-year follow-up, sedentary time increased from approximately six hours a day to nine hours a day. Light physical activity decreased from six hours a day to three hours a day while moderate-to-vigorous physical activity was relatively stable at around 50 minutes a day from childhood until young adulthood. The average increase in total cholesterol was 0.69 mmol/l. It was observed without any influence from body fat.

An average of four-and-a-half hours a day of light physical activity from childhood through young adulthood causally decreased total cholesterol by (-0.53 mmol/l), however, body fat mass could reduce the effect of light physical activity on total cholesterol by up to six percent. Approximately 50 minutes a day of moderate-to-vigorous physical activity from childhood was also associated with slightly reduced total cholesterol (-0.05 mmol/L), but total body fat mass decreased the effect of moderate-to-vigorous physical activity on total cholesterol by up to 48 percent. Importantly, the increase in fat mass neutralised the small effect of moderate-to-vigorous physical activity on total cholesterol.

The paper is entitled Associations of Sedentary Time and Physical Activity from Childhood with Lipids: A 13-Year Mediation and Temporal Study and published in The Journal of Clinical Endocrinology & Metabolism. These findings come shortly after another study led by Dr Andrew Agbaje published this week in Nature Communications found light physical activity may completely reverse childhood obesity linked to increased sedentary time in more than 6000 children. Sedentary time contributed seven to ten percent of the total fat mass gained during growth from childhood until young adulthood. Light physical activity decreased the overall gain in fat mass by 9.5–15 percent, while moderate-to-vigorous physical activity decreased fat mass by 0.7–1.7 percent.

Our research suggests light physical activity may be an unsung hero and it is about time the world replaced the mantra of 'an average of 60 minutes a day of moderate-to-vigorous physical activity' with 'at least 3 hours a day of light physical activity'. Light physical activity appears to be the antidote to the catastrophic effect of sedentary time in the young population."

Dr Andrew Agbaje, University of Exeter

Dr Andrew Agbaje's research group (urFIT-child) is supported by research grants from Jenny and Antti Wihuri Foundation, the Finnish Cultural Foundation Central Fund, the Finnish Cultural Foundation North Savo Regional Fund, the Orion Research Foundation, the Aarne Koskelo Foundation, the Antti and Tyyne Soininen Foundation, the Paulo Foundation, the Yrjö Jahnsson Foundation, the Paavo Nurmi Foundation, the Finnish Foundation for Cardiovascular Research, Ida Montin Foundation, the Foundation for Pediatric Research, and Alfred Kordelin Foundation.