“Sedentariness should be recognized as one of the 21st-century independent causes of excess insulin, fat obesity, high lipid levels, inflammation, and arterial stiffness,” says Andrew Agbaje, MD, PhD, associate professor of clinical epidemiology and child health at the University of Eastern Finland. In collaboration with the Universities of Bristol and Exeter in England, Agbaje researched the effects of sedentariness on childhood health, especially in relation to insulin and insulin resistance. The results were published in March in The Journal of Clinical Endocrinology and Metabolism.
Agbaje based his research on the University of Bristol’s Avon Longitudinal Study of Parents and Children (ALSPAC), also known as Children of the ’90s, which followed over 14,000 people for more than 25 years. Data on the participants’ health was collected over that time via questionnaires, clinical assessments, and biological samples. For the new study, Agbaje focused on 792 participants who provided valid sedentary time (ST), light physical activity (LPA), and moderate to vigorous physical activity (MVPA) measurements by wearing accelerometer devices on their waists for 4–7 days at ages 11, 15, and 24.
The participants also provided blood samples at ages 15, 17, and 24 years, which were measured for fasting insulin, glucose, high-density lipoprotein, low-density lipoprotein, triglycerides, and high-sensitivity C-reactive protein. Blood pressure, heart rate, smoking status, socio-economic status, and family history of cardiovascular disease were all controlled for in the analyses.
At baseline, the children spent an average of 6 hours per day in ST, which increased to 9 hours per day during the later follow-up. This increase in sedentary time was associated with continuously higher insulin levels in fasting blood, especially among youths who were overweight and obese, whose risk of excess insulin increased by 20%. On the other hand, children with LPA measures of 3-4 hours per day throughout the follow-up saw their risk of excess insulin decrease by 20%. Higher LPA was also associated with lower insulin resistance. MVPA also showed signs of reducing insulin but to a much smaller extent.
Conclusions
Agbaje’s study is the largest and the longest follow-up accelerometer-measured movement behavior and glucose, insulin, and insulin resistance study in the world. And the results are concerning, he says. “[We] have identified childhood sedentariness as a monster that threatens the young population across the globe, no thanks to excessive screen use.”
The good news is that light physical activity can counteract the effects of sedentariness and decrease the risk of developing diabetes and other chronic diseases. “Promoting LPA while decreasing body fat mass and ST may be considered crucial intervention targets to attenuate the risk of dysglycemia, hyperinsulinemia, and insulin resistance from childhood through young adulthood,” Agbaje wrote in his study’s conclusion,” adding later that “public health experts, health policymakers, health journalists, pediatricians, and parents should encourage kids to participate in LPA daily.”
