Exercising less during childhood and young adulthood linked to higher C-reactive protein
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Key takeaways:
- Children and young adults with more sedentary time have higher C-reactive protein levels.
- Light physical activity may be better for reducing inflammation than moderate to vigorous exercise.
Children and young adults who have longer sedentary time are more likely to have high C-reactive protein levels, an indicator of greater inflammation, according to study findings.
“From this study, we learned that sedentary behavior from childhood may independently contribute to increased inflammation even after accounting for several cardiometabolic risk factors,” Andrew Agbaje, MD, MPH, clinical researcher in the Institute of Public Health and Clinical Nutrition, School of Medicine at University of Eastern Finland, and honorary research fellow at the Children’s Health and Exercise Research Center in the department of public health and sports sciences at the University of Exeter in the U.K., told Healio. “Unfortunately, sedentary behavior increased from 6 hours per day to 9 hours per day during growth from childhood to young adulthood. Likewise, light physical activity decreased from almost 6 hours per day to about 3 hours per day, but moderate to vigorous physical activity was roughly constant. So sedentary behavior is indeed replacing light physical activity, which could be detrimental to health.”
Agbaje obtained data from 792 people who were born in the U.K. from April 1991 to December 1992. Sedentary time, light physical activity and moderate to vigorous physical activity were measured with an accelerometer at age 11, 15 and 24 years. High-sensitivity C-reactive protein (CRP) was assessed at age 15, 17 and 24 years. Researchers collected anthropometric data, body composition, heart rate, blood pressure and fasting insulin at age 11, 15 and 24 years. Fasting plasma glucose, cholesterol and triglycerides were assessed at age 15, 17 and 24 years.
The study was published in The Journal of Clinical Endocrinology & Metabolism.
The study group had an increase in sedentary time and decrease in light physical activity time from age 11 to 24 years. Time spent performing moderate to vigorous physical activity declined from age 11 to 15 years before increasing at age 24 years.
Greater sedentary time was associated with higher CRP. Insulin resistance, LDL and HDL cholesterol partly suppressed the association, whereas increases in systolic BP and lean mass partly mediated the association. Among participants with normal weight, insulin resistance suppressed the link between sedentary time and CRP by 2.8%. Among those with overweight or obesity, the association was 28.9% mediated by total body fat mass, 7% mediated by lean mass and 23.5% suppressed by insulin resistance.
Participants who spent more time performing light physical activity had lower CRP. Total body fat mass partly mediated the association for the full study population. Among participants with normal weight, total body fat mass mediated the association by 20.6%. There were no mediating or suppressing factors for those with overweight or obesity.
Greater moderate to vigorous physical activity was associated with lower CRP in the study group, with total body fat mass mediating the association. Among those with normal weight, total body fat mass mediated the association by 53.5% and lean mass mediated it by 7%. No mediating effect was observed for people with overweight or obesity.
“The significant reduction of the effect of moderate to vigorous physical activity in lowering inflammation as a result of increased fat mass even in normal weight children and adolescents is surprising,” Agbaje said. “It is physiological to increase fat mass during growth, but the near-total neutralization effect of fat mass on moderate to vigorous physical activity is rather novel.”
Agbaje said the study revealed how increased moderate to vigorous physical activity may not work for all people due to the potential for increased fat mass and how excess vigorous physical activity could lead to organ damage.
“Light physical activity seems to yield unrestricted health benefits, but would require more hours to acquire, for instance, 3 hours per day,” Agbaje said. “Public health messages, recommendations and emphasis should now shift to light physical activity, which potentially holds tremendous health benefits.”
Agbaje said more studies are needed to analyze the impact of light physical activity on cardiometabolic health among children and young adults, as well as across more diverse populations.
For more information:
Andrew Agbaje, MD, MPH, can be reached at andrew.agbaje@uef.fi.
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