Arnold School study: Children’s respiratory fitness levels are lowered by increased screen time
June 11, 2012
Cardiorespiratory fitness (CRF) levels could be increased in childhood if less time is spent in front of electronic screens, according to a study published in the official journal of the American College of Sports Medicine.
Led by researchers at the Arnold School of Public Health, the study is published in the June edition of Medicine & Science in Sports & Exercise®. It shows an important negative effect of sedentary behavior in childhood.
“In this technology age, children spend more time in sedentary behavior,” said the study’s lead author, Dr. Jonathan Mitchell, who conducted the research while pursuing his doctoral degree at the Arnold School. “We wanted to see if high screen-based sedentary behavior affected CRF levels in childhood, and if this effect was independent of physical activity levels.”
The research team assessed the relationship between time spent in screen-based sedentary behavior and changes in CRF. More than 2,000 children were followed from ages 11 to 13, and each child self-reported their screen time and completed a shuttle-run test to provide a measure of their CRF level. Importantly, the authors adjusted for time spent in high-intensity physical activity.
Children who reported more screen time completed fewer shuttle-run laps between ages 11 and 13. The association was strongest for the children who had mid-to-high CRF levels, and was independent of physical activity levels. If instances of sedentary behavior are lowered in children, it is predicted that CRF levels would increase, said Mitchell, a postdoctoral fellow at the Center for Clinical Epidemiology and Biostatistics at the University of Pennsylvania.
“The results are interesting and add to the evidence that spending too much time sitting is hazardous to children’s health,” said Mitchell. “If children limit the amount of time spent sitting in front of a screen, then this could help to combat declining levels of cardiorespiratory fitness in youth.”
Mitchell completed his bachelor’s degree in physiology and his master’s degree in human nutrition from the University of Glasgow in Scotland. He is the recipient of a Ruth L. Kirschstein National Research Service Award (NRSA) from the National Institutes of Health.
Drs. Steve Blair and Russ Pate of the Arnold School were co-authors on the paper.