April 28 (UPI) -- A study by the University of Bristol in England found that there is a decline in children's physical activity levels as they age and progress through school.
Researchers found that children spent less time doing physical activity and were more sedentary from the first year of primary or elementary school, between age 5 and 6, to the fourth year of school at age 8 and 9.
By age 8 and 9, one-third of boys and two-thirds of girls were failing to meet Chief Medical Officer's, or CMO, guidelines of an hour of physical activity each day, researchers report.
Bristol researchers used accelerometers to track the level of physical activity of 1,299 children at 57 primary schools in England, at the beginning of the study. About 47 schools and 1,223 children and parents were retested at the four-year mark, with the children and at least one parent wearing an accelerometer for five days.
Multiple imputation was used to account for the 1,837 families who initially took part but did not participate in the follow-up study.
Researchers found levels of moderate-to-vigorous-intensity physical activity dropped by 4 percent in boys and 11 percent in girls during the study period. The amount of sedentary time also increased by 20 percent in boys and 23 percent in girls.
Approximately 72.5 percent of boys and 53.7 percent of girls met the CMO's guidelines of one hour of physical activity per day in the first year, but that number dropped to 62.3 percent of boys and 35 percent of girls by year four.
"The results show a clear need to find ways to help children to be active throughout the primary school years," Russell Jago, professor of Pediatric Physical Activity and Public Health at the University of Bristol, said in a press release. "We need to get children active and then keep them active as they more through primary school."