By cutting the time adolescents spend standing around in school physical education classes and boosting the amount of exercise they do, University of North Carolina at Chapel Hill experts have shown they can control the children’s body fat and lower their blood pressure.
Positive results are measurable within eight weeks of regularly scheduled classes, researchers say.
Their new study — the first to show such benefits from physical education classes for adolescents — revealed that each class involved as few as six to 10 minutes of vigorous exercise, at least in the schools they worked with. Without much difficulty, researchers tripled exercise time by substituting activities that kept the children in motion and not just watching others.
“Having children participate in vigorous exercise programs while simultaneously learning about the benefits of proper nutrition and exercise reduces their chances of ultimately developing type 2 diabetes and other health problems associated with inactivity and being overweight,” said Dr. Robert G. McMurray, professor of exercise and sport science at UNC. “As a group, active children of normal weight will live significantly longer, healthier and more satisfying lives. As a nation, we need to emphasize this much more since right now, we’re doing an increasingly bad job of it.”
A report on the findings appears in the August issue of the Journal of Adolescent Health. Besides McMurray, authors are Dr. Joanne S. Harrell, professor of nursing at the UNC School of Nursing, Chrysse Bradley, research associate with the Carolina Population Center; and Shibing Deng, statistician in nursing. Other authors are Drs. Shrikant I. Bangdiwala, research associate professor of biostatistics at the UNC School of Public Health, and Amy Levine, clinical assistant professor of pediatrics at the UNC School of Medicine.
Because they found in an earlier project the beginnings of high blood pressure among N.C. elementary school students, the researchers studied 1,140 11- to 14-year old middle school children, including 630 girls and 510 boys in four state school systems, McMurray said. They randomly assigned students to four “treatment” groups – added exercise only, education only, exercise and education combined and a control group, which received no extra push in physical education.
“We wanted to see whether we could modify the children’s programs slightly, stay within the state-mandated curriculum and still make a difference in terms of their risk profiles,” he said. “Among the things we knew were that diets in central and eastern North Carolina – like many parts of the country — tend to be high in fat and that physical activity of rural children is less than that of children from urban areas.”
Researchers found all four groups grew normally in height and all four, as expected, grew heavier over the two-month period studied, McMurray said. However, skin fold tests of the control group children showed they put on three times as much body fat as the other children who exercised and learned more about the lasting importance of vigorous exercise and good eating habits.
Skin fold and blood pressure measurements for children in the exercise-only groups fell between the two extremes, he said. Education-only groups did not differ significantly from the control group, suggesting that exercise was the most important component of the improved classes.
“With the blood pressure testing, we found drops in both systolic and diastolic pressures of four millimeters of mercury in the children who did more exercise and also learned about good nutrition,” McMurray said. “Although that’s not a big drop, it’s pretty significant since it happened over only two months and with kids who were going through puberty. With both measures, we found more of a benefit than we expected.”
Keeping blood pressure at healthy levels is important since it naturally increases as adolescents age into adulthood, and high blood pressure is a significant risk factor for heart disease, stroke, heart attack and other serious conditions, he said. Controlling obesity cuts the risk of type 2 diabetes, which has risen alarmingly in American children over the past few decades.
The new study is not the first to examine the effects of physical education classes, but it is the first to show significant improvements in skin fold and blood pressure tests among older children getting more exercise in such classes, McMurray said. The chief reason seems to that he and his colleagues boosted the amount of exercise they asked children to do more than their colleagues had.
“Schools are looking for ways to improve children’s academic test scores, and many have either reduced or eliminated physical education,” he said. “Now physical education might not result in brighter kids, but it will produce more productive adults who face fewer health threats and health-care costs down the road.”