Adding more exercise to gym class reduces body fat and blood pressure
As rates of obesity among children and adolescents rise, researchers at the University of North Carolina (UNC) are investigating how changes in physical education classes can combat the problem. Their research, published in the August issue of the
Journal of Adolescent Health
, suggests that increasing the aerobic exercise component and teaching kids about healthy eating and exercise habits may help.
The UNC researchers studied 1140 youths between the ages of 11 and 14 in five rural middle schools in North Carolina. All students participating in the study were in good health with no chronic illnesses or exercise limitations.
Participating students at each school were assigned to one of the following study interventions:
- Exercise only – 30 minutes of aerobic activity, 3 days per week for 8 weeks
- Education only – a class on nutrition, exercise, and smoking, twice per week for 8 weeks
- Exercise and education
- No intervention (control group)
At the start of the study and again at the end of the 8-week program, research assistants measured students’ height, weight, body fat, and blood pressure. Researchers compared the changes in body fat, blood pressure, and body mass index (ratio of weight to height squared) among the four groups.
The control group gained more body fat than any other group, and the exercise-and-education group gained the least amount of body fat. The education-only and exercise-only groups gained less body fat than the control group but more than the exercise-and-education group. In addition, reductions in blood pressure were greatest in the exercise only group, suggesting that exercise alone was responsible for the blood pressure changes.
Overall, increased exercise and health education led to lower body fat and lower blood pressure.
Although these results are interesting and not surprising, this study has its limitations. Because the exercise and education programs only lasted 8 weeks, it’s not clear how they would affect body fat and blood pressure over the long term. In addition, all students from a given school were assigned to the same intervention, so group assignment was not entirely random. The results would be more compelling if students from each school were randomly assigned to each of the four interventions. Finally, the researchers did not measure exercise students were doing outside of the gym class program or any changes in diet–two factors likely to affect the outcome of the study.
This study suggests that increasing the amount of aerobic activity in gym classes and teaching kids about good nutrition and exercise habits may take a “bite” out of the childhood obesity problem. According to the study authors, in some middle schools a 40-minute physical education class involves only 6 to 10 minutes of aerobic exercise for students, so this 30-minute program translates to a major increase in exercise.
Keep in mind, though, children and adolescents are growing, so even among healthy-weight kids weight gain is normal. That’s why this research focused on body fat changes rather than weight changes; in fact, weight gain did not differ significantly across groups. And don’t forget, teaching the children good nutrition habits also seemed to help (at least for eight weeks!).
McMurray RG, et al. A school-based intervention can reduce body fat and blood pressure in young adolescents.
Journal of Adolescent Health.
Last reviewed Aug 7, 2002
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