Overweight children who took part in lifestyle-focused, fitness-oriented gym classes showed significant improvement in body composition, fitness, and insulin levels, according to a study in the October issue of Archives of Pediatrics and Adolescent Medicine, one of the JAMA/Archives journals.

Obesity and poor physical fitness constitute a health problem affecting an increasing number of children. Childhood obesity and poor physical fitness are associated with insulin resistance, type 2 diabetes mellitus, blood lipid abnormalities, and high blood pressure in later life, according to background information in the article. The causes of childhood obesity include a pervasive "toxic" environment that facilitates increased caloric intake and reduced physical activity. In order to alter the children's environment, the authors suggest, an effective strategy for prevention and treatment of childhood obesity must be pervasive and collaborative. The school setting is an attractive starting point for a collaborative effort.

Aaron L. Carrel, M.D., and colleagues at the University of Wisconsin, Madison, conducted a randomized, controlled study to determine whether a school-based fitness program can improve body composition, cardiovascular fitness level, and insulin sensitivity in overweight children. Fifty overweight middle school children were randomized to lifestyle-focused, fitness-oriented gym classes (the treatment group) or standard gym classes (the control group) for nine months. The children were evaluated for fasting insulin and glucose levels, body composition, and maximum oxygen consumption treadmill testing before the school year, and at the end of the school year. There were no differences in age, body mass index, or sex distribution between the groups at baseline.

Fitness-oriented gym classes were designed to make fitness and good nutrition fun and achievable and to maximize the amount of movement during the class period. Class size was limited to 14 students to allow for increased instructor attention, increased opportunity for motivation, and less time standing in line.

"Children enrolled in fitness-oriented gym classes showed greater loss of body fat, increase in cardiovascular fitness, and improvement in fasting insulin levels than control subjects," the authors report.

The authors say the study results suggest that school curricula may be an effective vehicle for increasing physical activity and improving cardiovascular health for children, and they believe further study is warranted. "In this study, even a small change in the amount of physical activity showed beneficial effects on body composition, fitness, and insulin levels in children. Similar benefits have been shown by lifestyle improvements in adults with known glucose intolerance," they write.

The authors emphasize that it is important to develop and evaluate interventions designed to start in childhood, because childhood obesity is predictive of adult obesity. They suggest partnering with school districts should be part of a public health approach to improving the health of overweight children.

"These findings should help to encourage the development of physical education programs that are effective in providing children with substantial amounts of physical activity," they conclude. "Clearly, however, an effective public health approach must promote increased physical activity inside and outside of school, as physical activity recommendations cannot be met through physical education alone." (Arch Pediatr Adolesc Med. 2005;159:963-968. Available pre-embargo to the media at http://www.jamamedia.org.)