School-based exercise improves fitness, body composition, insulin sensitivity, and markers of inflammation in non-obese children.

BACKGROUND: Poor cardiovascular fitness (CVF) is a risk factor for obesity, as well as insulin resistance (IR), inflammation, and cardiovascular disease. We have previously shown that a school-based fitness curriculum can improve CVF, as well as IR and body composition in obese children. Whether such a program improves CVF, IR, and other health indicators in non-obese children is unresolved.

AIM: To determine whether a school-based fitness program improves body composition, CVF, markers of inflammation (e.g. CRP, TNF-alpha, adiponectin), and insulin sensitivity in nonobese children.

STUDY DESIGN: 35 non-obese middle school children with body mass index below the 95th percentile for age were enrolled in a 'fitness-oriented' gym class. Children underwent fasting evaluation of insulin, glucose, adiponectin, CRP, TNF-alpha, body composition by dual X-ray absorptiometry (DXA), and maximal VO2 treadmill testing at baseline (prior to the school year) and again at end of the school year.

MAIN OUTCOME MEASURES: Testing for CVF (maximal VO2 treadmill testing), DXA, and fasting evaluation of insulin, glucose, adiponectin, CRP and TNF-alpha.

RESULTS: Children demonstrated a decrease in BMI z-score (-0.14 +/- 0.33, p = 0.02), HOMA-IR (-0.15 +/- 0.35, p = 0.016), and TNF-alpha (-2.55 +/- 1.79 pg/ml, p < 0.001), and an increase in VO2(max) (+1.58 +/- 2.34 ml/kg/min, p < 0.001), adiponectin (+7,553 +/- 11,100 ng/ml, p < 0.001), and muscle mass (+2,282 +/- 1,882.73 g, p < 0.001) after nine months of study.

CONCLUSIONS: The school-based fitness oriented curriculum resulted in improved body composition and insulin sensitivity, increased CVF, and decreased inflammation in non-obese children. Combined with prior studies, these data demonstrate that school-based fitness curricula can benefit both obese and non-obese children. Partnerships with schools to promote fitness should be part of a public health approach to improving children's health.