School-based Exercise Improves Fitness, Body Composition, Insulin Sensitivity, and Markers of Inflammation in Non-Obese Children

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