OBJECTIVE: To determine the effect of exercise training (ET) on components of the insulin resistance syndrome (IRS) in obese children. DESIGN: Randomized, modi®ed cross-over study, with subjects assigned to one of two conditions: (1) 4 months of ET followed by 4 months of no-ET; or (2) 4 months of no-ET followed by 4 months of ET. Measurements were made at three time points: 0, 4 and 8 months. SUBJECTS: 79 obese, but otherwise healthy children (age: 7 ± 11 y, percent fat (%fat) 27 ± 61%). MEASUREMENTS: Plasma lipid and lipoprotein concentrations, plasma insulin and glucose concentrations; %fat; submaximal heart rate (HR) as an index of ®tness. EXERCISE TRAINING: ET was offered 5 daweek 40 minad. For the 73 children who completed 4 months of ET, the mean attendance was 80% (that is, 4 daweek) and the average HR during ET was 157 bpm. RESULTS: Signi®cant (P`0.05) group x time interactions were found for plasma triglyceride (TG) and insulin concentrations and %fat. The average change for both groups, from just before ET to just after the 4 month ET was À0.24 mmol Á l À1 for TG, À25.4 pmol Á l À1 for insulin and À1.6 units for %fat. When Group 1 ceased ET, over the following 4 month period the average change for insulin was 26.6 pmol Á l À1 and for %fat 1.3 units. CONCLUSION: Some components (plasma TG, insulin, %fat) of the IRS are improved as a result of 4 months of ET in obese children. However, the bene®ts of ET are lost when obese children become less active.

GUTIN, BERNARD, S C O T T O W E N S , T O M O K IOKUYAMA, SHARON RIGGS, MICHAEL FERGUSON, AND MARK LITAKER. Effect of physical training and its cessation on percent fat and bone density of children with obesity. Obes Res. 1999;7:208-214. Objective: We determined the effect of 4-month periods of physical training (PT) and detraining on percent fat (percent fat) and bone density of children with obesity. Research Methods and Procedures:Subjects were 79 7-to 1 1-year-old children with obesity; 34 were white, 44 were black, and 1 was Asian, 26 were male and 53 were female.They were randomly assigned to two groups: group 1 engaged in PT for the first 4 months, while group 2 engaged in PT during the second 4 months. Body composition was measured with dual energy absorptiometry, and diet was measured with 4 days of recall for each 4-month period. PT was offered 5 dayslweek for 40 minuteslsession, heart rate monitors were worn, and no dietary information was given; mean attendance was 80%, and mean heart rate per session was 157 bpm. Results:Group by time interactions across the three timepoints (from analysis of variance) were significant for percent fat (p=

OWENS, SCOTT, BERNARD GUTIN, PAULE BARBEAU, MARK LITAKER, JERRY ALLISON, MATTHEW HUMPHRIES, TOMOKI OKUYAMA, AND NGOC-ANH LE. Visceral adipose tissue and markers of the insulin resistance syndrome in obese black and white teenagers. Obes Res. 2000;8:287-293. Objective: To determine the relationships between visceral and general adiposity, cardiovascular fitness, and markers of the insulin resistance syndrome in obese black and white teenagers. Research Methods and Procedures:Cross-sectional survey of 81 obese 13-to 16-year-old youths. Visceral adipose tissue was measured with magnetic resonance imaging, and percentage body fat was measured with dual-energy X-ray absorptiometry. Cardiovascular fitness was assessed with a submaximal treadmill test. Fasting blood samples were analyzed for lipids/lipoproteins and insulin. Resting blood pressure was obtained using an automated cuff. Results: Visceral adipose tissue was significantly correlated with unfavorable levels of: triacylglycerol (r ϭ 0.27, p Ͻ 0.05), total cholesterol (r ϭ 0.27, p Ͻ 0.05), high-density lipoprotein cholesterol (r ϭ Ϫ0.26, p Ͻ 0.05), the ratio of total cholesterol/high-density lipoprotein cholesterol (r ϭ 0.42, p Ͻ 0.01), low-density lipoprotein cholesterol (r ϭ 0.27, p Ͻ 0.05), apolipoprotein B (r ϭ 0.38, p Ͻ 0.01), and systolic blood pressure (r ϭ 0.30, p Ͻ 0.01). Multiple regression analyses revealed that visceral adipose tissue was more powerful than percentage body fat for explaining variance in lipoproteins (e.g., for the ratio of total cholesterol/high-density lipoprotein cholesterol, r 2 ϭ 0.13, p Ͻ 0.01, and for systolic blood pressure, r 2 ϭ 0.07, p Ͻ 0.05). Ethnicity was the most powerful of the demographic predictors for blood lipids (r 2 ϭ 0.15 for triacylglycerol with lower levels in blacks; r 2 ϭ 0.10 for high-density lipoprotein cholesterol with higher levels in blacks; r 2 ϭ 0.06 for the ratio of total cholesterol/high-density lipoprotein cholesterol with lower levels in blacks). Cardiovascular fitness was not retained as a significant predictor of markers of the insulin resistance syndrome. Discussion: Some of the deleterious relationships between visceral adiposity and markers for the insulin resistance syndrome seen in adults were already present in these obese young people.

Objective: The hypothesis studied was that variation in diet and physical activity would explain a significant portion of the interindividual variation in the response of body composition to physical training. Design: The participants were 71 obese children aged 7-11 y (22 boys, 49 girls; 31 whites, 40 blacks). Body composition was measured by dual-energy X-ray absorptiometry, physical activity by a 7-d recall interview, and diet by two, 2-d recalls. The children underwent 4 mo of physical training. Results: The mean attendance was 4 d/wk, the mean (± SD) heart rate for the 40-min sessions was 157 ± 7 beats/min, and the mean energy expenditure was 946 ± 201 kJ/session. On average, the percentage body fat decreased significantly in the total group, and total mass, fat-free soft tissue, bone mineral content, and bone mineral density increased, but there was a good deal of individual variability. Multiple regression models indicated that in general, more frequent attendance, being a boy, lower energy intake, and more vigorous activity were associated with healthier body-composition changes with physical training. Ethnicity was not retained as a correlate of the change of any component of body composition. Conclusions: In obese children, age, vigorous activity, diet, and baseline percentage body fat together accounted for 25% of the variance in the change in percentage body fat with physical training.Am J Clin Nutr 1999;69:705-11.

Objective: To compare physical characteristics, health and fitness-related variables, and nutrient intake between children of Japanese ancestry living in the United States and Japan.Design: Cross-sectional study.Setting: Miami, Fla, and Tsukuba, Japan.Subjects: Fourteen children of Japanese descent living in the United States and 14 sex-and age-matched children living in Japan.Main Outcome Measures: US and Japanese resident groups were compared on physical characteristics, health and fitness-related variables, and nutrient intake using the t test for paired samples. To assess differences between groups in variables not statistically significant, effect sizes were calculated using the Cohen d test of standardized differences. Results:The following significant differences were found between US and Japanese resident groups, respectively: body mass index, 19. Conclusions: A small sample (n=14) of children of Japanese descent living in Florida showed more adverse healthrelated characteristics than did a comparable group of their peers living in Japan. The results are probably related to differences in their diets. It remains to be seen whether the differences in diets are related to where the children live.