ABSTRACT. Background. Low levels of energy expenditure and aerobic fitness have been hypothesized to be risk factors for obesity. Longitudinal studies to determine whether energy expenditure influences weight gain in whites have provided conflicting results. To date, no studies have examined this relationship in blacks or whether aerobic fitness influences weight gain in white or black children.Methods. One hundred fifteen children, 72 white (55 girls and 17 boys) and 43 black (24 girls and 19 boys) were recruited for this study. Aerobic fitness, resting, total, and activity-related energy expenditure and body composition were measured at baseline. The children returned annually for 3 to 5 repeated measures of body composition. The influence of the initial measures of energy expenditure and fitness on the subsequent rate of increase in adiposity was examined, adjusting for initial body composition, age, ethnicity, gender, and Tanner stage. Because 20 children did not attain maximum oxygen consumption, the sample size for the combined analysis was 95.Results. Initial fat mass was the main predictor of increasing adiposity in this cohort of children, with greater initial fat predicting a higher rate of increase of adiposity. There was also a significant negative relationship between aerobic fitness and the rate of increasing adiposity (F 1,82 ‫؍‬ 3.92). With every increase of .1 L/minute of fitness, there was a decrease of .081 kg fat per kg of lean mass gained. None of the measures of energy expenditure significantly predicted increasing adiposity in white or black children.Conclusions. Initial fat mass was the dominant factor influencing increasing adiposity; however, aerobic fitness was also a significant independent predictor of increasing adiposity in this cohort of children. Resting, total, or activity-related energy expenditure did not predict increasing adiposity. It seems that aerobic fitness may be more important than absolute energy expenditure in the development of obesity in white or black children. Pediatrics 2000;106(4). URL: http://www. pediatrics.org/cgi/content/full/106/4/e50; energy expenditure, fitness, longitudinal, obesity.

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This study examined changes in postprandial lipemia in endurance-trained people during a short interruption to training. Nine men and one woman (ages 18-55 yr) undertook fat tolerance tests after 15 h, 60 h, and 6.5 days without exercise. The test meal (1.2 g fat, 1.1 g carbohydrate, 66 kJ/kg body mass) was consumed after a 12-h fast. Postprandial lipemia increased rapidly with detraining (area under plasma triacylglycerol vs. time curve: 8.42 +/- 1.40, 11. 35 +/- 1.38, and 11.97 mM x 6 h at 15 h, 60 h and 6.5 days, respectively). In the fasted state, plasma triacylglycerol concentration (0.85 +/- 0.15, 1.09 +/- 0.12, and 1.10 +/- 0.11 mM at 15 h, 60 h and 6.5 days, respectively) and the ratio of total cholesterol to high-density-lipoprotein cholesterol increased with detraining. Values were significantly higher at 60 h and 6.5 days than values at 15 h ( P < 0.05) for each of these three variables. The serum insulin response was higher ( P < 0.05) at 6.5 days than at 15 h (81.6 +/- 11.3, 87.6 +/- 11.4, and 94.5 +/- 9.4 microIU/ml x 6 h at 15 h, 60 h, and 6.5 days, respectively). Frequent exercise is needed to maintain a low level of postprandial lipemia and insulinemia in trained people.

Monitoring dietary intake patterns among children is important in order to explore and prevent the onset of adult health problems. The aim of the present study was to compare children's dietary intakes with national recommendations and to determine whether sex or ethnic differences were evident. This was done using a methodology that allows assessment of intake from the major components of the Food Guide Pyramid developed by the United States Department of Agriculture (USDA: ). The sample studied included 110 African-American and Caucasian males and females (mean age 9·9 years, BMI 20·1 kg/m2) from Birmingham, AL, USA, who were participating in a study investigating the development of obesity. Dietary data were based on three 24 h recalls and food group intake was determined using the USDA Pyramid Servicing Database. The results indicated that a high percentage of subjects failed to meet the recommended number of servings from each of the food groups. For example, only 5 % and 9 % met fruit and dietary group recommendations respectively. Consumption of foods from the Pyramid ‘tip’ (including discretionary fat and added sugar) contributed almost 50 % of the diet. African-Americans were more likely to meet requirements for the meat group, with a higher proportion of Caucasians meeting dietary recommendations. Males were more likely to meet the vegetable group guidelines although females consumed more energy per day from discretionary fat. In conclusion, these results suggest that implementation of nutrition education programmes may be important for promoting healthy nutrition among American children.

In this study, we examined the effects of 1 and 2 h of brisk walking on post-prandial metabolism. Eleven pre-menopausal women participated in three oral fat tolerance tests with different pre-conditions: control (no exercise), 1 h walk (1 h of walking at 50% maximal oxygen uptake, VO2max, on the day before) and 2 h walk (2 h walking at 50% VO2max on the day before). Venous blood samples were taken in the fasted state and for 6 h after ingestion of a high-fat mixed meal. Compared with the control trial, the 1 h walk reduced post-prandial lipaemia by a mean of 9.3%, whereas the 2 h walk reduced it by 22.8% (P < 0.01 for trend). Similarly, the 2 h walk reduced the post-prandial insulin response to a greater extent than the 1 h walk (17.3 vs 7.6%; P < 0.05 for trend). The results demonstrate that the beneficial effects of exercise on post-prandial metabolism are related to the duration and, therefore, the energy expenditure of the exercise session.

The present study examined the influence of training, followed by a short period of detraining, on postprandial lipaemia. Fourteen normolipidaemic, recreationally active young adults aged 18-31 years participated, in two self-selected groups: three men and five women (BMI 21 . 7-27 . 6 kg/ m 2 ) completed 13 weeks of running training, after which they refrained from exercise for 9 d; three men and three women (BMI 21 . 5-25 . 6 kg/m 2 ) maintained their usual lifestyle. Oral fat tolerance tests were conducted at baseline and again 15 h, 60 h and 9 d after the runners' last training session. Blood samples were drawn after an overnight fast and at intervals for 6 h after consumption of a high-fat meal (1 . 2 g fat, 1 . 4 g carbohydrate, 70 . 6 kJ energy/kg body mass). Heparin was then administered (100 IU/kg) and a further blood sample was drawn for measurement of plasma lipoprotein lipase (EC 3.1.1.34; LPL) activity. Endurance fitness improved in runners, relative to controls (maximal O 2 uptake þ3 : 2 (SE 1 . 1) ml/kg per min v. ¹1 : 3 (SE 1 . 2) ml/ kg per min; P < 0 : 05). In the absence of the acute effect of exercise, i.e. 60 h after the last training session, there was no effect of training on either postprandial lipaemia or on post-heparin LPL activity. However, changes during 9 d of detraining in both these variables differed significantly between groups; after 2 d without exercise (60 h test), the runners' lipaemic response was 37 % higher than it was the morning after their last training session (15 h test; runners v. controls P Ͻ 0 . 05), with a reciprocal decrease in post-heparin LPL activity (P < 0 : 01). These findings suggest that improved fitness does not necessarily confer an effect on postprandial lipaemia above that attributable to a single session of exercise. Exercise: Postprandial metabolism: Triacylglycerols

This study compared the postprandial triacylglycerol (TAG) response to a high-fat meal in trained and untrained normolipidemic young adults after 2 days' abstinence from exercise. Fifty-three subjects (11 endurance-trained men, 9 endurance-trained women, 10 sprint/strength-trained men, 11 untrained men, 11 untrained women) consumed a meal (1.2 g fat, 1.1 g carbohydrate, 66 kJ per kg body mass) after a 12-h fast. Venous blood samples were obtained in the fasted state and at intervals until 6 h. Postprandial responses were the areas under the plasma or serum concentration-vs.-time curves. Neither fasting TAG concentrations nor the postprandial TAG response differed between trained and untrained subjects. The insulinemic response was 29% lower in endurance-trained men than in untrained men [mean difference -37.4 (95% confidence interval -62.9 to -22.9) microIU/ml x h, P = 0.01]. Responses of plasma glucose, serum insulin, and plasma nonesterified fatty acids were all lower for endurance-trained men than for untrained men. These findings suggest that, in young adults, no effect of training on postprandial lipemia can be detected after 60 h without exercise. The effect on postprandial insulinemia may persist for longer.

This study aimed to determine whether changes in plasma heparin-releasable lipoprotein lipase (LPL) activity following a brisk walk were associated with decreases in fasting and/or postprandial triglyceride (TG) concentrations. Two groups of pre-menopausal women participated. In one group (fasting study group, n=10), TG concentrations and post-heparin plasma LPL activity were measured in the fasted state on two occasions: approximately 18 h after a 2-h treadmill walk at 50% maximal oxygen uptake (exercise trial); and after a day of no exercise (control trial). The other group (postprandial study group, n=9) undertook two oral fat tolerance tests (blood samples taken fasting and for 6 h after a high-fat meal), with plasma LPL activity measured 6 h after meal ingestion. Pre-conditions were the same as for the fasting study group (i.e. control and prior exercise). Prior exercise reduced fasting TG concentrations by 23 (7)% (fasting study group) [mean (SEM)] and by 18 (9)% (postprandial study group) (both P<0.05), and the postprandial TG response by 23 (6)% (postprandial study group) (P<0.01). Plasma LPL activity was not significantly increased by exercise in either the fasting or postprandial study groups. However, exercise-induced changes in both fasting and postprandial LPL activity were significantly correlated with the respective exercise-induced changes in fasting TG concentration and the postprandial TG response (r=-0.70 and -0.77 respectively, P<0.05 for both). These data suggest that increased LPL activity may contribute to the hypotriglyceridaemic effect of moderate exercise, although other mechanisms are also likely to be involved.