Effects of acute exercise on postprandial triglyceride response after a high-fat meal in overweight black and white adolescents.

OBJECTIVE: We examined the effects of acute exercise on postprandial triglyceride (TG) metabolism following a high-fat meal in overweight black vs white adolescents. DESIGN AND SUBJECTS: Twenty-one black and 17 white adolescents (12-18 yrs, body mass index 85th percentile) were evaluated twice, during control versus exercise trials, 1-4 weeks apart, in a counterbalanced randomized design. In the control trial, participants performed no exercise on day 1. In the exercise trial, participants performed a single bout of 60-min exercise (50% VO2 peak) on a cycle ergometer on day 1. On day 2 of both trials, participants consumed a high-fat breakfast (70% calories from fat) and blood was sampled for TG concentration in the fasted state and for 6 h postprandially. RESULTS: There was a significant main effect of condition on postprandial peak TG concentration (P=0.01) and TG area under the curve (AUC) (P=0.003), suggesting that independent of race, peak TG and TG-AUC was lower in the exercise trial vs control trial. Including Tanner stage, gender, total fat (kg) and visceral adipose tissue (VAT) as independent variables, stepwise multiple regression analyses revealed that in whites, VAT was the strongest (P<0.05) predictor of postprandial TG-AUC, explaining 56 and 25% of the variances in TG-AUC in the control and exercise trials, respectively. In blacks, VAT was not associated with postprandial TG-AUC, independent of trial. CONCLUSION: A single bout of aerobic exercise preceding a high-fat meal is beneficial to reduce postprandial TG concentrations in overweight white adolescents to a greater extent than black adolescents, particularly those with increased visceral adiposity.

Exercise-induced suppression of acylated ghrelin in humans.

Ghrelin is an orexigenic hormone secreted from endocrine cells in the stomach and other tissues. Acylation of ghrelin is essential for appetite regulation. Vigorous exercise induces appetite suppression, but this does not appear to be related to suppressed concentrations of total ghrelin. This study examined the effect of exercise and feeding on plasma acylated ghrelin and appetite. Nine male subjects aged 19-25 yr participated in two, 9-h trials (exercise and control) in a random crossover design. Trials began at 0800 in the morning after an overnight fast. In the exercise trial, subjects ran for 60 min at 72% of maximum oxygen uptake between 0800 and 0900. After this, they rested for 8 h and consumed a test meal at 1100. In the control trial, subjects rested for 9 h and consumed a test meal at 1100. Area under the curve values for plasma acylated ghrelin concentration (assessed from venous blood samples) were lower over the first 3 h and the full 9 h of the exercise trial compared with the control trial: 317+/-135 vs. 510+/-186 pg.ml(-1).3 h and 917+/-342 vs. 1,401+/-521 pg.ml(-1).9 h (means+/-SE) respectively (P<0.05). Area under the curve values for hunger (assessed using a visual scale) were lower over the first 3 h of the exercise trial compared with the control trial (P=0.013). These findings demonstrate that plasma acylated ghrelin concentration and hunger are suppressed during running.

Evaluation of soil radioactivities using pedologically based sampling techniques.

A new type of soil sampling protocol is suggested which has applicability to surveys of environmental radioactivity. Often there is a higher concentration of radionuclides in the lower B horizon than in the upper A horizon of well-drained, well-developed soils. It is recommended that soils be sampled pedologically, i.e., by soil horizon, rather than incrementally in depth. An example is given from a site in northern Louisiana where surface and/or the classical 15 cm ("six-inch") deep sampling could lead to erroneous conclusions regarding anthropogenic contamination.