Both 60 min of moderate and vigorous intermittent exercises reduced postprandial [TAG]. However, the extra energy expended in the vigorous condition did not produce a dose-related reduction compared with the moderate-intensity condition.

PURPOSE: The effect of exercise intensity and sex on postprandial risk factors for cardiovascular disease in adolescents is unknown. We examined the effect of a single bout of work-matched high-intensity interval exercise (HIIE) and moderate intensity exercise (MIE) on postprandial triacylglycerol (TAG) and systolic blood pressure (SBP) in adolescents.METHOD: Twenty adolescents (10 male, 14.3 ± 0.3 y) completed three 1-day trials: 1) rest (CON); 2) 8 x 1 min cycling at 90% peak power with 75 s recovery (HIIE); 3) cycling at 90% of the gas exchange threshold (MIE), one hour before consuming a high fat milkshake (1.50 g fat and 80 kJ•kg -1 ). Postprandial TAG, SBP and fat oxidation were assessed over four hours.RESULTS: Compared to CON, the incremental area under the curve for TAG (IAUC-TAG)was not significantly lowered in HIIE (P=0.

Both continuous-exercise and intermittent-games activity reduce [TAG] in healthy adolescent boys when performed the afternoon before ingesting a high-fat meal.

This study examined the effects of 30 and 60 min of moderate intensity exercise on postprandial triacylglycerol concentration [TAG] in 11 healthy, 13-year-old boys. The boys completed three counterbalanced conditions. On day 1, they either rested (CON), or jogged for 30 min (EX30) or 60 min (EX60) at 55% peak [Formula: see text] Following a 12-h fast, on day 2 a capillary blood sample was taken for fasting [TAG] before a high fat milkshake was consumed. Further blood samples were taken every hour over a 6-h postprandial rest period for [TAG]. The estimated energy expenditure for EX30 (982 kJ) was doubled in EX60 (1967 kJ). Differences in fasting [TAG] between the conditions were small (ES = 0.23, P = 0.35). Differences in postprandial TAG over time between conditions were identified (ES = 0.41, P = 0.03). Mean [TAG] was lower in EX60 than CON (-33 to -3%, P = 0.03) with a similar strong trend for EX30 (-29 to 1%, P = 0.06); EX60 and EX30 were not different from each other (-21 to 14%, P = 0.62). The total area under the [TAG] versus time curve was different between conditions (ES = 0.42, P = 0.03). Again, EX60 was lower than CON (-31 to -2%, P = 0.02) with a strong trend for EX30 (-31 to 4%, P = 0.06); EX30 and EX60 were not different from each other (-17 to 16%, P = 0.58). This study shows for the first time that both 30 and 60 min of jogging, with energy expenditures equivalent to 982 and 1,967 kJ, attenuates postprandial [TAG] in adolescent boys, but not in a dose-dependent manner.

Although a large body of evidence exists documenting the ergogenic properties of caffeine, most studies have focused on endurance performance. However, findings from endurance sports cannot be generalized to performance in ball games where, apart from having a high level of endurance, successful athletic performances require a combination of physiological, technical and cognitive capabilities. The purpose of this review was to critically evaluate studies that have examined the effect of a single dose of caffeine in isolation on one or more of the following performance measures: total distance, sprint performance, agility, vertical jump performance and accuracy in ball games. Searches of three major databases resulted in 19 studies (invasion games: 13; net-barrier games: 6) that evaluated the acute effects of caffeine on human participants, provided the caffeine dose administered, and included a ball games specific task or simulated match. Improvements in sprint performance were observed in 8 of 10 studies (80%), and vertical jump in 7 of 8 studies (88%). Equivocal results were reported for distance covered, agility and accuracy. Minor side effects were reported in 4 of 19 studies reviewed. Pre-exercise caffeine ingestion between 3.0 and 6.0 mg/kg of body mass appears to be a safe ergogenic aid for athletes in ball games. However, the efficacy of caffeine varies depending on various factors, including, but not limited to, the nature of the game, physical status and caffeine habituation. More research is warranted to clarify the effects of caffeine on performance measures unique to ball games, such as agility and accuracy. It is essential that athletes, coaches and practitioners evaluate the risk-benefit ratio of caffeine ingestion strategies on an individual case-by-case basis.

The ingestion of high-fat meals induces a state of endothelial dysfunction in adults. This dysfunction is attenuated by prior exercise. The response of young people to these nutritional and physiological stressors has not been established. Thus, the purpose of the present study was to investigate if a bout of moderate-intensity exercise influenced endothelial function (as indicated by flow-mediated dilation (FMD)) following the ingestion of a high-fat breakfast and lunch in adolescent boys (aged 12·6-14·3 years). Two, 2 d main trials (control and exercise) were completed by thirteen adolescent boys in a counter-balanced, cross-over design. Participants were inactive on day 1 of the control trial, but completed 60 min of walking at 60 % peak oxygen uptake in the exercise trial. On day 2, endothelial function was assessed via FMD prior to, and following, ingestion of a high-fat breakfast and lunch. There was no difference in fasting FMD between the control and exercise trial (P¼ 0·449). In the control trial, FMD was reduced by 32 % following consumption of the high-fat breakfast and by 24 % following lunch. In the exercise trial, the corresponding reductions were 6 and 10 %, respectively (main effect trial, P¼ 0·002). These results demonstrate that moderate-intensity exercise can attenuate the decline in FMD seen following the consumption of high-fat meals in adolescent boys.

This study investigated if repeated, very short duration sprints influenced endothelial function (indicated by flow-mediated dilation) and triacylglycerol concentrations following the ingestion of high-fat meals in adolescent boys. Nine adolescent boys completed two, 2-day main trials (control and exercise), in a counter-balanced, crossover design. Participants were inactive on day 1 of the control trial but completed 40 x 6 s maximal cycle sprints on day 1 of the exercise trial. On day 2 capillary blood samples were collected and flow-mediated dilation measured prior to, and following, ingestion of a high-fat breakfast and lunch. Fasting flow-mediated dilation and plasma triacylglycerol concentration were similar in the control and exercise trial (P>0.05). In the control trial flow-mediated dilation was reduced by 20% and 27% following the high-fat breakfast and lunch; following exercise these reductions were negated (main effect trial, P<0.05; interaction effect trial x time, P<0.05). The total area under the plasma triacylglycerol concentration versus time curve was 13% lower on day 2 in the exercise trial, compared to the control trial (8.65 (0.97)

This is the first study to show that low-volume HIIR attenuates postprandial TAG concentration in healthy, active 11- to 12-yr-old boys.