In a multinational sample of children, more frequent breakfast consumption was associated with lower BMI z-scores and BF% compared with occasional and rare consumption. Associations were not consistent across all 12 countries. Further research is required to understand global differences in the observed associations.

A bout of Fatmax exercise performed ~16 h before high-glycemic-index breakfast consumption reduced fasting and postprandial insulin concentrations in NO girls and increased fat oxidation in both OW and NO girls. The higher postintervention energy and CHO intake in the OW compared with the NO girls or differences in metabolism between the two groups may have compromised potential exercise-induced reductions in insulin the OW girls.

Previous studies have linked short sleep duration, poor sleep quality, and late sleep timing with lower health-related quality of life (HRQoL) in children. However, almost all studies relied solely on selfreported sleep information and most were conducted in high income countries. To address these gaps, we studied both device-measured and self-reported sleep characteristics in relation to HRQoL in a sample of children from 12 countries that vary widely in terms of economic and human development. MethodsThe study sample included 6,626 children aged 9-11 years from Australia,

Consensus on the exercise protocol used to measure Fatmax (exercise intensity corresponding to maximum fat oxidation (MFO)) in children has not been reached. The present study compared Fatmax estimated using the 3 min incremental cycling protocol (3-INC) and a protocol consisting of several 10 min constant work rate exercise bouts (10-CWR) in 26 prepubertal children. Group Fatmax values were the same for 3-INC and 10-CWR (55% VO2peak) and 95% limits of agreement (LoA) were ± 7% VO2peak. Group MFO values were similar between protocols, although 95% LoA were -94 to 113 mg·min-1. While 3-INC provides a valid estimation of Fatmax compared with 10-CWR, caution should be exercised when estimating MFO in prepubertal children.

Substrate metabolism differs between children and adults and is important for weight management during childhood. A direct comparison of fat oxidation over a range of exercise intensities and the estimation of Fatmax (exercise intensity that elicits maximal fat oxidation (MFO)) during treadmill (TM) and cycling exercise (CE) does not appear to be available in children. Fat oxidation and Fatmax were compared during TM and CE in 22 pre- to early pubertal children (9 girls and 13 boys). Fat oxidation was higher for TM compared with CE over a range of absolute and relative exercise intensities and this difference was more pronounced at higher intensities (P ≤ 0.05). Fat oxidation was higher in boys compared with girls at similar relative, but not absolute intensities (P ≤ 0.05). Fatmax was higher during TM compared with CE and higher in boys compared with girls (P ≤ 0.05). The 5% Fatmax zone (range of exercise intensities where fat oxidation was within 5% of MFO) spanned a wider range of intensities for TM compared with CE (P ≤ 0.05). Collectively, these findings suggest that exercise programmes aimed at promoting high rates of fat oxidation in pre- to early pubertal children should include TM rather than CE regardless of exercise intensity. Furthermore, Fatmax values indicate that brisk walking or slow running promotes MFO rates in this population.

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Background/Objectives: The metabolic responses to mixed breakfast meals with different glycemic indexes (GI) and their effects on substrate metabolism during exercise in adolescent girls have not been examined. The interaction with weight status also warrants investigation. This study investigated the effect of mixed breakfast meals containing high GI (HGI) or low GI (LGI) carbohydrates on metabolic responses and fat oxidation during rest and exercise in overweight (OW) and non-overweight (NO) adolescent girls. Subjects/Methods: A total of 8 OW and 12 NO adolescent girls consumed an isoenergetic HGI (GI ¼ 73) or LGI (GI ¼ 44) breakfast 120 min before completing a 30-min treadmill walk at 50% V O 2peak . Results: Peak blood glucose concentration was higher for HGI compared with LGI in OW (P ¼ 0.023), but not NO (P40.05) girls. Blood glucose total area under the curve (TAUC) was 13% higher in HGI compared with LGI in OW (P ¼ 0.006), but only 4% higher in NO (P ¼ 0.072) girls. Plasma insulin data were log e transformed (lninsulin). Plasma lninsulin concentrations were not different between HGI and LGI (P40.05). Peak plasma lninsulin concentration (P ¼ 0.016) and TAUC (P ¼ 0.001) were greater in OW than NO girls. Fat oxidation during postprandial rest and exercise was not different between breakfasts (P40.05). Conclusions:The elevated glycemic response in HGI compared with LGI was more pronounced in OW girls, suggesting a reduced ability to cope with the metabolic demands of the HGI, but not LGI, breakfast. Manipulation of breakfast GI did not alter fat oxidation during rest or subsequent moderate intensity exercise in OW and NO adolescent girls.

These findings demonstrate impairment in the factors determining V'O(2) kinetics in OW children at a relatively young age. Furthermore, assessment of cardiorespiratory fitness using peak exercise values is likely to be misleading and not useful when designing exercise programmes for OW children.