This study assessed the effectiveness of a six-week, high-intensity, games-based intervention on physiological and anthropometric indices of health, in normal weight (n=26; 32.5±8.9 kg) and obese (n=29; 49.3±8.9 kg) children (n= 32 boys, 23 girls), aged 8-10 years. Children were randomised into an exercise or control group. The exercise group participated in a twice-weekly, 40 minute active games intervention, alongside their usual school physical education classes. The control group did not take part in the intervention. Before and after the intervention, participants completed both a maximaland submaximal graded exercise test. The submaximal exercise test comprised of a six minute, moderate-and six minute heavy intensity bout, interspersed with a five minute recovery. The exercise group demonstrated improvements in maximal oxygen uptake (51.4±8.5 vs 54.3±9.6 ml·kg -1 ·min -1 ) and peak running speed (11.3±1.6 vs 11.9±1.6 km·h -1 ), and a reduction in the oxygen cost of submaximal exercise between assessments (P<.05). A decrease in waist circumference and increase in muscle mass were observed between assessments for the obese participants randomised to the intervention (both P<.05). This study demonstrates that a short-term, high-intensity games intervention, may elicit positive changes in physiological and anthropometric indices of health, in normal weight and obese children.

The pulmonary oxygen uptake response is deleteriously influenced by obesity in prepubertal children, as evidenced by a slower phase II response. To date, no studies have investigated the ability of an exercise intervention to ameliorate this. The objective of the study was to investigate the influence of a 6-week, high-intensity, games-orientated intervention on the oxygen uptake kinetic response of prepubertal obese and normal-weight children during heavy-intensity exercise. Thirteen normal-weight and 15 obese children participated in a twice-weekly exercise intervention involving repeated bouts of 6-min high-intensity, games-orientated exercises followed by 2 min of recovery. Sixteen normal-weight and 11 obese children served as a control group. At baseline and post-intervention, each participant completed a graded-exercise test to volitional exhaustion and constant work-rate, heavy-intensity exercise. Post-intervention, obese children demonstrated a reduced phase II τ (pre-intervention: 30 ± 8 cf. post-intervention: 24 ± 7 s), mean response time (pre-intervention: 50 ± 10 cf. post-intervention: 38 ± 9 s) and phase II amplitude (pre-intervention: 1.51 ± 0.30 cf. post-intervention: 1.34 ± 0.27 L·min(-1)). No changes were evident in the normal-weight children. In conclusion, the present findings demonstrate that a 6-week, high-intensity intervention can have a significant positive impact on the dynamic oxygen uptake response of obese prepubertal children.

To assess the influence of obesity on the oxygen uptake VO2 kinetics of pre-pubertal children during moderate- and heavy intensity treadmill exercise. We hypothesised that obese (OB) children would demonstrate significantly slower VO2 kinetics than their normal weight (NW) counterparts during moderate- and heavy intensity exercise. 18 OB (9.8 ± 0.5 years; 24.1 ± 2.0 kg m(2)) and 19 NW (9.7 ± 0.5 years; 17.6 ± 1.0 kg m(2)) children completed a graded-exercise test to volitional exhaustion and two submaximal constant work rate treadmill tests at moderate (90 % gas exchange threshold) and heavy (∆ 40 %) exercise intensities. Bodyweight significantly influenced the VO2 kinetics during both moderate- and heavy exercise intensities (P < 0.05). During moderate intensity exercise, the phase II τ (OB: 30 ± 13 cf. NW: 22 ± 7 s), mean response time (MRT; OB: 35 ± 16 cf. NW: 25 ± 10 s), phase II gain (OB: 156 ± 21 cf. NW: 111 ± 18 mL O2 kg(-1) km(-1)) and oxygen deficit (OB: 0.36 ± 0.11 cf. NW: 0.20 ± 0.06 L) were significantly higher in the OB children (all P < 0.05). During heavy intensity exercise, the τ (OB: 33 ± 9 cf. NW: 27 ± 6 s; P < 0.05) and phase II gain (OB: 212 ± 61 cf. NW: 163 ± 23 mL O2 kg(-1) km(-1); P < 0.05) were similarly higher in the OB children. A slow component was observed in all participants during heavy intensity exercise, but was not influenced by weight status. In conclusion, this study demonstrates that weight status significantly influences the dynamic VO2 response at the onset of treadmill exercise in children and highlights that the deleterious effects of being obese are already manifest pre-puberty.

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