Exercise training normalises vascular function and improves body composition in obese adolescents K. Watts ~*, A. Siafarikas 3., E. Davis 3, T. Jones ~, G. O'Driscoll 2 & D. Green ~

'School of Human Movement and Exercise Science, The University Of Western Australia ~Cardiac Transplant Unit, Royal Perth Hospital

3Department of Endocrinology & Diabetes, Princess Margaret Hospital

Obesity is epidemic in western societies but treatment of established obesity in adults is relatively ineffective and primary prevention should be emphasised, particularly as obesity and inactivity in adolescents are increasing. Atherosclerosis begins in childhood and vascular endothelial dysfunction its earliest detectable manifestation. Few studies have examined the effect of exercise training in obese adolescents and none have specifically determined its effect on vascular function. The influence of 8 weeks of supervised circuit training was examined in 19 obese subjects (14.3 _+ 0.3 yrs), using a randomised crossover protocol. Functional capacity and muscular strength were assessed by standard techniques. Body composition was examined using anthropometry (6 skinfolds, hip:waist) and DEXA. Endothelial function was assessed using high-resolution ultrasound and flow-mediated dilation of the brachial artery. Training decreased fat mass (DEXA) in the abdominal and trunk regions (p<0.05); skinfolds did not change. Cardiovascular fitness and muscular strength significantly improved (p<0.05). Vascular function in the obese group was significantly impaired relative to matched controls (n = 20) at entry (5.3 + 0.9% vs 8.9 + 1.5%, p<0.05) and normalised as a result of CT (8.8 + 0.8%, p<0.05). This is the first study to demonstrate that vascular function, a validated precursor and surrogate measure of early atherosclerosis, is impaired in obese adolescents and normalised by exercise training. Training also decreased visceral adiposity, an independent risk factor for future type 2 diabetes. This study supports the value of an exercise program in the management of obese adolescents forprimary prevention of future cardiovascular disease.

Sex, age and plantar pressure: How are they affected by obesity? A. Dowling'*, J. Steele 1 & L. Baur ~

'Department of Biomedical Science, University of Wollongong 2Department of Paediatrics and Child Health, The Children's Hospital at Westmead

Obese children have been shown to generate higher plantar pressures when walking, compared to their non-obese counterparts, possibly contributing to an increased risk of developing foot pathologies. However, no research has previously investigated how sex and age may moderate the effects of obesity on these variables. Therefore, the purpose of this study was to determine the effects of sex and age on the plantar pressures generated by obese children when walking. Barefoot plantar pressures generated by 15 obese boys and 30 obese girls (mean age = 9.2 + 1.4 y) were monitored as they walked across a Novel pressure platform (2-step method; 5 trials/limb; 25 Hz). Average plantar pressure data for one randomly selected limb per subject were then analysed using Novel software. Two-way ANOVA indicated a significant (p <0.05) main effect of age on most of the plantar pressure variables whereby older children (10-12 y) exerted greater peak forces across most regions of their feet compared to younger (7-9 y) children. These forces were generated over a larger area, in most foot regions; although the increase in area was insufficient to account for the increased forces such that the older children experienced higher plantar pressures, particularly in the forefoot and toes. Limited main effects for gender were noted, although gender effects may have been masked by the uneven distribution of obese boys and girls. It was concluded that researchers and practitioners must factor in age and, to a lesser extent, sex when investigating or treating plantar pressure variables in obese children.

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