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Biomedical subjects

Katie Watts

Publications and source records attributed to Katie Watts.

8 recordsLinked to original sources
PubMed2006

Do skinfolds accurately assess changes in body fat in obese children and adolescents?

PURPOSE: Obesity is epidemic in Western societies, with rapid rates of increase in the young. Various methods exist for the assessment of body composition, but these have not been compared in obese children and adolescents. This study compared methods of body composition assessment in obese young people to determine whether changes in various measures of body composition as a result of exercise training were correlated. METHODS: Multiple anthropometric measures (weight, height, body mass index (BMI), skinfolds, waist and hip girths) and dual-energy x-ray absorptiometry (DEXA) were undertaken in 38 obese children and adolescents (12.7 +/- 2.1 yr) at baseline and following 8 wk of exercise training. RESULTS: At baseline, there were strong relationships (all P < 0.01) between DEXA total fat and weight (r = 0.83), BMI (r = 0.86), waist girth (r = 0.81), hip girth (r = 0.88), sum of six skinfolds (sum6, r = 0.79), and percent body fat (percent body fat) calculated using a four-skinfold equation (EQ4; r = 0.69). Similar relationships (all P < 0.001) existed between DEXA abdominal fat and weight (r = 0.79), waist girth (r = 0.83), hip girth (r = 0.69), and height (r = 0.71). Neither skinfold sums, nor percent body fat calculated from skinfold equations, were selected as independent predictors of DEXA total or abdominal fat by stepwise hierarchical linear regression. The reductions in DEXA total and abdominal fat following exercise were not predicted by changes in skinfolds or percent body fat calculated from skinfolds. CONCLUSION: These data suggest that body fat derived from skinfold measures is poorly predictive of abdominal and total fat derived from DEXA in obese children and adolescents. This finding highlights the limitations of skinfolds in obese subjects and questions the validity of their use to assess changes in body composition with interventions such as exercise training.

Adolescent↗
PubMed2005

Exercise training in obese children and adolescents: current concepts.

Childhood obesity has reached epidemic proportions worldwide and is associated with increased cardiovascular mortality and morbidity in adult life. The increase in fat mass in children and adolescents has occurred concomitantly with a decline in reported time for exercise. Evidence suggests that non-physically active children are more likely to become non-physically active adults and that encouraging the development of physical activity habits in children helps establish patterns that continue into adulthood. Dietary treatment of obesity is relatively ineffective in adults and it has been suggested that prevention of obesity in childhood and adolescence should emphasise increased physical activity rather than diet because of fears relating to the adverse effects of inappropriate eating patterns. Despite this, there are very few randomised controlled studies investigating the efficacy of exercise training in obese children or adolescents and many of the extant studies have been poorly controlled and have not specifically stratified the independent effect of exercise versus dietary modification. This review focuses on the well designed controlled trials that have evaluated the effect of exercise training in obese children and adolescents on body composition, haemodynamic and metabolic variables, cardiovascular fitness, muscular strength and vascular function. These studies indicate that, although exercise training does not consistently decrease bodyweight or body mass index, it is associated with beneficial changes in fat and lean body mass, emphasising the importance of comprehensive assessment of body composition in future exercise-training studies. Exercise training improves cardiovascular fitness and muscular strength; however, it seems to have little effect on blood lipid profile or blood pressure in obese young people. Importantly, recent studies have demonstrated that exercise training improves vascular endothelial function, an important surrogate measure that may predict future atherosclerotic risk in obese children and adolescents. Given that improvement in vascular function in these training studies occurred in the absence of changes in lipid fractions, haemodynamic variables or glucose metabolism, exercise appears to have a direct beneficial effect on the vasculature, in addition to its putative benefits through risk-factor modification.

Adolescent↗
PubMed2004

Exercise training normalizes vascular dysfunction and improves central adiposity in obese adolescents.

OBJECTIVES: We sought to characterize the impact of obesity on vascular function in adolescents and to determine whether an exercise program reverses abnormalities in endothelial function. BACKGROUND: Obesity, a major modifiable risk factor for cardiovascular disease, is epidemic in Western societies, with rapid rates of increase in the young. Atherosclerosis begins in childhood, and endothelial dysfunction is its earliest detectable manifestation. METHODS: The influence of eight weeks of circuit training (CT) was examined in 19 obese subjects (14.3 +/- 1.5 years), using a randomized, crossover protocol. Functional capacity and muscular strength were assessed by standard techniques. Body composition was examined using anthropometric measures and dual-energy X-ray absorptiometry. Conduit vessel endothelial function was assessed using high-resolution ultrasound and flow-mediated dilation (FMD) of the brachial artery. RESULTS: Circuit training decreased abdominal and trunk fat and significantly improved fitness and muscular strength (p < 0.05). In the obese group, FMD was significantly impaired relative to control subjects (n = 20) at entry (5.3 +/- 0.9% vs. 8.9 +/- 1.5%, p < 0.05) and was normalized after CT (8.8 +/- 0.8%, p < 0.05). CONCLUSIONS: Circuit training improved functional capacity, muscular strength, and body composition in obese adolescents. Furthermore, conduit vessel function was normalized after exercise training. If vascular dysfunction is an integral component of the pathogenesis of vascular disease, this study supports the value of an exercise program in the management of obese adolescents.

Adipose Tissue↗
PubMed2004

Effects of exercise training on vascular function in obese children.

OBJECTIVES: Atherosclerosis is a disease that begins in childhood; endothelial dysfunction is its earliest detectable manifestation, and primary prevention strategies are likely to be most effective if instituted early. The aim of this study was to characterize the impact of obesity on vascular function in young children and to determine whether an exercise program improves abnormalities in vascular function. STUDY DESIGN: The influence of 8 weeks of exercise training was examined in 14 obese subjects, 8.9 +/- 0.4 years of age, with the use of a randomized crossover protocol. Conduit vessel endothelial function was assessed by means of high-resolution ultrasound and flow-mediated dilation of the brachial artery (FMD). RESULTS: Exercise training did not change subcutaneous fat mass, body weight, or body mass index. FMD in the obese group was significantly impaired relative to matched control subjects at entry (6.00% +/- 0.69% to 12.32% +/- 3.14%, P <.0001). FMD significantly improved with exercise training (7.35% +/- 0.99%, P <.05) in the obese group. CONCLUSIONS: Conduit vessel FMD, a validated surrogate measure of early atherosclerosis, was impaired in obese children but improved as a result of exercise training. This study supports the value of an exercise program in the treatment of obese children in a primary prevention setting.

Analysis of Variance↗
PubMed2004

Lack of effect of oral glucose loading on conduit vessel endothelial function in healthy subjects.

The aim of the present study was to investigate the impact of an oral glucose load on circulating insulin and glucose levels and arterial function in healthy non-diabetic subjects. Thirty-nine non-obese, healthy subjects (24 female, 15 male), aged 21.0+/-1.8 years of age, were randomly assigned to undergo either an OGTT (oral glucose tolerance test; 75 g of glucose) or administration of a placebo. Analyses of lipids, liver function and HbA(1c) (glycated haemoglobin) at baseline revealed results which were within the standard reference range. Insulin and glucose levels as well as vascular function [FMD (flow-mediated dilation)] were measured at 0, 60 and 120 min. Compared with baseline, the control subjects did not exhibit any significant changes in glucose or insulin levels, whereas, in the OGTT group, blood glucose levels at both 60 (5.4+/-1.7 mmol/l) and 120 (5.0+/-1.1 mmol/l) min increased significantly relative to baseline (4.1+/-0.4 mmol/l; both P<0.001) and, similarly, insulin levels were higher at both 60 (30.1+/-21.3 m-units/l) and 120 (34.9+/-23.6 m-units/l) min compared with baseline (4.7+/-4.3 m-units/l; both P<0.001). Although blood glucose and insulin levels changed, FMD did not significantly differ between time-points or between groups. In summary, despite significantly elevated glucose and insulin concentrations in these subjects, we observed no change in vascular function, suggesting that acute elevations of glucose and insulin within the clinically normal range are not associated with impaired vascular function in vivo.

Administration, Oral↗
PubMed2002

Increased gyrification in Williams syndrome: evidence using 3D MRI methods.

Understanding patterns of gyrification in neurogenetic disorders helps to uncover the neurodevelopmental etiology underlying behavioral phenotypes. This is particularly true in Williams syndrome (WS), a condition caused by de novo deletion of approximately 1 to 2 Mb in the 7q11.23 region. Individuals with WS characteristically possess an unusual dissociation between deficits in visual-spatial ability and relative preservations in language, music, and social drive. A preliminary postmortem study reported anomalous gyri and sulci in individuals with WS. The present study examined gyrification patterns in 17 participants with WS (10 females, 7 males; mean age 28 years 11 months, SD 8 years 6 months) and 17 age- and sex-matched typically developing control participants (mean age 29 years 1 month, SD 8 years 1 month) using new automated techniques in MRI. Significantly increased cortical gyrification was found globally with abnormalities being more marked in the right parietal (p=0.0227), right occipital (p=0.0249), and left frontal (p=0.0086) regions. These results suggest that one or more genes in the 7q11.23 region are involved during the critical period when cortical folding occurs, and may be related to the hypothesized dorsal/ventral dissociation in this condition.

Adult↗
PubMed2002

Effect of lower limb exercise on forearm vascular function: contribution of nitric oxide.

We examined vascular function in an inactive muscle bed, the forearm, during lower limb exercise and determined the contribution of endothelium-derived nitric oxide (NO) to the hyperemic response. Eight young males were randomized to participate in two studies, each consisting of two bouts of lower limb exercise, separated by a 30-min recovery. Peak forearm blood flow (PFBF) and mean blood flow (MFBF) were continuously recorded at baseline and during exercise using continuous high-resolution vascular ultrasound and Doppler flow velocity measurement. During one session, the brachial artery was cannulated to allow continuous infusion of saline or N(G)-monomethyl-L-arginine (L-NMMA), an inhibitor of NO synthase. The alternate session was performed to control for possible effects of repeated exercise. At 60, 100, and 160 W, L-NMMA significantly decreased both PFBF and MFBF compared with the saline infusion. These results suggest that systemic production of NO occurs during exercise in resting vessel beds, which do not feed metabolically active tissue. This finding provides a plausible explanation for the antiatherogenic benefits of exercise.

Adolescent↗