EFFECTS OF DIETARY MACRONUTRIENT INTAKE AND RESISTANCE TRAINING EXERCISE ON G

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 摘要 在过去的30年里，美国超重儿童(6-19岁)的患病率(BMV&GT；95百分位数)增加了3倍，2000年达到16%(NHANES)。伴随着儿童超重的增加，儿童(0-19岁)2型糖尿病的发病率增加了4倍。虽然肥胖相关的糖代谢障碍的病因是多因素的，但饮食中大量营养素的摄入和体力活动是潜在的重要因素。这项建议的目的是在健康的青少年中确定1)肥胖对能量消耗和底物氧化、糖异生和糖原分解产生的葡萄糖、胰岛素的分泌和敏感性以及脂肪分解的影响；2)12周的抗阻训练计划是否会改善肥胖青少年的葡萄糖代谢，如果是，3)运动效果是否与总心肌细胞内、内脏和/或肝脏脂肪含量的减少有关。为了解决这些问题，将对12名超重(体脂30%)和12名瘦(体脂25%)青少年进行两次研究(就在12周锻炼计划开始之前和最后一周锻炼结束时)；在所有受试者中，每一次研究之前都将进行7-d的高脂肪饮食。将使用最先进的稳定同位素-GCMS技术和磁共振成像来获得实现上述目标所需的数据。这些研究提供的信息将提高我们对肥胖对青少年代谢影响的理解，将导致识别可能增加、预防或延缓2型糖尿病发展的因素。它还将帮助我们确定，不打算减肥的力量运动是否会改善超重青少年的胰岛素敏感性并使葡萄糖代谢正常化。 假设 总体假设：阻力训练(没有减肥目的)改善了健康肥胖青少年的胰岛素敏感性，使葡萄糖代谢正常化，并减少了细胞内、内脏和肝脏内的脂肪。 具体假设：H1。12周的抗阻锻炼计划(每周2次，每次1小时)增加了肥胖青少年的胰岛素敏感性，但对已经对胰岛素敏感的瘦青少年没有。 H2。运动诱导的胰岛素活性变化与运动诱导的心肌细胞内脂肪含量的变化呈负相关。 H3.为期12周的抵抗力运动计划将通过减少肝脏脂肪堆积来使肥胖青少年的糖异生正常化。 具体目标 目的：探讨12周耐力训练(2次/周，1小时/次)是否能提高肥胖青少年的胰岛素敏感性，减少糖异生，降低细胞内脂肪和肝脏脂肪含量。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. ABSTRACT Over the past 30 y the prevalence of overweight children (6-19 y) in the USA (BMV>95th percentile) has increased 3-fold to reach 16% in 2000 (NHANES). Concomitant with the increase in childhood overweight, the incidence of type 2 diabetes in children (0-19 y) has increased 4-fold. Although the etiology of obesity related impairement of glucose metabolism is multifactorial, dietary macronutrient intake and physical activity are potentially important factors. The aims of this proposal are to determine in healthy adolescents 1) the impact of obesity on energy expenditure and substrate oxidation, glucose production from gluconeogenesis and glycogenolysis, insulin secretion and sensitivity, and lipolysis; 2) whether a 12 weeks resistance training exercise program will improve glucose metabolism in obese adolescents, and if so, 3) whether the exercise effect is correlated with a decrease in total intramyocellular, visceral and/or hepatic fat content. To address these questions, 12 over weight (body fat >30%) and 12 lean (body fat <25%) adolecents will be studied on two occasions (just prior to the start of a 12 weeks exercise program and at the end of the last week of exercise); in all subjects, each of the two study occasions will be preceded by 7-d of a high fat diet. State of the art stable isotope-GCMS techniques and MRI will be sued to obtain the data needed to address the aims stated above. The information provided by these studies will improve our understanding of the metabolic effects of obesity in adolescents, will lead to identifying factors which may increase, prvent or delay the development of type 2 diabetes. It will also help us determine whether strength exercise without intent to weight loss will improve insulin sensitivity and normalize glucose metabolism in over weight adolescents. HYPOTHESIS Overall hypotheses: Resistance training exercise (without intent of weight loss) improves insulin sensitivity, normalizes glucose metabolism and reduces intramyocellular, visceral and hepatic fat in healthy obese adolescents. Specific hypotheses: H1. A 12 weeks resistance exercise program (x 2/week, 1 h/session) increases insulin sensitivity in obese adolescents, but not in already insulin sensitive lean adolescents. H2. The exercise-induced changes in insulin snesitivity are inversely correlated with exercise-induced changes in intramyocellular fat content. H3. A 12 weeks resistance exercise program will normalize gluconeogenesis in obese adolescents by reducing hepatic fat accumulation. SPECIFIC AIMS To determine whether a 12 weeks resitance training exercise program (x 2/week; 1 h/session) would increase insulin sensitivity, reduce gluconeogenesis and decrease intramyocellular and hepatic fat content in obese adolescents.