Physical Activity in Overweight Girls: Implications for Reversing Risk Factors fo

描述（由申请人提供）：儿童肥胖是一个主要的公共卫生问题，因为超重的青少年患有胰岛素抵抗、2型糖尿病（T2DM）、代谢综合征和心血管疾病等合并症，这些疾病曾经被认为是成年人独有的。虽然儿童肥胖的原因尚不清楚，但体力活动减少是一个主要因素。在成人中，有规律的PA（150分钟/周）或30分钟/天，持续5-7天/周与显著降低肥胖和预防2型糖尿病相关。然而，在超重女孩中，单独使用这种水平的PA（不限制卡路里）对腹部肥胖、异位脂肪和2型糖尿病危险因素的潜在益处尚不清楚。因此，我们将研究超重女孩在不限制卡路里的情况下进行定期运动对以下方面的影响：1)使用钳夹技术进行体内胰岛素敏感性和分泌以及T2DM的风险；2)使用全身磁共振成像检测全身和腹部脂肪；3)利用1h磁共振波谱分析肝脏和骨骼肌中的异位脂肪。更具体地说，我们将比较不同的运动方式（有氧运动与阻力运动）对这些健康指标的影响，并探讨规律运动介导T2DM相关健康风险改善的潜在机制。我们将招募42名久坐不动的超重黑人和白人女孩，并将她们随机分配到三个为期3个月的干预组之一：有氧训练（每周180分钟），阻力训练（每周180分钟）或无运动控制。我们相信，这项研究的结果将对以证据为基础的公共卫生和临床指南的发展具有重要意义，有助于我们努力对抗当前流行的儿童肥胖。

DESCRIPTION (provided by applicant): Childhood obesity is a leading public health concern because overweight youth suffer from co-morbidities such as insulin resistance, type 2 diabetes mellitus (T2DM), metabolic syndrome and cardiovascular disease, conditions once considered unique to adults. Although the causes of childhood obesity are not clear, decreased physical activity (PA) is a major factor. In adults, it is well established that regular PA (>150 min/wk) or 30 min/day of PA for 5-7 days/wk is associated with significant reductions in adiposity and prevention of T2DM. However, the potential benefits of this level of PA alone (without calorie restriction) on abdominal obesity, ectopic fat and risk factors for T2DM are unclear in overweight girls. Therefore, we will examine the effects of regular exercise without calorie restriction in overweight girls on: 1) in vivo insulin sensitivity and secretion and risk of T2DM using the clamp technique; 2) total and abdominal adiposity using whole body magnetic resonance imaging; 3) ectopic fat in the liver and skeletal muscle using 1H-magnetic resonance spectroscopy. More specifically, we will compare the effects of different exercise modalities (aerobic exercise versus resistance exercise) on these health markers, and explore the potential mechanisms by which regular exercise mediates improvements in health risks associated with T2DM. We will recruit 42 sedentary overweight black and white girls, and randomly assign them to one of three 3-month intervention groups: aerobic training (180 min per week), resistance training (180 min per week), or no-exercise control. We believe that the results of this study will be of significance for the development of evidence-based public health and clinical guidelines in our efforts to combat the current epidemic of childhood obesity. PUBLIC HEALTH RELEVANCE: We will examine the effect of a 3-month exercise training (aerobic exercise versus resistance exercise) without dieting on obesity reduction, and improving fitness, body composition and risk of type 2 diabetes in overweight black and white girls.