Thermoregulatory function in euhydrated and dehydrated obese individuals

水合和脱水肥胖个体的体温调节功能

• 批准号: 8106297
• 负责人: Matthew Ganio
• 金额: $ 1.12万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-14 至 2011-08-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8106297
• 关键词: Acetylcholine; Acute; Adult; Adverse effects; American; Attenuated; Belief; Blood Pressure; Blood flow; Body Temperature; Body Weight decreased; Cardiac Output; Cardiovascular system; Clinical; Communities; Data; Dehydration; Disease; Electric Capacitance; Epidemiologic Studies; Exercise; Failure; Fatigue; Fever; Generations; Goals; Heart Rate; Heat Losses; Heating; Homeostasis; Impairment; Increased sweating; Individual; Injury; Intestines; Laboratory Study; Lead; Life; Life Style; Liquid substance; Measures; Medical; Membrane; Microdialysis; Modeling; Motivation; Neurotransmitters; Nitric Oxide Donors; Non obese; Obesity; Oxygen; Physiologic Thermoregulation; Physiological; Population Study; Protocols documentation; Public Health; Recommendation; Regimen; Regulation; Risk; Series; Skin; Skin Temperature; Sports Medicine; Stimulus; Stress; Stroke Volume; Sweat; Sweat Glands; Sweating; Temperature; Testing; Thermogenesis; Vasodilator Agents; Weight; body water loss; college; cost; high risk; insight; premature; psychologic; public health relevance; response; subcutaneous; uptake

DESCRIPTION (provided by applicant): With 1/3 of the US adult population obese, the medical cost of obesity is $147 billion dollars per year. Exercise is one of the major lifestyle changes recommended to lose weight. To lose significant weight, the American College of Sports Medicine recommends >250 minutes of exercise per week. Exercise will increase body temperature, especially when it is performed at a high intensity or in the heat. Increased body temperature, or hyperthermia, leads to sweating and dehydration. Dehydration and hyperthermia increase physiological and psychological fatigue, both of which can cause premature exercise fatigue resulting in exercise cessation during the acute exercise bout as well as reduce motivation to continue a life-long exercise regimen. This failure to exercise will be counterproductive to weight loss goals and the cardiovascular benefits of exercise. Despite obesity often cited as a contributing factor to hyperthermia and heat illnesses, findings from laboratory studies investigating thermoregulatory control in obese individuals are mixed, likely because these studies did not take into consideration differences in heat generation during exercise between obese and non-obese groups. The primary objective of this project is to examine the effects of obesity on thermoregulatory control to exercise in the heat. Specific Aim 1 will test the hypothesis that overall thermoregulatory responses to exercise in the heat when euhydrated will be impaired in obese compared to non-obese individuals. Sweat rate, intestinal temperature, skin blood flow, cardiac output, stroke volume, heart rate, and blood pressure will be measured while both groups perform prolonged exercise at equal levels of oxygen uptake, and thus equal heat production. Subjects will begin and remain euhydrated throughout exercise. Specific Aim 2 will test the hypothesis that dehydration has a greater adverse effect on thermoregulatory function in obese versus non-obese individuals. The same measures will be obtained as Aim 1 while subjects undergo the same exercise protocol. However, prior to testing, subjects will be 3% dehydrated (i.e., reduction of 3% body mass) by performing an exercise and heat exposure. Specific Aim 3 will identify mechanisms responsible for modified thermoregulatory responses in obese individuals. Specifically, we will identify the mechanisms responsible for attenuated skin blood flow and increased local sweat rate responses in obese individuals while euhydratad. These questions will be answered by performing a series of mechanistic studies using subcutaneous microdialysis membranes and administration of local vasodilators (nitric oxide donor and acetylcholine) and sweat gland stimulates (acetylcholine).The information gained from the proposed project will provide valuable data to aid in understanding the effects of obesity on exercise thermoregulation and could alter fluid replacement and exercise recommendations for obese individuals. PUBLIC HEALTH RELEVANCE: Although population studies suggest that obese individuals, compared to their lean counterparts, are at an increased risk for high body temperature, there is very little scientific data to support the public and scientific belief that obese individuals "store heat" or heat up quicker when exercising. In order to promote public health and the loss of weight for the 72 million obese Americans, it is imperative that the scientific community understands the precise magnitude and mechanisms of cardiovascular and body temperature control in obese individuals. The proposed project will identify how obese individuals control body temperature while exercising and will provide insight into understanding a previously unidentified barrier for obese individuals to achieve the degree of exercise stimulus needed to decrease body weight.

描述（由申请人提供）：在美国成年人肥胖的1/3中，肥胖症的医疗费用为每年1470亿美元。运动是建议减肥的主要生活方式变化之一。为了减轻体重，美国运动医学学院建议每周进行250分钟的运动。运动会提高体温，尤其是在高强度或热量中进行的运动时。体温或高温升高会导致出汗和脱水。脱水和高温增加了生理和心理疲劳，这两种疲劳都会导致过早的运动疲劳，从而导致急性运动期间的运动停止，并减少继续进行终身运动方案的动力。这种失败的运动将对减肥目标和运动的心血管益处适得其反。尽管肥胖通常被认为是对高温和热病疾病的促成因素，但实验室研究的发现，研究了肥胖个体的温度调节控制的结果，可能是混合的，可能是因为这些研究在肥胖和非肥胖群体之间运动过程中没有考虑到在运动过程中产生差异。该项目的主要目的是检查肥胖对在热量中运动的影响。具体的目标1将检验以下假设：与非肥胖个体相比，肥胖的欧亚水会损害时，对热量运动的总体体温调节反应会受到损害。出汗率，肠道温度，皮肤血流，心脏输出，中风体积，心率和血压将被测量，而两组则在相等的氧气吸收水平上进行延长运动，从而等同的产生。在整个运动中，受试者将开始并保持欧水。具体目标2将检验以下假设：脱水对肥胖和非肥胖个体的热调节功能具有更大的不利影响。同样的措施将作为AIM 1获得，而受试者进行相同的练习方案。但是，在测试之前，通过进行运动和热暴露，受试者将脱水3％（即减少3％体重）。具体目标3将确定负责肥胖个体改良温度调节反应的机制。具体而言，我们将确定负责减弱皮肤血流的机制，并增加肥胖个体的局部汗液率反应。这些问题将通过使用皮下微透析膜和局部血管舒张剂（一氧化氮供体和乙酰胆碱）进行一系列机械研究来解决这些问题，并刺激汗腺（乙酰胆碱）（乙酰胆碱）。为拟议的项目提供的信息将有助于理解效果的有价值的效果，并可能对运动的效果进行效果，并能够效应肥胖症的效果，以实现肥胖的效果。个人。 公共卫生相关性：尽管人口研究表明，与瘦弱的人相比，肥胖的人的体温有所增加，但几乎没有科学数据来支持公众和科学的信念，即肥胖的个体“储存热”或在运动时更快地加热。为了促进公共卫生和7200万肥胖美国人的体重减轻，科学界必须了解肥胖个体的心血管和体温控制的确切规模和机制。拟议的项目将确定肥胖个体在运动时如何控制体温，并可以洞悉理解以前未知的障碍，以使肥胖个体达到减轻体重所需的运动刺激程度。