DHEA REPLACEMENT AND RESISTANCE EXERCISE IN THE ELDERLY

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。 衰老与肌肉质量的丧失有关。鉴于肌肉质量和骨密度(BMD)之间的密切联系，有必要采取干预措施增加老年人的无脂肪质量(FFM)，以防止虚弱和功能独立性的丧失。此外，肌肉质量的丧失可能使老年人易患肥胖症和2型糖尿病。老年人可以通过阻力运动训练(REX)显著增加肌肉力量，但FFM的增加通常不大(约2磅或1公斤)，而且比年轻人少。这项拟议研究的工作模式是，老年人体内低水平的合成代谢激素限制了服用REX的FFM的收益。脱氢表雄酮(DHEA)是肾上腺分泌的一种激素，随着年龄的增长，其分泌量逐渐减少。在先前的研究中，口服DHEA替代药物(50毫克/天)使老年人的血液DHEA-硫酸盐水平增加到年轻人的水平，并增加了FFM和BMD。因此，研究假设是，在老年人中替代DHEA将提供足够的合成代谢支持，以增加对REX的FFM和BMD的增加。为了验证这一假设，20名60岁以上的健康女性和男性将被招募来完成为期6个月的REX和DHEA替代干预。志愿者将在开始REX之前完成为期12个月的DHEA替代研究(GCRC方案#1195)。志愿者被随机分配到服用脱氢表雄酮替代品(50毫克/天)或安慰剂。这些任务将再持续6个月，并将保持双盲状态。研究组将是REX+DHEA和REX+安慰剂。霸王龙将每周3天，高强度(最大强度的80%)，使用7个练习。身体成分将通过双能量X射线吸收法、腹部和大腿中部的计算机断层扫描(CT)扫描和周长测量来确定。肌肉质量将通过一次重复的最大强度测试、连续规模的身体机能测试和口服葡萄糖耐量测试来确定胰岛素的作用。将检查身体成分和肌肉质量的变化与血清合成激素和生长因子水平的关系。

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. Aging is associated with a loss of muscle mass. Given the close association between muscle mass and bone mineral density (BMD), interventions to increase fat-free mass (FFM) in the elderly are necessary to prevent frailty and loss of functional independence. Furthermore, loss of muscle mass may predispose the older adult to obesity and Type 2 diabetes. Older adults can achieve significant increases in muscular strength in response to resistance exercise training (REX) but gains in FFM are typically modest (about 2 lbs or 1 kg) and less than those achieved by younger adults. The working model for the proposed study is that low levels of anabolic ("building") hormones in older adults limit the gains in FFM with REX. Dehydroepiandrosterone (DHEA) is a hormone secreted by the adrenal gland in diminishing amounts with advancing age. In previous studies, oral DHEA replacement (50 mg/day) increased blood DHEA-sulfate in older adults to young adult levels, and increased FFM and BMD. Thus the research hypothesis is that DHEA replacement in older adults will provide sufficient anabolic support to add to the increases in FFM and BMD in response to REX. To test this hypothesis, 20 healthy women and men, greater than 60 years old, will be recruited to complete a 6-month intervention of REX and DHEA replacement. The volunteers will have completed a 12-month study of DHEA replacement (GCRC protocol #1195) before starting REX. The volunteers were randomly assigned to take DHEA replacement (50 mg/day) or placebo. These assignments will continue for an additional 6 months, and will remain double-blinded. The study groups will be REX+DHEA and REX+placebo. REX will be 3 days per week, of high intensity (80% of maximum strength), using 7 exercises. Body composition will be determined by dual energy x-ray absorptiometry, computed tomography (CT) scans of the abdomen and mid-thigh areas, and circumference measurements. Muscle quality will be determined by one-repetition maximum strength tests, the Continuous-Scale Physical Functional Performance test, and oral glucose tolerance tests for insulin action. Changes in body composition and muscle quality in relation to serum levels of anabolic hormones and growth factors will be examined.