DHEA REPLACEMENT AND RESISTANCE EXERCISE IN THE ELDERLY

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 衰老与肌肉质量的损失有关。鉴于肌肉质量和骨矿物质密度（BMD）之间的密切关系，有必要采取干预措施，以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，肌肉质量的损失可能使老年人容易患肥胖症和2型糖尿病。老年人可以通过抗阻运动训练（雷克斯）显着增加肌肉力量，但FFM的增益通常是适度的（约2磅或1公斤），并且小于年轻人的增益。这项研究的工作模型是，老年人的合成代谢（“建筑”）激素水平低，限制了雷克斯在FFM中的收益。脱氢表雄酮（DHEA）是一种由肾上腺分泌的激素，随着年龄的增长而减少。在以前的研究中，口服DHEA替代品（50 mg/天）将老年人的血液DHEA-硫酸盐增加到年轻人的水平，并增加FFM和BMD。因此，研究假设是，老年人的DHEA替代将提供足够的合成代谢支持，以增加FFM和BMD的增加，以响应雷克斯。为了验证这一假设，将招募20名年龄大于60岁的健康女性和男性，以完成为期6个月的雷克斯和DHEA替代干预。在开始雷克斯之前，志愿者将完成为期12个月的DHEA替代研究（GCRC方案#1195）。志愿者被随机分配服用DHEA替代品（50 mg/天）或安慰剂。这些分配将再持续6个月，并将保持双盲。研究组为雷克斯+DHEA和雷克斯+安慰剂。雷克斯将是每周3天，高强度（最大强度的80%），使用7个练习。将通过双能X线吸收测定法、腹部和大腿中部区域的计算机断层扫描（CT）和周长测量确定身体组成。 肌肉质量将通过一次重复最大力量测试、连续量表身体功能表现测试和胰岛素作用的口服葡萄糖耐量测试来确定。将检查与血清合成代谢激素和生长因子水平相关的身体组成和肌肉质量变化。

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.