Anabolic Versus Catabolic Skeletal Effects of Endurance or Resistance Exercise in Older Veterans

经常建议运动以降低骨质疏松性骨折的风险。然而，骨不 总是导致预期的骨质改善，有证据表明，耐力运动可能 在某些情况下导致骨质流失。我们的论点是， 运动，导致血清离子钙（伊卡）降低和甲状旁腺激素（PTH）升高 和I型胶原蛋白的C-端肽（CTX;骨吸收的标志物），其发生在骨吸收开始后不久。 运动，可能是缺乏骨矿物质密度的预期改善的原因。伊卡， PTH和CTX对运动的反应已经在年轻人和老年人中得到了很好的表征， 对单次耐力运动回合的反应，但目前还不清楚阻力训练（例如，举重）结果 在同样的运动引起的钙稳态的破坏。此外，尚不清楚伊卡、PTH和 CTX对运动的反应可能会随着运动训练而改变，如果对运动的骨合成代谢反应可以 在重复运动后被检测到。骨合成代谢对运动的反应（通过前胶原评估） I型末端前肽，P1 NP;骨形成的标志物）尚未被完全表征，但这可能 这是由于单次运动测试和运动后的短采样时间轴。解决 由于这些知识差距，最多60名年龄在60-80岁之间的退伍军人（30名男性，30名女性）将被随机分配至1） 固定自行车;或2）阻力训练，并将完成10周的监督运动训练，每周3次 (30总的运动训练课程）。演习次数增加是因为 P1 NP在28剂量的特立帕鲁肽（一种PTH类似物）后，导致骨形成。在1日、15日和30日期间， 在运动训练课程中，参与者将在运动前和运动后进行急性运动测试 运动后48小时内取样。将采集血液样本以测量伊卡、PTH、CTX和P1 NP。 主要目的是1）确定抗阻运动是否导致不同的骨生物标志物反应 与我们在老年人耐力运动中观察到的情况相比; 2）确定阻力是否 和/或耐力运动导致P1 NP在10周的运动训练中增加。探索性 与健康和功能状态变化相关的结果将解决退伍军人健康如何受到 每种练习类型，将用于通知未来的应用程序。生物标志物和功能结局 信息是确定适当的运动“剂量”的下一步，包括以下因素， 运动类型，频率，持续时间和强度（将在未来的研究中探索），可用于 增强退伍军人的健康。运动应该继续被推荐用于整体健康，但未来 干预措施可以包括已知的心脏代谢所需的运动剂量， 健康和新兴的数据，需要锻炼的剂量，以保持骨骼健康，创造个性化的 运动处方，以改善退伍军人健康的多个组成部分。所提出的研究是有意义的 因为它正在调查需要解决的几个知识差距，以设计未来更大的演习 和生活方式干预，旨在保护退伍军人健康的多个组成部分，这可能有一个 对退伍军人生活质量和功能独立性的持久影响。该研究具有创新性 因为它是测试新的假设，运动模式对钙稳态的破坏和 运动训练的作用，在人口中，可以大大受益于所获得的知识。长期来看， 从这项研究中收集的信息将有助于定义个性化的运动处方， 心脏代谢健康而不影响老年退伍军人的骨骼健康。

Exercise is frequently recommended to reduce the risk of osteoporotic fracture. However, bone does not always result in the expected improvements in bone mass, and there is evidence that endurance exercise may lead to bone loss under certain conditions. It is our contention that disruptions in calcium homeostasis during exercise, resulting in a decrease in serum ionized calcium (iCa) and increases in parathyroid hormone (PTH) and c-telopeptide of type I collagen (CTX; a marker of bone resorption) that occur shortly after the start of exercise, may be responsible for the lack of the expected improvements in bone mineral density. The iCa, PTH, and CTX responses to exercise have been well-characterized for both young and older adults in response to a single endurance exercise bout, but it is unclear if resistance training (e.g., weightlifting) results in the same exercise-induced disruption in calcium homeostasis. Further, it is unclear how the iCa, PTH, and CTX response to exercise may change with exercise training, and if a bone anabolic response to exercise can be detected after repeat exercise bouts. The bone anabolic response to exercise (assessed by procollagen of type I terminal propeptide, P1NP; a marker of bone formation) has yet to be fully characterized, but that may be due to the testing of single exercise bouts and the short sampling timeline following exercise. To address these gaps in knowledge, up to 60 Veterans (30 men, 30 women), aged 60-80 years, will be randomized to 1) stationary cycling; or 2) resistance training and will complete 10 weeks of supervised exercise training 3x/week (30 total exercise training sessions). This number of exercise visits was due to the demonstrated increase in P1NP after 28 doses of teriparatide, a PTH analog, that results in bone formation. During the 1st, 15th, and 30th exercise training session, participants will undergo an acute exercise testing bout with pre- and post-exercise sampling up to 48 hours after exercise. Blood samples will be collected to measure iCa, PTH, CTX and P1NP. The primary aims are 1) to determine if resistance exercise results in a different bone biomarker response compared to what we have observed during endurance exercise in older adults; 2) determine if resistance and/or endurance exercise result in an increase in P1NP over 10 weeks of exercise training. Exploratory outcomes related to changes in fitness and functional status will address how Veteran health is impacted by each exercise type, which will be used to inform future applications. The biomarker and functional outcomes information are the next step in determining the appropriate “dose” of exercise, consisting of factors such as exercise type, frequency, duration, and intensity (which will be explored in future research), can be used to enhance Veteran health. Exercise should continue to be recommended for overall health, but future interventions could incorporate what is known about the dose of exercise that is needed for cardiometabolic health and the emerging data on the dose of exercise needed to preserve bone health to create personalized exercise prescriptions to improve multiple components of Veteran health. The proposed research is significant because it is investigating several knowledge gaps that need to be addressed to design future, larger exercise and lifestyle interventions aimed at preserving multiple components of Veteran health, which could have a lasting impact on Veteran quality of life and functional independence. The proposed research is innovative because it is testing novel hypotheses, the mode of exercise on the disruption in calcium homeostasis and the role of exercise training, in a population that could greatly benefit from the knowledge to be gained. Long-term, information gleaned from this research will help to define personalized exercise prescriptions to improve cardiometabolic health without compromising bone health in aging Veterans.