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

运动经常被推荐用来降低骨质疏松性骨折的风险。然而，骨骼不能 总是导致预期的骨量改善，而且有证据表明耐力锻炼可能 在某些情况下会导致骨质流失。我们的论点是钙稳态的破坏在 运动导致血清离子钙(ICA)降低和甲状旁腺激素(PTH)升高 和I型胶原c-端肽(CTX；骨吸收的标志)，在开始后不久出现 运动，可能是缺乏预期的骨密度改善的原因。ICA， PTH和CTX对运动的反应在年轻人和老年人中都得到了很好的表征 对单次耐力运动的反应，但尚不清楚阻力训练(例如举重)是否会产生效果 在相同的运动引起的钙稳态的破坏。此外，尚不清楚ICA、PTH和 CTX对运动的反应可能会随着运动训练而改变，如果对运动的骨骼合成代谢反应可以 在重复的运动后被检测到。运动引起的骨合成代谢反应(用前胶原测定) I型末端前肽，P1NP；骨形成的标志)尚未完全表征，但可能 这是由于单次练习的测试和练习后抽样时间较短所致。致信地址 这些知识差距，多达60名退伍军人(30名男性，30名女性)，年龄在60-80岁之间，将随机分为1人) 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 (共30次运动训练)。这一演习访问次数是由于 甲状旁腺素类似物--特立帕帝28剂后的P1NP，可导致骨形成。在第1、第15和第30天 运动训练环节，参与者将在运动前和运动后进行一次急性运动测试 在运动后48小时内取样。采集血样测定ICA、PTH、CTX和P1NP。 主要目的是1)确定抗阻运动是否会导致不同的骨骼生物标记物反应 与我们在老年人耐力运动中观察到的情况进行比较；2)确定阻力是否 和/或耐力运动导致P1NP在10周的运动训练中增加。探索性的 与健康和机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，将用于通知未来的申请。生物标记物与功能结局 信息是确定适当的运动“剂量”的下一步，包括以下因素 锻炼的类型、频率、持续时间和强度(将在未来的研究中探索)可以用来 增强退伍军人健康水平。运动应该继续被推荐用于整体健康，但在未来 干预措施可以包括已知的心脏代谢所需的运动量。 健康和关于保持骨骼健康所需运动量的新兴数据创建个性化 运动处方，改善退伍军人健康的多个组成部分。这项拟议的研究具有重要意义 因为它正在调查几个需要解决的知识差距，以设计未来更大的练习 以及旨在保护退伍军人健康的多个组成部分的生活方式干预，这可能会有 对退伍军人的生活质量和功能独立性的持久影响。建议的研究具有创新性。 因为它测试了新的假说，运动模式对钙稳态的破坏和 运动训练的作用，在一个可以从所获得的知识中获得极大好处的人群中。从长远来看， 从这项研究中收集的信息将有助于确定个性化的运动处方，以提高 在不损害老年退伍军人骨骼健康的情况下保持心脏代谢健康。

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.