Comparison of Exercise Mode on Disruptions in Calcium Homeostasis

耐力运动经常被推荐为降低心脏代谢疾病风险的一种手段 并降低骨质疏松性骨折的风险。然而，骨骼并不总是以这种方式适应， 预期，有证据表明，耐力运动可能会导致骨质流失在某些条件下。是 我们的论点是，在运动过程中钙稳态的破坏，导致血清离子化水平的降低， 钙（伊卡）和甲状旁腺激素（PTH）和I型胶原蛋白C端肽（CTX;一种标志物）升高 骨吸收），可能是缺乏改善骨矿物质的原因 预期的密度。这一领域的急性研究主要集中在年轻健康的成年人身上， 主要是男性，在固定的自行车运动。很少有研究是在老年人中进行的，但那些 研究发现，老年人在钙稳态中经历类似的破坏， 剧烈的耐力训练初步比较我们的研究，以及其他实验室的研究， 还表明，在这些急性运动发作期间进行的运动模式可能是一个重要的 运动分解代谢骨骼反应的决定因素。看来，负重锻炼（即， 跑步机）导致PTH和CTX的较小增加（即，固定 循环）。这从未使用受试者内设计进行过测试，因此尚不清楚是否观察到这些结果。 差异是由于运动模式、实验室间差异或其他潜在因素造成的。为了解决这个 在知识的差距，30名退伍军人（15名男性，15名女性），年龄60岁以上，将完成两个1小时的急性运动 比赛：1）以最大心率的70-80%在跑步机上快速行走; 2）以最大心率的70-80%在剧烈的静止自行车运动中 最大心率将采集血液样本，以测量伊卡、PTH、CTX和I型前胶原。 末端前肽（P1 NP）在每次运动之前、期间和之后。运动回合的顺序将 是随机的和平衡的。主要目的是确定运动模式是否会导致 老年退伍军人的骨生物标志物反应差异。这些信息对于理解如何 未来的运动干预措施应设计为有益于心脏代谢健康和骨骼健康。这 由于两种心脏代谢疾病的高负担（例如， 糖尿病、心脏病）以及骨质疏松性骨折风险增加的证据。的 拟议的研究是重要的，因为它正在解决知识差距，阻碍了能力， 设计运动和生活方式干预措施，旨在保护退伍军人健康的多个组成部分， 可能对退伍军人的生活质量和功能独立性产生持久影响。拟议的研究是 创新，因为它正在测试一个新的假设，运动模式对钙的干扰 内稳态，在一个可以从所获得的知识中受益匪浅的人群中。虽然拟议的 研究是一项急性研究，产生的结果将用于设计未来的退伍军人临床干预措施。 健康从长远来看，从这项研究中获得的信息将有助于确定最佳的运动处方， 改善心脏代谢，而不损害骨骼健康老化退伍军人。

Endurance exercise is frequently recommended as a means to reduce the risk of cardiometabolic diseases and to reduce the risk of osteoporotic fracture. However, bone does not always adapt in the way that would be expected, 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 decreases in serum ionized calcium (iCa) and increases in parathyroid hormone (PTH) and c-telopeptide of type I collagen (CTX; a marker of bone resorption) at the onset of exercise, may be responsible for the lack of improvements in bone mineral density that are anticipated. Acute studies in this area have predominantly focused on young, healthy adults, primarily men, during stationary cycling exercise. Few studies have been conducted in older adults, but those studies have found that older adults experience similar disruptions in calcium homeostasis in response to an acute bout of endurance exercise. Preliminary comparisons of our studies, as well as research from other labs, also suggests that that mode of exercise conducted during these acute exercise bouts may be an important determining factor in the catabolic bone response to exercise. It appears that weight-bearing exercise (i.e., treadmill) results in smaller increases in PTH and CTX compared to weight-supported exercise (i.e., stationary cycling). This has never been tested using a within-subjects design, so it is unclear if these observed differences are due to the mode of exercise, lab-to-lab differences, or other underlying factors. To address this gap in knowledge, 30 Veterans (15 men, 15 women), aged 60+ years, will complete two 1-hour acute exercise bouts: 1) brisk treadmill walking at 70-80% of maximal heart rate; 2) vigorous stationary cycling at 70-80% maximal heart rate. Blood samples will be collected to measure iCa, PTH, CTX and procollagen type I n- terminal propeptide (P1NP) before, during, and after each exercise bout. The order of the exercise bouts will be randomized and counter-balanced. The primary aim is to determine if mode of exercise results in a differential bone biomarker response in older Veterans. This information is essential for understanding how future exercise interventions should be designed to benefit both cardiometabolic health and bone health. This is especially relevant to Veteran health due to the high burden of both cardiometabolic diseases (e.g., diabetes, heart disease) in the population, as well as evidence of increased osteoporotic fracture risk. The proposed research is significant because it is addressing a knowledge gap that has prevented the ability to design 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 a novel hypothesis, the mode of exercise on disruptions in calcium homeostasis, in a population that could greatly benefit from the knowledge to be gained. While the proposed research is an acute study, the results generated will be used to design future clinical interventions for Veteran health. Long-term, information gained from this research will help to define the optimal exercise prescription to improve cardiometabolic without compromising bone health aging Veterans.