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性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 这是意料之中的，而且有证据表明，在某些条件下，耐力运动可能会导致骨质流失。它是 我们的观点认为，运动过程中钙稳态的破坏会导致血清中离子浓度的降低 钙(ICA)、甲状旁腺激素(PTH)和I型胶原c-端肽(CTX；标志物)的增加 骨吸收)，可能是导致骨矿物质缺乏改善的原因 预期的密度。这一领域的尖锐研究主要集中在年轻、健康的成年人身上， 主要是男性，在静态自行车运动中。很少有研究在老年人身上进行，但那些 研究发现，老年人在钙稳态方面经历了类似的紊乱，以应对 一场剧烈的耐力运动。对我们的研究以及其他实验室的研究进行了初步比较， 这也表明，在这些激烈的运动比赛中进行的运动模式可能是一个重要的 运动对分解代谢骨反应的决定因素。看起来负重锻炼(即， 与负重运动(即静止运动)相比，跑步机运动导致甲状旁腺素和环磷酰胺的增加较小 骑自行车)。这从未使用受试者内部设计进行过测试，因此不清楚是否观察到这些 差异是由于锻炼方式、实验室之间的差异或其他潜在因素造成的。要解决这个问题 知识差距，30名60岁以上的退伍军人(15男15女)将完成两个1小时的急性运动 比赛：1)以最大心率的70%-80%在跑步机上快步行走；2)以70%-80%的速度进行剧烈的静止自行车 最大心率。将采集血样检测ICA、PTH、CTX和前胶原型。 运动前、运动中、运动后的末端前肽(P1NP)。演习的顺序是 随机化和制衡。主要目的是确定锻炼方式是否会导致 老年退伍军人的不同骨生物标记物反应。这些信息对于理解如何 未来的运动干预应该设计成对心脏代谢健康和骨骼健康都有好处。这 由于心脏代谢性疾病的高负担(例如， 糖尿病、心脏病)，以及骨质疏松性骨折风险增加的证据。这个 拟议的研究具有重要意义，因为它正在解决一个知识鸿沟，这个鸿沟阻碍了 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， 可能会对退伍军人的生活质量和功能独立性产生持久的影响。拟议的研究是 创新是因为它测试了一个新的假说，即运动模式对钙离子干扰的影响 动态平衡，在一个可以从即将获得的知识中获得极大好处的人群中。虽然建议的 研究是一项尖锐的研究，所产生的结果将用于为退伍军人设计未来的临床干预措施 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运动处方 在不影响骨骼健康的情况下改善心脏代谢老化退伍军人。

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.