AGE, SEX & BALANCE BTW CARDIAC OUTPUT & MUSCLE BLOOD FLOW IN EXERCISING HUMANS

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。 与年轻人相比，久坐不动的老年人通过将更高比例的心输出量引导到工作肢体并具有夸大的升压反应来保持工作肌肉的血流量。 相反，老年妇女不能保持腿部血流量在直立骑自行车运动，并试图优化腿部血流量，甚至进一步夸大升压反应在直立运动。 本方案将解决这一问题，以确定衰老对老年人运动肌肉灌注需求和心脏泵送能力之间相互作用的影响。 此外，研究的受试者组将包括足够的样本量，以评估每个测量变量中的年龄-性别相互作用，这是人类生理学中很少采用的方法论观点。 假设：当外推至整个肢体肌肉质量时，老年女性和男性在最大单腿伸展运动期间测量的峰值灌注将超过老年女性和男性的心脏泵送能力，其程度大于年轻性别匹配的受试者，表明老年女性和男性更需要血管收缩工作骨骼肌。

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. Older sedentary men preserve blood flow to the working muscles by directing a higher percentage of their cardiac output to the working limbs and having an exaggerated pressor response relative to young men. In contrast, aged women cannot maintain leg blood flow during upright cycling exercise and attempt to optimize leg blood flow by an even further exaggerated pressor response during upright exercise. This protocol will address this issue to determine the effect of aging on the interplay between exercising muscle demand for perfusion and the pumping capacity of the heart in aged humans. Additionally, the subject groups studied will consist of sufficient sample sizes to assess ageXsex interactions in each of the variables measured, a methodological perspective rarely taken in human physiology. Hypothesis: The peak perfusion measured during maximal single leg extension exercise in aged women and men, when extrapolated to the entire limb muscle mass, will exceed the cardiac pumping capacity by a greater degree in the older women and men than younger sex-matched subjects indicating a greater need to vasoconstrict working skeletal muscle in aged women and men.