Abstract：
Aging is associated with a significant decline in aerobic capacity assessed by maximal exercise oxygen consumption (V̇o2max). The relative contributions of the specific V̇o2 components driving this decline, namely cardiac output (CO) and arteriovenous oxygen difference (A - V)O2, remain unclear. We examined this issue by analyzing data from 99 community-dwelling participants (baseline age: 21-96 yr old; average follow-up: 12.6 yr old) from the Baltimore Longitudinal Study of Aging, free of clinical cardiovascular disease. V̇o2peak, a surrogate of V̇o2max, was used to assess aerobic capacity during upright cycle ergometry. Peak exercise left ventricular volumes, heart rate, and CO were estimated using repeated gated cardiac blood pool scans. The Fick equation was used to calculate (A - V)O2diff,peak from COpeak and V̇o2peak. In unadjusted models, V̇o2peak, (A - V)O2diff,peak, and COpeak declined longitudinally over time at steady rates with advancing age. In multiple linear regression models adjusting for baseline values and peak workload, however, steeper declines in V̇o2peak and (A - V)O2diff,peak were observed with advanced entry age but not in COpeak. The association between the declines in V̇o2peak and (A - V)O2diff,peak was stronger among those ≥50 yr old compared with their younger counterparts, but the difference between the two age groups did not reach statistical significance. These findings suggest that age-associated impairment of peripheral oxygen utilization during maximal exercise poses a stronger limitation on peak V̇o2 than that of CO. Future studies examining interventions targeting the structure and function of peripheral muscles and their vasculature to mitigate age-associated declines in (A - V)O2diff are warranted.NEW & NOTEWORTHY The age-associated decline in aerobic exercise performance over an average of 13 yr in community-dwelling healthy individuals is more closely associated with decreased peripheral oxygen utilization rather than decreased cardiac output. This association was more evident in older than younger individuals. These findings suggest that future studies with larger samples examine whether these associations vary across the age range and whether the decline in cardiac output plays a greater role earlier in life. In addition, studies focused on determinants of peripheral oxygen uptake by exercising muscle may guide the selection of preventive strategies designed to maintain physical fitness with advancing age.
摘要：
衰老与通过最大运动耗氧量（VO2-max）评估的运动适应性显着下降有关。驱动这种下降的特定VO2-max成分，即心输出量（CO）和动静脉氧差（A-V）O2尚不清楚。我们通过分析来自巴尔的摩老龄化纵向研究的99名社区居住参与者（基线年龄21-96岁；平均随访12.6年）的数据来研究这个问题，无临床心血管疾病。VO2-峰值,VO2-max的替代品，用于评估直立循环运动期间的有氧能力。运动左心室(LV)容积峰值,心率,和心输出量使用重复门控心脏血池扫描进行估计。Fick方程用于从CO峰和VO2峰计算(A-V)O2峰。在未调整的模型中，VO2-峰值,(A-V)O2-峰值,随着年龄的增长，CO峰以稳定的速度随时间纵向下降。在调整基线值和峰值工作量的多元线性回归模型中，然而,随着年龄的增长，观察到VO2峰值和（A-V）O2峰值的急剧下降，而不是CO峰值。与年轻人相比，>=50岁的人群中VO2峰值和（A-V）O2峰值下降之间的关联更强，但两个年龄组之间的差异未达到统计学意义。这些发现表明，最大运动期间与年龄相关的外周血氧利用率降低对峰值VO2的限制比CO更强。有必要对针对外周肌肉及其脉管系统的结构和功能进行干预以减轻与年龄相关的（A-V）O2下降的未来研究。
