4.3 Article

Age-related prolongation of phase I of V over dotO2 on-kinetics in healthy humans

出版社

AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpregu.00739.2009

关键词

aging; oxygen consumption; on-response; moderate-intensity exercise

向作者/读者索取更多资源

Mezzani A, Grassi B, Giordano A, Corra U, Colombo S, Giannuzzi P. Age-related prolongation of phase I of V over dotO(2) on-kinetics in healthy humans. Am J Physiol Regul Integr Comp Physiol 299: R968-R976, 2010. First published July 7, 2010; doi: 10.1152/ajpregu.00739.2009.-Data are lacking regarding age-related modifications of phase I (PhI) of pulmonary V over dotO(2) on-kinetics during moderate-intensity exercise. We studied three groups (aged 20-30, 40-50, and 60-70 years) of 10 normal subjects, who underwent one incremental and four below-gas exchange threshold constant-power cardiopulmonary exercise tests. Data from constant-power tests were time-aligned and averaged, and the PhI-phase II transition (PhI-IItr) determined when a sharp decrease from baseline of respiratory exchange ratio occurred. The V over dotO(2) phase II time constant (tau) was obtained by an exponential fitting starting 1) from PhI-IItr (experimental fitting strategy) and 2) after 20 s from exercise onset (fixed-duration fitting strategy). Assuming estimated arterial-venous O-2 concentration difference not to change with respect to resting value, cardiac output (CO) values at rest and PhI-IItr were obtained according to Fick's principle. Average pulmonary flow acceleration (AFA) during PhI was calculated as the ratio between CO increase during PhI and PhI duration. PhI duration was related to age (r = 0.74, P < 0.0001), increasing from 21 +/- 3 s to 27 +/- 3 s to 32 +/- 4 s in the 20-30, 40-50, and 60-70 age groups, respectively, and to AFA (r = -0.60, P < 0.001), but not to CO increase during PhI. With respect to the experimental fitting strategy, the fixed-duration strategy overestimated V over dotO(2) phase II tau the more the higher the subject's age, with a lower goodness of fit in the 60-70 group (SE 0.035 vs. 0.056, P < 0.01). In conclusion, PhI duration is related to age in healthy male humans and is linked to CO acceleration-rather than to increase-during PhI. A significant overestimation of phase II tau thus may occur in healthy elderly subjects and patients with a pathologically induced longer PhI duration when fitting data where the PhI-PhIItr was not experimentally determined but assumed to be a set value (i.e., 20 s).

作者

我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。

评论

主要评分

4.3
评分不足

次要评分

新颖性
-
重要性
-
科学严谨性
-
评价这篇论文

推荐

暂无数据
暂无数据