Human Performance Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, USA.
Acta Physiol (Oxf). 2012 Mar;204(3):362-70. doi: 10.1111/j.1748-1716.2011.02341.x. Epub 2011 Oct 28.
Recent findings have challenged the belief that the cardiac output (CO) and oxygen consumption (VO(2) ) relationship is linear from rest to maximal exercise. The purpose of this study was to determine the CO and stroke volume (SV) response to a range of exercise intensities, 40-100% of VO(2max), during cycling.
Ten well-trained cyclists performed a series of discontinuous exercise bouts to determine the CO and SV vs. VO(2) responses.
The rate of increase in CO, relative to VO(2) , during exercise from 40 to 70% of VO(2max) was 4.4 ± 1.4 L L(-1). During exercise at 70-100% of VO(2max) , the rate of increase in CO was reduced to 2.1 ± 0.9 L L(-1) (P = 0.01). Stroke volume during exercise at 80-100% of VO(2max) was reduced by 7% when compared to exercise at 50-70% of VO(2max) (134 ± 5 vs. 143 ± 5 mL per beat, P = 0.02). Whole body arterial-venous O(2) difference increased significantly as intensity increased.
The observation that the rate of increase in CO is reduced as exercise intensity increases suggests that cardiovascular performance displays signs of compromised function before maximal VO(2) is reached.
最近的研究结果对心输出量（CO）和耗氧量（VO₂）之间的关系从休息到最大运动呈线性的这一观点提出了挑战。本研究的目的是确定在自行车运动中，从 40%到 100%最大摄氧量（VO₂max）的一系列不同运动强度下 CO 和每搏量（SV）的反应。
10 名训练有素的自行车运动员进行了一系列不连续的运动，以确定 CO 和 SV 与 VO₂ 的反应。
在运动过程中，CO 相对于 VO₂的增加率从 40%到 70%的 VO₂max 为 4.4 ± 1.4 L L⁻¹。在 70%到 100%的 VO₂max 运动时，CO 的增加率降低至 2.1 ± 0.9 L L⁻¹（P = 0.01）。与 50%到 70%的 VO₂max 运动时相比，在 80%到 100%的 VO₂max 运动时 SV 降低了 7%（134 ± 5 与 143 ± 5 mL/次，P = 0.02）。全身动静脉氧差随着强度的增加而显著增加。
随着运动强度的增加，CO 增加率的观察结果表明，心血管功能在达到最大 VO₂之前已经出现了功能受损的迹象。
