Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan.
Graduate School of Medicine, Nagoya University, Nagoya, Japan.
Exp Physiol. 2022 Aug;107(8):825-833. doi: 10.1113/EP090497. Epub 2022 Jul 4.
What is the central question of this study? Sympathetic vasomotor outflow is reduced during low-intensity dynamic leg exercise in younger individuals: does ageing influence the sympathoinhibitory effect during low-intensity leg cycling? What is the main finding and its importance? Muscle sympathetic nerve activity during low-intensity cycling decreased in older males, as seen in young males. It is possible that cardiopulmonary baroreflex-mediated inhibition of sympathetic vasomotor outflow during dynamic leg exercise is preserved in healthy older males.
Muscle sympathetic nerve activity (MSNA) is reduced during low-intensity dynamic leg exercise in young males. It is suggested that this inhibition is mediated by loading of the cardiopulmonary baroreceptors. The purpose of this study was to clarify the impact of age on MSNA during dynamic leg exercise. Nine younger males (YM, mean ± SD, 20 ± 1 years) and nine older males (OM, 72 ± 3 years) completed the study. The subjects performed two 4-min cycling exercises at 10% of their heart rate reserve using a cycle ergometer in a semirecumbent position (MSNA and estimated central venous pressure (eCVP) trials). MSNA was recorded via microneurography of the left radial nerve. The CVP was estimated based on peripheral venous pressure, which was monitored using a cannula in the right large antecubital vein. The magnitude of the increase in mean arterial blood pressure during leg cycling was larger in OM (+9.3 ± 5.5 mmHg) compared with YM (+2.8 ± 4.7 mmHg). MSNA burst frequency was decreased during cycling in both YM (-8.1 ± 3.8 bursts/min) and OM (-10.6 ± 3.3 bursts/min), but no significant difference was found between the two groups. The eCVP increased during exercise in both groups, and there was no difference in the changes in eCVP between YM (+1.1 ± 0.4 mmHg) and OM (+1.2 ± 0.7 mmHg). These data indicate that inhibition of sympathetic vasomotor outflow during low-intensity cycling appears in OM as seen in YM. It is possible that the muscle pump-induced loading of the cardiopulmonary baroreflex is preserved during cycling in healthy older males.
本研究的核心问题是什么？在年轻个体进行低强度动力性腿部运动时，交感血管运动传出减少：衰老是否会影响低强度腿部踏车运动期间的交感抑制作用？主要发现及其重要性是什么？与年轻男性一样，老年男性在进行低强度踏车运动时，肌肉交感神经活动（MSNA）降低。在健康的老年男性中，可能存在心肺压力感受器介导的动态腿部运动时交感血管运动传出抑制。
在年轻男性进行低强度动力性腿部运动时，MSNA 会减少。这种抑制作用被认为是通过心肺压力感受器的负荷介导的。本研究旨在阐明年龄对动态腿部运动时 MSNA 的影响。9 名年轻男性（YM，平均±标准差，20±1 岁）和 9 名老年男性（OM，72±3 岁）完成了这项研究。受试者在半卧位使用自行车测力计进行两次 4 分钟的 10%心率储备的踏车运动（MSNA 和估计中心静脉压（eCVP）试验）。MSNA 通过左侧桡神经的微神经记录。CVP 是基于外周静脉压估计的，外周静脉压是通过右前臂大静脉的导管监测的。与 YM（+2.8±4.7mmHg）相比，OM（+9.3±5.5mmHg）在腿部踏车时平均动脉血压的升高幅度更大。在 YM（-8.1±3.8 次/分钟）和 OM（-10.6±3.3 次/分钟）中，MSNA 爆发频率在踏车期间均降低，但两组之间无显著差异。在两组中，eCVP 在运动期间均增加，YM（+1.1±0.4mmHg）和 OM（+1.2±0.7mmHg）之间的 eCVP 变化无差异。这些数据表明，在 OM 中观察到的低强度踏车运动期间交感血管运动传出的抑制作用也出现在 YM 中。在健康的老年男性中，可能存在肌肉泵诱导的心肺压力感受器负荷在踏车运动期间得以保留。
