Saito M, Tsukanaka A, Yanagihara D, Mano T
Laboratory of Applied Physiology, Toyota Technological Institute, Nagoya, Japan.
J Appl Physiol (1985). 1993 Aug;75(2):663-7. doi: 10.1152/jappl.1993.75.2.663.
The aim of this study was to clarify the relationship between sympathetic outflow to skeletal muscle and oxygen uptake during dynamic exercise. Muscle sympathetic nerve activity (MSNA) was recorded from the right median nerve microneurographically in eight healthy volunteers during leg cycling at four different intensities in a seated position for a 16-min bout. Work loads selected were 20, 40, 60, and 75% of maximal oxygen uptake (VO2max). Heart rate and blood pressure were measured during each exercise test. MSNA burst frequency was suppressed by 28% during cycling at 20% VO2max (23 vs. 33 bursts/min for control). Thereafter, it increased in a linear fashion with increasing work rate, with a significantly higher burst frequency during 60% VO2max than the control value. Both heart rate and mean blood pressure rose significantly during 20% VO2max from the control value and increased linearly with increased exercise intensity. During light exercise, MSNA was suppressed by arterial and cardiopulmonary baroreceptors as a result of the hemodynamic changes associated with leg muscle pumping. The baroreflex inhibition may overcome the muscle metaboreflex excitation to induce MSNA suppression during light exercise. These results suggest that during light exercise MSNA is inhibited, perhaps due to loading of the cardiopulmonary and arterial baroreflexes, and that during heavier exercise the increase in MSNA occurs as muscle metaboreflexes are activated.
本研究的目的是阐明动态运动期间骨骼肌交感神经输出与摄氧量之间的关系。在8名健康志愿者坐位进行16分钟腿部骑行运动时，以四种不同强度通过微神经电图从右侧正中神经记录肌肉交感神经活动（MSNA）。所选的工作负荷分别为最大摄氧量（VO2max）的20%、40%、60%和75%。在每次运动测试期间测量心率和血压。在以20%VO2max进行骑行时，MSNA爆发频率降低了28%（对照时为33次/分钟，此时为23次/分钟）。此后，随着工作率增加，其呈线性增加，在60%VO2max时的爆发频率显著高于对照值。在20%VO2max时，心率和平均血压均较对照值显著升高，并随着运动强度增加而线性增加。在轻度运动期间，由于与腿部肌肉泵血相关的血流动力学变化，MSNA受到动脉和心肺压力感受器的抑制。压力反射抑制可能会克服肌肉代谢反射兴奋，从而在轻度运动期间诱导MSNA抑制。这些结果表明，在轻度运动期间MSNA受到抑制，可能是由于心肺和动脉压力反射的负荷，而在较重运动期间，随着肌肉代谢反射被激活，MSNA增加。
