Kjaer M, Pott F, Mohr T, Linkis P, Tornøe P, Secher N H
Sports Medicine Research Unit, Department of Rheumatology H, Bispebjerg Hospital, DK-2400 Copenhagen NV.
J Appl Physiol (1985). 1999 Mar;86(3):806-11. doi: 10.1152/jappl.1999.86.3.806.
Feed-forward and feedback mechanisms are both important for control of the heart rate response to muscular exercise, but their origin and relative importance remain inadequately understood. To evaluate whether humoral mechanisms are of importance, the heart rate response to electrically induced cycling was studied in participants with spinal cord injury (SCI) and compared with that elicited during volitional cycling in able-bodied persons (C). During voluntary exercise at an oxygen uptake of approximately 1 l/min, heart rate increased from 66 +/- 4 to 86 +/- 4 (SE) beats/min in seven C, and during electrically induced exercise at a similar oxygen uptake in SCI it increased from 73 +/- 3 to 110 +/- 8 beats/min. In contrast, blood pressure increased only in C (from 88 +/- 3 to 99 +/- 4 mmHg), confirming that, during exercise, blood pressure control is dominated by peripheral neural feedback mechanisms. With vascular occlusion of the legs, the exercise-induced increase in heart rate was reduced or even eliminated in the electrically stimulated SCI. For C, heart rate tended to be lower than during exercise with free circulation to the legs. Release of the cuff elevated heart rate only in SCI. These data suggest that humoral feedback is of importance for the heart rate response to exercise and especially so when influence from the central nervous system and peripheral neural feedback from the working muscles are impaired or eliminated during electrically induced exercise in individuals with SCI.
前馈和反馈机制对于控制运动时的心率反应均很重要，但其起源和相对重要性仍未得到充分理解。为评估体液机制是否重要，对脊髓损伤（SCI）参与者进行电刺激诱发的骑行时的心率反应进行了研究，并与健全人（C组）自主骑行时的心率反应进行比较。在摄氧量约为1升/分钟的自愿运动期间，7名C组参与者的心率从66±4次/分钟增加到86±4次/分钟，而在SCI患者中，在类似摄氧量的电刺激运动期间，心率从73±3次/分钟增加到110±8次/分钟。相比之下，血压仅在C组中升高（从88±3毫米汞柱升至99±4毫米汞柱），这证实了在运动期间，血压控制主要由外周神经反馈机制主导。在腿部血管闭塞的情况下，电刺激的SCI患者运动诱发的心率增加减少甚至消除。对于C组，心率往往低于腿部自由循环运动时的心率。松开袖带仅使SCI患者的心率升高。这些数据表明，体液反馈对于运动时的心率反应很重要；尤其是在SCI患者进行电刺激运动时，中枢神经系统的影响以及来自工作肌肉的外周神经反馈受损或消除的情况下。
