Hanson P, Nagle F
Cardiol Clin. 1987 May;5(2):157-70.
Isometric exercise produces a characteristic pressor increase in blood pressure which may be important in maintaining perfusion of muscle during sustained contraction. This response is mediated by combined central and peripheral afferent input to medullary cardiovascular centers. In normal individuals the increase in blood pressure is mediated by a rise in cardiac output with little or no change in systemic vascular resistance. However, the pressor response is also maintained during pharmacologic blockade or surgical denervation by increasing systemic vascular resistance. Left ventricular function is normally maintained or improves in normal subjects and cardiac patients with mild impairment of left ventricular contractility. Patients with poor left ventricular function may show deterioration during isometric exercise, although this pattern of response is difficult to predict from resting studies. Recent studies have shown that patients with uncomplicated myocardial infarction can perform submaximum isometric exercise such as carrying weights in the range of 30 to 50 lb without difficulty or adverse responses. In addition, many patients who show ischemic ST depression or angina during dynamic exercise may have a reduced ischemic response during isometric or combined isometric and dynamic exercise. Isometric exercises are frequently encountered in activities of daily living and many occupational tasks. Cardiac patients should be gradually exposed to submaximum isometric training in supervised cardiac rehabilitation programs. Specific job tasks that require isometric or combined isometric and dynamic activities may be evaluated by work simulation studies. This approach to cardiac rehabilitation may facilitate patients who wish to return to a job requiring frequent isometric muscle contraction. Finally, there is a need for additional research on the long-term effects of isometric exercise training on left ventricular hypertrophy and performance. The vigorous training regimens currently utilized by international class and professional athletes should stimulate longitudinal studies of physiologic and pathophysiologic outcomes of intense isometric exercise training programs.
等长运动可使血压出现特征性的升压反应，这在维持肌肉持续收缩期间的灌注方面可能很重要。这种反应是由中枢和外周传入神经向延髓心血管中枢的联合输入介导的。在正常个体中，血压升高是由心输出量增加介导的，全身血管阻力几乎没有变化或没有变化。然而，在药物阻断或手术去神经支配期间，通过增加全身血管阻力也能维持升压反应。在正常受试者以及左心室收缩功能轻度受损的心脏病患者中，左心室功能通常得以维持或改善。左心室功能较差的患者在等长运动期间可能会出现病情恶化，尽管这种反应模式很难从静息研究中预测出来。最近的研究表明，无并发症的心肌梗死患者可以轻松进行次最大强度的等长运动，如搬运30至50磅的重物，且不会出现不良反应。此外，许多在动态运动期间出现缺血性ST段压低或心绞痛的患者，在等长运动或等长与动态联合运动期间可能会有降低的缺血反应。等长运动在日常生活活动和许多职业任务中经常出现。心脏病患者应在有监督的心脏康复计划中逐渐接受次最大强度的等长训练。需要进行等长运动训练对左心室肥厚和功能影响的长期效应的进一步研究。国际级和职业运动员目前采用的高强度训练方案应促使人们对高强度等长运动训练计划的生理和病理生理结果进行纵向研究。
