Harms C A
Department of Kinesiology, Kansas State University, Manhattan 66506, USA.
Med Sci Sports Exerc. 2000 Jan;32(1):94-9. doi: 10.1097/00005768-200001000-00015.
Cardiac output is directed primarily to skeletal muscle during exercise. Recent investigations have examined how different groups of skeletal muscle compete for the cardiac output during exercise. To date, there is a lack of consistent findings on a blood flow steal effect of arm versus leg exercise, although the majority of data suggest that leg blood flow is not compromised when arm exercise is added to leg exercise. A recent set of experiments have demonstrated that respiratory muscles compete favorably for blood flow with the legs during maximal exercise. Decreased work of breathing leads to: 1) a decrease in cardiac output, due primarily to reduced stroke volume; and 2) increased leg blood flow and leg vascular conductance. An increased work of breathing leads to the converse. Exercise performance may also be affected by the work of breathing during heavy exercise due to redistribution of blood flow between the chest wall and the locomotor muscles. It appears that in contrast to arm exercise, respiratory muscles demand a significant portion of the cardiac output during maximal exercise, and the work of breathing normally experienced during heavy exercise compromises leg blood flow.
运动期间心输出量主要流向骨骼肌。最近的研究探讨了不同组别的骨骼肌在运动过程中如何竞争心输出量。迄今为止，关于手臂运动与腿部运动的血流窃取效应，尚未有一致的研究结果，尽管大多数数据表明，在腿部运动基础上增加手臂运动时，腿部血流量不受影响。最近的一组实验表明，在最大运动时，呼吸肌与腿部竞争血流量占优。呼吸功降低会导致：1）心输出量减少，主要原因是每搏输出量降低；2）腿部血流量和腿部血管传导性增加。呼吸功增加则会导致相反的情况。在剧烈运动时，呼吸功也可能会影响运动表现，因为胸壁和运动肌肉之间会发生血流重新分配。与手臂运动不同，在最大运动时，呼吸肌需要相当一部分心输出量，而剧烈运动时通常的呼吸功会影响腿部血流量。
