一般来说，一些用于运动状况下心输出量 (Q)测定的技术能精确、可取地测定亚极量运动状况下的 Q，而在极量运动过程中的运用则受到限制。过去通常用的非损伤性的方法中只有 C2H2(乙炔 )重呼吸法适用于极量运动中，它完全无损伤性、简便易行、切实有效。近年来，运动状况下叠的测定的新方法已经发展，且在运动生理学和运动心脏学上已逐渐受到育踩。除阻抗心动描记器外，这些方法中的大部分理论上可以精确、可靠地田定 Q。然而，它们在极量运动中的使用费用和技术限制阻碍了它们取代常规方法。多普勒超声波技术和修正过的 C2H2法有望用于极量运动状况下 Q的预定，随着这些技术的进一步发展，它们在运动生理学和运动心脏病学方面的应用将会更普遍。%There are several techniques available to measure Q during exercise conditions． These procedures generally provide accurate and reliable determination of Q during Submaxtmal exercise， but may be limited during maximal exercise conditions． In the mostCommenly used noninvasine measures， only the acetylene(C2H2) rebreathe methods meetsa11 of the criteria of being noninvasive， easy to use， reliable and valid for use during maximalexercise． New methodlogies have recently been developed to measure Q during exerciseConditions， these methods have increasingly gained favour in exercise physiology and sportcardiology settings． The majority of these measures with the exception of impedanceCardiography， provide reasonably accurate and reliable determination of Q． However， theCost of usage and technologica1 limitations during maximel exercise have prevented thesetechniques from replacing the conventional measures of Q during exercise conditions． Doppler echocardiography alld the modified C2H2 methods hold promise for the assessment ofQ druing maximal exercise． With further advances in these technologies, their use in exercisephysioiogy and sport cardiology settings may become more common．
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