Dressendorfer R H, Smith J L, Amsterdam E A, Mason D T
Am Heart J. 1982 Mar;103(3):358-62. doi: 10.1016/0002-8703(82)90274-5.
To assess the effects of walk training on external work efficiency and the determinants of myocardial oxygen demand (MVO2), we measured total somatic oxygen consumption (VO2), heart rate (HR), and systolic blood pressure (SBP) in eight male coronary (CAD) patients during submaximal treadmill walking before and after at least 14 weeks of prescribed exercise. Each patient was tested before and after training at the individually determined horizontal treadmill speed that induced ischemic ST segment depression in the pretraining test. Although maximal oxygen uptake (VO2 max) did not increase significantly with training, submaximal exercise HR and the product of HR and SBP were significantly (p less than 0.05) reduced by 10% (120 leads to 108/min) and 16% (185 X 10(2) leads to 156 X 10(2)), respectively, and none of the patients had ischemic ECG changes after training. The reductions in the cardiac response to exercise were due primarily to a 10% decrease (18.9 leads to 17.1 ml/kg/min, p less than 0.05) in somatic oxygen requirements (VO2), indicating that the patients became more efficient walkers and reduced their MVO2 in proportion to the decreased total VO2. Thus, enhancement of external work efficiency, an extracardiac factor, can lessen myocardial energy costs (MVO2) and thereby raise the exercise threshold for cardiac ischemia in CAD patients even when aerobic capacity (VO2 max) is not increased.
为评估步行训练对外部工作效率以及心肌需氧量（MVO2）决定因素的影响，我们在8名男性冠心病（CAD）患者进行至少14周规定运动前后，于次极量跑步机步行期间测量了总体氧耗（VO2）、心率（HR）和收缩压（SBP）。每位患者在训练前后，均在个体确定的水平跑步机速度下进行测试，该速度在训练前测试中会诱发缺血性ST段压低。尽管最大摄氧量（VO2 max）并未随训练显著增加，但次极量运动时的心率以及心率与收缩压的乘积分别显著降低（p<0.05），降低了10%（从120次/分钟降至108次/分钟）和16%（从185×10²降至156×10²），且训练后无患者出现缺血性心电图改变。运动时心脏反应的降低主要是由于总体氧需求（VO2）下降了10%（从18.9降至17.1毫升/千克/分钟，p<0.05），这表明患者步行效率提高，且MVO2随总VO2的降低成比例减少。因此，作为心脏外因素的外部工作效率的提高，可降低心肌能量消耗（MVO2），从而提高CAD患者心脏缺血的运动阈值，即便有氧能力（VO2 max）并未增加。
