Paterson D H, Shephard R J, Cunningham D, Jones N L, Andrew G
J Appl Physiol Respir Environ Exerc Physiol. 1979 Sep;47(3):482-9. doi: 10.1152/jappl.1979.47.3.482.
Three to twelve (7.1 +/- 3.2) months after myocardial infarction, subjects under 54 (45.0 +/- 4.7) yr were assigned randomly to high-intensity (HIE, n = 37) or low-intensity (LIE, n = 42) exercise programs. Cardiac outputs (Q) during graded bicycle ergometer exercise were measured by a CO2-rebreathing method on entry and after 6 and 12 mo of training. The initial exercise Q was low in relation to work load, due to a low stroke volume (SV). Over the year of training, the predicted maximal O2 intake of the HIE group increased significantly (from 26.0 to 30.3 ml.kg-1.min-1), while that of the LIE group showed no significant alteration. During the first 6 mo, the heart rate of the HIE group was significantly reduced at each work level. There was an associated widening of arteriovenous oxygen difference, but SV was unchanged. These findings were attributed to extracardiac factors, including a redistribution of blood flow, biochemical changes in the trained muscle, and a secondary reduction of sympathetic drive. Over the second 6 mo, the SV of the HIE group increased 10%; this may reflect an increase of intrinsic myocardial contractility that develops if high-intensity training is sustained. The LIE group showed no major changes of cardiovascular function over the year of observation.
心肌梗死后3至12（7.1±3.2）个月，将54（45.0±4.7）岁以下的受试者随机分配至高强度运动组（HIE，n = 37）或低强度运动组（LIE，n = 42）。在训练开始时以及训练6个月和12个月后，采用二氧化碳重呼吸法测量分级运动踏车运动期间的心输出量（Q）。由于每搏输出量（SV）较低，初始运动时的心输出量与工作量相比很低。在一年的训练中，HIE组预测的最大摄氧量显著增加（从26.0增至30.3 ml·kg-1·min-1），而LIE组则无显著变化。在最初的6个月内，HIE组在每个工作水平时的心率均显著降低。同时动静脉氧差增大，但每搏输出量不变。这些发现归因于心外因素，包括血流重新分布、训练肌肉中的生化变化以及交感神经驱动的继发性降低。在第二个6个月期间，HIE组的每搏输出量增加了10%；这可能反映了如果持续进行高强度训练，心肌内在收缩力会增加。在一年的观察期内，LIE组的心血管功能无重大变化。
