Davis H A, Bassett J, Hughes P, Gass G C
Eur J Appl Physiol Occup Physiol. 1983;50(3):383-92. doi: 10.1007/BF00423244.
Venous lactate concentration and ventilatory responses to progressively increased work rates were studied in 16 men who performed an incremental exercise test to exhaustion on an electrically braked cycle ergometer. In this test the characteristic curvilinear increase in venous lactate concentrations was observed. In addition to the anaerobic threshold (AT), a second breakpoint was observed and named the lactate turnpoint (LTP). Eight of the 16 subjects performed a second incremental exercise test initiated during lactic acidosis. In this test the direction of change in venous lactate concentrations was different. The work rate at which lactate concentrations again increased, after a steady decline (previously described as the AT2), was similar to the work rate established for the LTP in the first test. In the second test removal of lactate was demonstrated at work rates exceeding the AT. Although the lactate response to the two tests was different the pattern of change was similar, with the two breakpoints occurring at the same work rates. Collectively these results lend a measure of support to the hypothesis of a positive relationship between the AT, LTP, and a pattern of recruitment of motor units with different enzyme profiles. Both the AT and LTP were predictable from the ventilatory response to incremental exercise.
对16名男性进行了研究，他们在电动刹车的自行车测力计上进行递增运动测试直至精疲力竭，期间测定静脉血乳酸浓度以及对逐渐增加的工作负荷的通气反应。在该测试中，观察到静脉血乳酸浓度呈特征性的曲线上升。除了无氧阈（AT）外，还观察到第二个转折点，并将其命名为乳酸转折点（LTP）。16名受试者中有8人在乳酸酸中毒期间进行了第二次递增运动测试。在该测试中，静脉血乳酸浓度的变化方向不同。乳酸浓度在稳定下降后再次上升时的工作负荷（之前称为AT2），与第一次测试中为LTP确定的工作负荷相似。在第二次测试中，在超过AT的工作负荷下证明了乳酸的清除。尽管对两次测试的乳酸反应不同，但变化模式相似，两个转折点出现在相同的工作负荷下。总体而言，这些结果为AT、LTP以及具有不同酶谱的运动单位募集模式之间存在正相关的假设提供了一定程度的支持。AT和LTP均可根据递增运动的通气反应预测。
