von Duvillard S P, LeMura L M, Bacharach D W, Di Vico P
Department of Clinical Sciences, University of Massachusetts, Lowell.
J Manipulative Physiol Ther. 1993 Jun;16(5):312-8.
The purpose of this investigation was the determination of the lactate threshold (LT) by selected respiratory gas exchange measures and venous blood lactate levels during incremental load work on a mechanically braked cycle ergometer.
Repeated measures design.
Human Performance Laboratory.
Eight healthy trained soccer players (mean age 21.9 +/- 3.0 yr, mean VO2max = 59.2 +/- 3.6 ml.kg.min-1).
Subjects conducted two incremental load work tests. Incremental load work was increased by 1 kilopond (kp) every third minute at 60 rpm until voluntary exhaustion. Blood samples from a forearm vein were collected during the second trial (T2) only and analyzed for lactic acid [LA-].
One-way analysis of variance (ANOVA) with repeated measures indicated no statistically significant difference between the two tests for maximal oxygen uptake (VO2max), maximal carbon dioxide production (VCO2max), maximal heart rate (HRmax), maximal pulmonary ventilation (VEBTPSmax) and lowest ventilatory equivalent of oxygen (VE/VO2), respectively; however, there was a significant difference among the oxygen uptake (VO2) values at the LT for the four determination methods. In our subjects, the measured (mean +/- SD) VE/VO2 in relation to VO2 for the first trial (T1) of 22.9 +/- 1.9 occurred at VO2 of 1.27 +/- 0.8 l.min-1. The lowest VE/VO2 and the onset of [LA-] accumulation calculated from individual exponential equations relating VE to VO2 yielded VO2 values of 1.77 +/- 0.18 and 1.74 +/- 0.25 l.min-1 for the T2. Utilizing natural log for lactate ln [LA-] to natural log for ln (VO2) equations, the LT for T2 occurred at VO2 of 1.30 +/- 0.70 l.min-1.
LT was best predicted by the measured lowest VE/VO2 and the plot of the ln [LA-] to ln VO2 relationship. The methods used in this study provide a valid estimate of the LT and support the use of measured lowest VE/VO2 as an indirect measure of the LT.
本研究旨在通过在机械制动的自行车测力计上进行递增负荷运动时，采用选定的呼吸气体交换测量方法和静脉血乳酸水平来测定乳酸阈值（LT）。
重复测量设计。
人体运动实验室。
八名健康的受过训练的足球运动员（平均年龄21.9±3.0岁，平均最大摄氧量=59.2±3.6毫升·千克·分钟⁻¹）。
受试者进行了两次递增负荷运动测试。以每分钟60转的速度，每三分钟递增1千克力（kp），直至自愿疲劳。仅在第二次试验（T2）期间从前臂静脉采集血样，并分析乳酸[LA⁻]。
重复测量的单因素方差分析（ANOVA）表明，两次测试在最大摄氧量（VO2max）、最大二氧化碳产生量（VCO2max）、最大心率（HRmax）、最大肺通气量（VEBTPSmax）和最低氧通气当量（VE/VO2）方面无统计学显著差异；然而，四种测定方法在乳酸阈值时的摄氧量（VO2）值存在显著差异。在我们的受试者中，第一次试验（T1）中与VO2相关的测量（平均值±标准差）VE/VO2为22.9±1.9，此时VO2为1.27±0.8升·分钟⁻¹。根据将VE与VO2相关的个体指数方程计算得出的最低VE/VO2和[LA⁻]积累起始点，T2时的VO2值分别为1.77±0.18和1.74±0.25升·分钟⁻¹。利用乳酸的自然对数ln[LA⁻]与ln（VO2）的方程，T2的乳酸阈值出现在VO2为1.30±0.70升·分钟⁻¹时。
乳酸阈值最好通过测量的最低VE/VO2以及ln[LA⁻]与ln VO2关系图来预测。本研究中使用的方法提供了对乳酸阈值的有效估计，并支持将测量的最低VE/VO2用作乳酸阈值的间接测量方法。
