Schneider D A, McLellan T M, Gass G C
Exercise Science Research Laboratory, School of Physiotherapy and Exercise Science, Griffith University, Gold Coast, Queensland, Australia.
Med Sci Sports Exerc. 2000 Mar;32(3):608-13. doi: 10.1097/00005768-200003000-00009.
The present study was conducted to examine the pattern of plasma catecholamine and blood lactate responses to incremental arm and leg exercise. Seven untrained male subjects performed two incremental exercise tests on separate days in random order. One test consisted of 1-arm cranking (5W x 2 min(-1)), whereas the other exercise test was 2-leg cycling (20-25W x 2 min(-1)). Blood samples were obtained from the nonexercising arm during 1-arm cranking and from the same arm and vein during 2-leg cycling. Thresholds for blood lactate (T(La)), epinephrine (T(Epi)) and norepinephrine (T(NE)) were determined for each subject under both exercise conditions and defined as breakpoints when plotted as a function of power output.
When the two modes of exercise were compared, T(La), T(Epi), and T(NE) were all significantly lower for 1-arm cranking than for 2-leg cycling (P < 0.01). During 1-arm cranking, T(La) (0.96 +/- 0.10 L x min(-1)), T(Epi) (1.02 +/- 0.07 L x min(-1)), and T(NE) (1.07 +/- 0.09 L x min(-1)) occurred simultaneously. During 2-leg cycling, T(La) (1.77 +/- 0.20 L x min(-1)), T(Epi) (1.74 +/- 0.17 L x min(-1)), and T(NE) (1.98 +/- 0.17 L x min(-1)) occurred at similar levels of VO2 and were not significantly different. The correlation observed between the VO2 measured at the T(La) and T(Epi) was 0.917 for arm and 0.929 for leg exercise (P < 0.001). The epinephrine concentration ([Epi]) obtained at the T(La) was not significantly different for arm (0.144 ng x mL(-1)) and leg (0.152 ng x mL(-1)) exercise.
The breakpoint in plasma [Epi] shifted in an identical manner and occurred simultaneously with that of T(La) regardless of the mode of exercise (arm or leg). The Epi concentrations observed at the T(La) agree with those previously reported to produce a rise in blood lactate during Epi infusion at rest. These results support the hypothesis that a rise in plasma [Epi] may contribute to the breakpoint in blood lactate that occurs during incremental exercise.
本研究旨在检测递增式手臂和腿部运动时血浆儿茶酚胺和血乳酸的反应模式。七名未经训练的男性受试者在不同日期以随机顺序进行了两项递增运动测试。一项测试为单臂曲柄运动（5瓦×2分钟⁻¹），另一项运动测试为双腿骑行（20 - 25瓦×2分钟⁻¹）。在单臂曲柄运动期间，从不运动的手臂采集血样；在双腿骑行期间，从同一只手臂和静脉采集血样。在两种运动条件下，为每个受试者测定血乳酸（T(La)）、肾上腺素（T(Epi)）和去甲肾上腺素（T(NE)）的阈值，并将其定义为作为功率输出函数绘制时的断点。
比较两种运动模式时，单臂曲柄运动的T(La)、T(Epi)和T(NE)均显著低于双腿骑行（P < 0.01）。在单臂曲柄运动期间，T(La)（0.96 ± 0.10升×分钟⁻¹）、T(Epi)（1.02 ± 0.07升×分钟⁻¹）和T(NE)（1.07 ± 0.09升×分钟⁻¹）同时出现。在双腿骑行期间，T(La)（1.77 ± 0.20升×分钟⁻¹）、T(Epi)（1.74 ± 0.17升×分钟⁻¹）和T(NE)（1.98 ± 0.17升×分钟⁻¹）在相似的VO₂水平出现，且差异不显著。在T(La)和T(Epi)测得的VO₂之间观察到的相关性，手臂运动为0.917，腿部运动为0.929（P < 0.001）。在T(La)时获得的手臂运动（0.144纳克×毫升⁻¹）和腿部运动（0.152纳克×毫升⁻¹）的肾上腺素浓度（[Epi]）差异不显著。
无论运动模式是手臂还是腿部，血浆[Epi]的断点以相同方式移动，并与T(La)的断点同时出现。在T(La)时观察到的Epi浓度与先前报道的在静息状态下Epi输注期间导致血乳酸升高的浓度一致。这些结果支持了以下假设，即血浆[Epi]的升高可能导致递增运动期间血乳酸的断点。
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