McCann D J, Molé P A, Caton J R
Department of Physical Education, University of California, Davis 95616, USA.
Med Sci Sports Exerc. 1995 Mar;27(3):378-89.
System linearity was assessed for exercise induced changes in energetics of forearm exercise. 31P-NMR spectroscopy techniques, with 12.5-s serial measurements of [PCr], [Pi], [ATP], and [H+] were employed during exercise and recovery transitions in four untrained men for moderate (1.7 W) and heavy (3.6 W) exercise. Signal averaging was applied and data were analyzed by regression analysis using a first-order exponential model. The time constants for both [PCr] and [Pi] responses to moderate exercise and recovery were not different both within and between nuclei ranging from 32 to 35 s (P > 0.05). The time constants derived from moderate exercise and recovery, when employed to construct predictive equations for heavy exercise and recovery, did not adequately describe [PCr] dynamics. Underestimation of the net hydrolysis of PCr during heavy exercise was associated with increases in [H+] as predicted by the creatine kinase equilibrium reaction (CKeq). Calculation of [ADP] by CKeq revealed steady state [ADP] was achieved during moderate exercise and during recovery for both intensities much earlier than during heavy exercise. We conclude that the metabolic system does not behave as a linear system. Therefore, the time constant and the net change in [PCr].W-1 must themselves be determined by work dependent combinations of other system variables.
对前臂运动能量学中运动诱导的变化进行了系统线性评估。在四名未经训练的男性进行中度（1.7 W）和重度（3.6 W）运动及恢复过渡期间，采用31P-NMR光谱技术，对[PCr]、[Pi]、[ATP]和[H+]进行12.5秒的连续测量。应用信号平均法，并使用一阶指数模型通过回归分析对数据进行分析。[PCr]和[Pi]对中度运动及恢复的响应时间常数在32至35秒的核内和核间均无差异（P>0.05）。从中度运动及恢复得出的时间常数，用于构建重度运动及恢复的预测方程时，不能充分描述[PCr]的动态变化。如肌酸激酶平衡反应（CKeq）所预测，重度运动期间PCr净水解的低估与[H+]的增加有关。通过CKeq计算[ADP]表明，在中度运动期间以及两种强度的恢复过程中，稳态[ADP]的实现比重度运动期间要早得多。我们得出结论，代谢系统并非线性系统。因此，时间常数和[PCr].W-1的净变化本身必须由其他系统变量的工作依赖性组合来确定。
