Nakagawa Y
Second Department of Pathology, Hokkaido University School of Medicine, Sapporo, Japan.
Hokkaido Igaku Zasshi. 1998 Jul;73(4):379-88.
This study sets out 31P-nuclear magnetic resonance (NMR) determinations of the muscle energy metabolism during anaerobic isometric exercise, histochemical analysis of the muscle biopsies, and the muscle characteristics. Subjects were six healthy males (controls, CON), five sprint-trained athletes (SPR), and four endurance-trained athletes (END). The three groups had similar fiber distribution and the percentages of fiber area in tibialis anterior muscles which were predominantly slow-twitch fiber. The mean of capillary numbers in END was higher than those in CON and SPR. The peak torque per unit muscle volume of the dorsiflexors was higher in SPR compared to those in CON and END. The subjects performed dorsiflexion at work load of 50% of maximal exercise intensity for 50 seconds with cuff-arrested circulation for estimation of the anaerobic metabolism. The ATP turnover in CON and SPR increased rapidly at 20 sec (p < 0.05) compared to the initial value and increased progressively afterwards. However, that in END remained relatively constant with time course. Mechanical efficiency (ME) in each group decreased gradually during the time course. A significant decrease was found in CON at 40 sec compared to that at 10 sec. ME in SPR decreased abruptly at 20 sec (p < 0.05). However, ME in END remained relatively stable during exercise as well as ATP turnover. The highest rates of PCr were observed in CON and END at 10 sec and in SPR at 20 sec; afterwards these decreased progressively. A significant decrease was found only in CON at 50 sec compared to that at 10 sec (p < 0.05). The highest rates of glycolysis were observed in all groups at 50 sec compared to those at 10 sec (p < 0.05), which indicated that these increased gradually with time course. The percentages of PCr depletion in three groups were greater than those of glycolysis until 30 sec. These results suggest that the anaerobic energy metabolism and muscle characteristics of the dorsiflexors adapt to a specific type of training used in athletes excepting the fiber types.
本研究开展了31P-核磁共振（NMR）测定，以研究无氧等长运动期间的肌肉能量代谢，对肌肉活检组织进行了组织化学分析，并分析了肌肉特征。受试者包括6名健康男性（对照组，CON）、5名短跑训练运动员（SPR）和4名耐力训练运动员（END）。三组的纤维分布相似，胫骨前肌中纤维面积的百分比主要为慢肌纤维。END组的毛细血管平均数高于CON组和SPR组。与CON组和END组相比，SPR组背屈肌每单位肌肉体积的峰值扭矩更高。受试者在最大运动强度的50%工作负荷下进行50秒的背屈，通过袖带阻断循环来评估无氧代谢。与初始值相比，CON组和SPR组的ATP周转率在20秒时迅速增加（p<0.05），随后逐渐增加。然而，END组的ATP周转率随时间相对保持恒定。每组的机械效率（ME）在运动过程中逐渐降低。与10秒时相比，CON组在40秒时显著降低。SPR组的ME在20秒时突然降低（p<0.05）。然而，END组的ME在运动期间以及ATP周转率方面相对稳定。CON组和END组在10秒时以及SPR组在20秒时观察到磷酸肌酸（PCr）的最高速率；随后这些速率逐渐降低。与10秒时相比，仅CON组在50秒时显著降低（p<0.05）。与10秒时相比，所有组在50秒时观察到糖酵解的最高速率（p<0.05），这表明糖酵解速率随时间逐渐增加。直到30秒，三组中PCr消耗的百分比大于糖酵解的百分比。这些结果表明，除了纤维类型外，背屈肌的无氧能量代谢和肌肉特征适应运动员所采用的特定训练类型。
