Effects of endurance training on reduction of plasma glucose during high intensity constant and incremental speed tests in Wistar rats

The aim of this research was to investigate the effects of endurance training on reduction of plasma glucose during high intensity constant and incremental speed tests in Wistar rats. We hypothesized that plasma glucose might be decreased in the exercised group during heavy (more intense) exercise. Twenty-four 10-week-old male Wistar rats were randomly assigned to sedentary and exercised groups. The prescription of endurance exercise training intensity was determined as 60% of the maximum intensity reached at the incremental speed test. The animals were trained by running on a motorized treadmill, five days/week for a total period of 67 weeks. Plasma glucose during the constant speed test in the exercised group at 20 m/min was reduced at the 14th, 21st and 28th min compared to the sedentary group, as well at 25 m/min at the 21st and 28th min. Plasma glucose during the incremental speed test was decreased in the exercised group at the moment of exhaustion (48th min) compared to the sedentary group (27th min). Endurance training positively modulates the mitochondrial activity and capacity of substrate oxidation in muscle and liver. Thus, in contrast to other studies on high load of exercise, the effects of endurance training on the decrease of plasma glucose during constant and incremental speed tests was significantly higher in exercised than in sedentary rats and associated with improved muscle and hepatic oxidative capacity, constituting an important non-pharmacological intervention tool for the prevention of insulin resistance, including type 2 diabetes mellitus.

本研究旨在探讨耐力训练对Wistar大鼠（Wistar rats）在高强度恒定速度与递增速度运动测试期间血浆葡萄糖（plasma glucose）水平降低的影响。本研究提出如下假设：在大强度（更高强度）运动过程中，运动组大鼠的血浆葡萄糖水平可能会出现下降。将24只10周龄的雄性Wistar大鼠随机均分为久坐组与运动组。耐力运动训练强度的确定标准为：以递增速度测试中大鼠达到的最大强度的60%作为训练强度。实验动物通过电动跑台（motorized treadmill）进行训练，每周训练5天，总训练周期为67周。相较于久坐组，运动组在20m/min的恒定速度测试中，第14、21及28分钟时的血浆葡萄糖水平显著降低；在25m/min的测试中，第21与28分钟时亦存在该降低趋势。在递增速度测试中，相较于久坐组（大鼠力竭时间为第27分钟），运动组在力竭时刻（第48分钟）的血浆葡萄糖水平显著降低。耐力训练可正向调节肌肉与肝脏的线粒体活性及底物氧化能力。与其他针对高负荷运动的研究有所不同，本研究结果显示，在恒定速度与递增速度测试期间，耐力训练对血浆葡萄糖水平降低的促进作用在运动组大鼠中显著高于久坐组，且该效应与肌肉及肝脏氧化能力的改善密切相关，可作为预防胰岛素抵抗（insulin resistance）及2型糖尿病（type 2 diabetes mellitus）的重要非药物干预手段。