Consumption of a high-fat diet (HFD) significantly increases exercise endurance performance during treadmill running. However, whether HFD consumption increases endurance capacity via enhanced muscle fatigue resistance has not been clarified. In this study, we investigated the effects of HFDs on contractile force and fatigue resistance of slow-twitch dominant muscles. The soleus (SOL) muscle of male C57BL/6J mice fed an HFD (60% kcal from fat) or a low-fat diet (LFD) for 12 weeks was analyzed. Muscle contractile force was measured under resting conditions and during fatigue induced by repeated tetanic contractions (100 Hz, 50 contractions, 2-second intervals). Differences in muscle twitch or tetanic force were not evident between HFD and LFD groups whereas fatigue resistance was higher for the entire end-stage period in the HFD groups. The SOL muscle of HFD-fed mice showed increased levels of markers related to oxidative capacity such as succinate dehydrogenase and citrate synthase activity. In addition, electron microscopy analyses indicated that the total number of mitochondria and mitochondrial volume density increased in the SOL muscle of the HFD groups. These findings suggest that HFD consumption induces increased muscle fatigue resistance in slow-twitch dominant muscle fibers. This effect of HFD may be related to elevated oxidative enzyme activity, high mitochondrial content, or both.

中文翻译：

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高脂饮食小鼠慢肌骨骼肌的收缩力维持和增强的抗疲劳性

食用高脂饮食（HFD）可以显着提高跑步机跑步过程中的运动耐力表现。但是，尚不清楚HFD消耗量是否通过增强的肌肉抗疲劳性来增加耐力。在这项研究中，我们调查了HFD对慢抽搐优势肌肉的收缩力和抗疲劳性的影响。分析了饲喂HFD（脂肪中60％大卡）或低脂饮食（LFD）12周的雄性C57BL / 6J小鼠的比目鱼肌（SOL）。在静止条件下以及在反复的强直性收缩（100 Hz，50次收缩，2秒间隔）引起的疲劳期间测量肌肉收缩力。HFD组和LFD组之间的肌肉抽搐或强直作用力差异不明显，而HFD组的整个终末期的抗疲劳性较高。用HFD喂养的小鼠的SOL肌肉显示与氧化能力相关的标志物水平增加，例如琥珀酸脱氢酶和柠檬酸合酶活性。此外，电子显微镜分析表明，HFD组的SOL肌肉中线粒体总数和线粒体体积密度增加。这些发现表明，食用HFD会导致慢肌支配性肌纤维中增强的抗肌肉疲劳能力。HFD的这种作用可能与氧化酶活性升高，线粒体含量高或两者有关。电镜分析表明，HFD组的SOL肌肉中线粒体总数和线粒体体积密度增加。这些发现表明，食用HFD会导致慢肌支配性肌纤维中增强的抗肌肉疲劳能力。HFD的这种作用可能与氧化酶活性升高，线粒体含量高或两者有关。电镜分析表明，HFD组的SOL肌肉中线粒体总数和线粒体体积密度增加。这些发现表明，食用HFD会导致慢肌支配性肌纤维中增强的抗肌肉疲劳能力。HFD的这种作用可能与氧化酶活性升高，线粒体含量高或两者有关。