Recently, administration of nicotinic acid (NA) at a pharmacological dose was found to induce a similar change in the muscle´s contractile and metabolic phenotype as observed in response to endurance exercise. Thus, the hypothesis was tested that combined NA administration and endurance exercise promotes the adaptation of muscle to regular exercise and improves the endurance performance to a greater extent than exercise alone. Thus, 30 adult mice were randomly divided into three groups of 10 mice/group. The control and the exercise (EX) group received an adequate NA diet, while the EX + NA group received a high NA diet. Mice of the EX and the EX + NA group were subjected to a treadmill endurance exercise program five times/week during the experimental period of 42 days. At day 41, endurance performance was greater in the EX + NA group than in the control and the EX group (p < 0.05). Mice of the EX + NA group had a higher type IIA (+60%) and a lower type IIB (−55%) fiber percentage in gastrocnemius (GN) muscle than control mice (p < 0.05), while the type I fiber percentage in GN muscle tended to be increased (+100%) in the EX + NA group compared to the control group (p = 0.051). In the EX + NA group, glycogen concentration (+15%) and mRNA levels of two glycolytic (+70–80%) and two glycogenolytic enzymes (+80–120%) in GN muscle were increased compared to the control group (p < 0.05). In conclusion, feeding a high NA diet induces changes in skeletal muscle fiber composition and improves endurance performance of mice subjected to regular endurance exercise.

中文翻译：

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烟酸改善了跑步机运动小鼠的耐力表现。

最近，发现以药理剂量施用烟酸（NA）可以诱导肌肉的收缩和代谢表型发生类似的变化，这是对耐力运动的反应所观察到的。因此，检验了以下假设：与单独运动相比，NA施用和耐力运动相结合可促进肌肉适应常规运动，并在更大程度上改善耐力性能。因此，将30只成年小鼠随机分为三组，每组10只小鼠。对照组和运动组（EX）接受足够的NA饮食，而EX + NA组则接受高NA饮食。EX和EX + NA组的小鼠在42天的实验期内每周接受五次跑步机耐力锻炼程序。在第41天，p＜0.05）。EX + NA组的小鼠腓肠肌（GN）肌肉中IIA型纤维（+ 60％）和IIB型纤维百分比（-55％）低于对照组小鼠（p <0.05），而I型纤维百分比与对照组相比，EX + NA组的GN肌肉中的NF趋于增加（+ 100％）（p = 0.051）。与对照组相比，EX + NA组的GN肌肉中糖原浓度（+ 15％）和两种糖酵解（+ 70–80％）和两种糖原分解酶（+ 80–120％）的mRNA水平增加（p <0.05）。总之，喂养高NA饮食会引起骨骼肌纤维成分的变化，并改善经受常规耐力运动的小鼠的耐力性能。