Bissonnette D J, Madapallimatam A, Jeejeebhoy K N
Department of Nutritional Science, University of Toronto, Canada.
Am J Clin Nutr. 1997 Aug;66(2):293-303. doi: 10.1093/ajcn/66.2.293.
Studies using nuclear magnetic resonance have shown that undernutrition affects muscle performance and energetics. It is unclear to what extent underfeeding and refeeding influence the availability of muscle glycogen, net glycogenolysis, skeletal muscle wasting, and recovery. We hypothesized that muscle performance is independent of muscle size and weight, is specific to muscle type, and is unrelated to muscle glycogen concentrations. Slow- and fast-twitch muscles were studied in three groups of adult male Wistar rats: well-fed controls, hypoenergetically fed (Hypo) rats, and rats refed for 4 d after the hypoenergetic diet. Glycogen concentrations and net glycogenolysis; serum glucose, insulin, and protein concentrations; and muscle weight, protein, and cross-sectional area were studied relative to the performance of both types of muscles. Our study controlled for muscle size, weight, and type and electrolyte-micronutrient deficiency. Undernutrition affected muscle performance in five ways. First, compared with controls, fatigue increased only in the soleus muscles of Hypo rats yet the maximal relaxation rate (MRR) decreased in both the soleus and extensor digitorum longus (EDL) muscles. Second, muscle glycogen concentrations did not significantly correlate with fatigue in either the soleus or the EDL although net glycogenolysis was significantly correlated with fatigue in the soleus (r = -0.64; P > 0.01 < 0.05). Third, lower glycogen concentrations did not hinder net glycogenolysis in the EDL of Hypo rats or the soleus of refed rats. Fourth, muscle weight, size, and protein were dissociated from function. Fifth, refeeding did not restore muscle endurance; however, the MRR of the soleus normalized. In conclusion, glycogen values and muscle performance did not correlate but net glycogenolysis correlated with fatigue in the soleus. Also, there was a dissociation between muscle weight, size, and protein and muscle function during hypoenergetic feeding and refeeding.
使用核磁共振的研究表明，营养不足会影响肌肉性能和能量代谢。目前尚不清楚进食不足和再喂养对肌肉糖原可用性、净糖原分解、骨骼肌消瘦和恢复的影响程度。我们假设肌肉性能与肌肉大小和重量无关，具有肌肉类型特异性，且与肌肉糖原浓度无关。在三组成年雄性Wistar大鼠中研究了慢肌和快肌：正常喂养的对照组、低能量喂养（Hypo）的大鼠以及在低能量饮食后再喂养4天的大鼠。相对于两种类型肌肉的性能，研究了糖原浓度和净糖原分解；血清葡萄糖、胰岛素和蛋白质浓度；以及肌肉重量、蛋白质和横截面积。我们的研究控制了肌肉大小、重量、类型以及电解质 - 微量营养素缺乏情况。营养不足通过五种方式影响肌肉性能。首先，与对照组相比，仅Hypo大鼠的比目鱼肌疲劳增加，而比目鱼肌和趾长伸肌（EDL）的最大舒张速率（MRR）均降低。其次，比目鱼肌或EDL中的肌肉糖原浓度与疲劳均无显著相关性，尽管比目鱼肌中的净糖原分解与疲劳显著相关（r = -0.64；P > 0.01 < 0.05）。第三，较低的糖原浓度并未阻碍Hypo大鼠EDL或再喂养大鼠比目鱼肌中的净糖原分解。第四，肌肉重量、大小和蛋白质与功能分离。第五，再喂养并未恢复肌肉耐力；然而，比目鱼肌的MRR恢复正常。总之，糖原值与肌肉性能不相关，但比目鱼肌中的净糖原分解与疲劳相关。此外，在低能量喂养和再喂养期间，肌肉重量、大小、蛋白质与肌肉功能之间存在分离。
