Institute of Exercise Physiology and Wellness, Educational and Human Sciences, Sport and Exercise Science, University of Central Florida, 12494 University Blvd., Orlando, FL 32816, USA.
Department of Internal Medicine, College of Medicine, University of Central Florida, Orlando, FL 32816, USA.
Nutrients. 2017 Sep 7;9(9):988. doi: 10.3390/nu9090988.
Carnosine is a naturally occurring intramuscular dipeptide that is thought to attenuate fatigue during high-intensity exercise. Carnosine content is influenced by various factors, including gender and diet. Despite research reporting that carnosine content is lower in women compared to men and lower in vegetarians compared to omnivores, no investigations have examined carnosine content in women based on dietary protein intake and its effect on muscle fatigue. Twenty recreationally active women were assigned to either a high (HI; n = 5), moderate (MOD; n = 10), or low (LO; n = 5) group based upon intramuscular carnosine content of the vastus lateralis. Each participant underwent two unilateral maximal voluntary isometric contractions (MVIC) of the knee extensors separated by an isokinetic exercise protocol consisting of five sets of 50 repeated maximal unilateral contractions. Magnitude-based inferences were used to analyze group differences. Percent decline in rate of force development and peak torque (PT) during the MVICs and changes in PT and mean torque during the muscle-fatiguing protocol were lower in HI compared to both MOD and LO. Additionally, absolute and relative dietary protein intake were greater in HI compared to MOD or LO. Results indicated that greater intramuscular carnosine content was reflective of greater dietary protein intake and that individuals with higher carnosine content displayed a greater attenuation of fatigue compared to those with lower carnosine.
肌肽是一种天然存在于肌肉中的二肽，被认为可以减轻高强度运动中的疲劳。肌肽含量受多种因素影响，包括性别和饮食。尽管有研究报告称，女性的肌肽含量低于男性，素食者的肌肽含量低于杂食者，但尚无研究根据饮食蛋白质摄入量和对肌肉疲劳的影响来检测女性的肌肽含量。20 名有规律运动的女性根据股外侧肌的肌肽含量被分为高（HI；n = 5）、中（MOD；n = 10）或低（LO；n = 5）组。每位参与者都进行了两次单侧最大自主等长收缩（MVIC），然后进行等速运动协议，包括 5 组 50 次重复的最大单侧收缩。使用基于幅度的推断分析组间差异。与 MOD 和 LO 相比，HI 组在 MVIC 期间的力发展速率和峰值扭矩（PT）下降百分比以及肌肉疲劳协议期间的 PT 和平均扭矩变化较小。此外，HI 组的绝对和相对膳食蛋白质摄入量均高于 MOD 或 LO。结果表明，较高的肌肉肌肽含量反映了较高的膳食蛋白质摄入量，并且较高肌肽含量的个体与较低肌肽含量的个体相比，疲劳的缓解程度更大。
