Maganaris C N, Maughan R J
University Medical School, University of Aberdeen, Foresterhill, UK.
Acta Physiol Scand. 1998 Jul;163(3):279-87. doi: 10.1046/j.1365-201x.1998.00395.x.
The present study examined the hypothesis that creatine (Cr) supplementation can increase the performance of isometric exercise in subjects engaged in a strength training program. Ten male subjects were tested in three experimental trials 7 days apart (days 1, 8 and 15). In each trial the subjects' maximum voluntary force of contraction (MVC) was measured in both legs and isometric endurance capacity at 80, 60, 40 and 20% of MVC of their stronger leg (knee extensor group) was measured with a 4-min rest between contractions. Additionally, the subjects' isometric endurance capacity at 80% of MVC of their weaker leg was measured in 10 repeated bouts interspersed with 2-min rest. A double-blind cross-over design was adopted for administering Cr or placebo. Subjects were randomized into either the Cr-placebo (Group A: days 2-6: 10 g day-1 of Cr; days 9-13: 10 g day-1 of glucose polymers) or the placebo-Cr group (Group B reverse supplementation order). The daily diet was analysed, and urine samples from 24-h collections were subjected to Cr and creatinine analysis. In each subject, approximately 18 g (35%) of Cr was eliminated in the urine during the Cr supplementation period. MVC increased by about 10% (P < 0.01 in the weaker leg, P < 0.05 in the stronger leg) and body mass increased by 1.7 +/- 0.4 kg (2.3%, P < 0.01) and 1.8 +/- 0.3 kg (2.1%, P < 0.01) in groups A and B, respectively, after Cr supplementation, while energy intake and diet composition remained constant throughout the study. The subjects' endurance capacity increased (P < 0.05) in all the bouts after Cr supplementation. Muscle hypertrophy in response to Cr supplementation and weight training may explain the findings of the present study.
补充肌酸（Cr）可提高参与力量训练计划的受试者的等长运动表现。10名男性受试者在相隔7天的三项实验性试验（第1天、第8天和第15天）中接受测试。在每次试验中，测量受试者双腿的最大自主收缩力（MVC），并以其较强腿（膝伸肌群）MVC的80%、60%、40%和20%测量等长耐力，每次收缩之间休息4分钟。此外，在较弱腿MVC的80%水平下，以10次重复发作、每次发作之间休息2分钟的方式测量受试者的等长耐力。采用双盲交叉设计给予Cr或安慰剂。受试者被随机分为Cr-安慰剂组（A组：第2 - 6天：每天10克Cr；第9 - 13天：每天10克葡萄糖聚合物）或安慰剂-Cr组（B组，补充顺序相反）。分析每日饮食，并对24小时收集的尿液样本进行Cr和肌酐分析。在补充Cr期间，每个受试者尿液中约有18克（35%）的Cr被排出。补充Cr后，A组和B组的MVC分别增加约10%（较弱腿P < 0.01，较强腿P < 0.05），体重分别增加1.7±0.4千克（2.3%，P < 0.01）和1.8±0.3千克（2.1%，P < 0.01），而在整个研究过程中能量摄入和饮食组成保持不变。补充Cr后，受试者在所有发作中的耐力均有所提高（P < 0.05）。补充Cr和进行重量训练后出现的肌肉肥大可能解释了本研究的结果。
