Schneider D A, McDonough P J, Fadel P J, Berwick J P
Exercise Science Research Laboratory, School of Exercise Science, Griffith University, Gold Coast, Qld, Australia.
Aust J Sci Med Sport. 1997 Sep;29(3):65-8.
Nine untrained male subjects participated in a placebo (Pl)/creatine (Cr), single-blind study conducted over a 5-wk period. Placebo and Cr treatments were presented in a sequential manner because muscle Cr washout time after supplementation is unknown. The mean ( +/- SE) age, height, and initial body mass for the subjects was 25.7+/- 1.2 yr, 177 +/- 2 cm, and 78.5 +/- 3.8 kg, respectively. Each subject performed five 15-s bouts of maximal cycling (1-min rest periods) after 7 d of Pl (6 g glucose X 5 doses daily) and again after ingesting Cr for 7 d (5 g creatine plus 1 g glucose X 5 doses) with a 2-wk intervention period. Only 6 of 9 subjects were able to complete five 1-min bouts of maximal cycling (5-min rest periods) after an additional 2 d of Pl and Cr treatment. Cr ingestion resulted in a significant increase in the work performed during each 15-s bout of maximal cycling compared to Pl trials. Moreover, the total work completed during five 15-s bouts of cycling increased significantly from 47.5 +/- 2.3 kJ with Pl treatment to 50.6 +/- 2.3 kJ after Cr supplementation (P < 0.05). Peak blood lactate concentrations determined 4 min after the fifth 15-s work bout were 14.4 +/- 0.5 mmol.L-1 and 14.3 +/- mmol.L-1 for Pl and Cr trials, respectively (P < 0.05). Total work completed during five 1-min bouts of maximal cycling was not significantly increased after Cr supplementation (P > 0.05). Additionally, Cr supplementation did not slow the rate of decline in the work accomplished during repeated bouts of maximal cycling. These findings suggest that Cr ingestion may augment the rate of ATP resynthesis from phosphocreatine during exercise in untrained subjects.
九名未经训练的男性受试者参与了一项为期5周的安慰剂（Pl）/肌酸（Cr）单盲研究。由于补充后肌肉中肌酸的清除时间未知，安慰剂和肌酸治疗以序贯方式进行。受试者的平均（±标准误）年龄、身高和初始体重分别为25.7±1.2岁、177±2厘米和78.5±3.8千克。在服用安慰剂7天（每日6克葡萄糖×5剂）后，以及在摄入肌酸7天（5克肌酸加1克葡萄糖×5剂）并经过2周干预期后，每个受试者进行了五次15秒的最大强度骑行（休息1分钟）。在额外进行2天的安慰剂和肌酸治疗后，9名受试者中只有6人能够完成五次1分钟的最大强度骑行（休息5分钟）。与安慰剂试验相比，摄入肌酸导致每次15秒最大强度骑行期间的做功显著增加。此外，五次15秒骑行期间完成的总功从安慰剂治疗时的47.5±2.3千焦显著增加到补充肌酸后的50.6±2.3千焦（P<0.05）。在第五次15秒做功回合后4分钟测定的峰值血乳酸浓度，安慰剂试验和肌酸试验分别为14.4±0.5毫摩尔/升和14.3±毫摩尔/升（P<0.05）。补充肌酸后，五次1分钟最大强度骑行期间完成的总功没有显著增加（P>0.05）。此外，补充肌酸并没有减缓重复最大强度骑行回合期间做功下降的速率。这些发现表明，在未经训练的受试者运动期间，摄入肌酸可能会提高磷酸肌酸合成ATP的速率。
