Preen D, Dawson B, Goodman C, Lawrence S, Beilby J, Ching S
Department of Human Movement and Exercise Science, The University of Western Australia, Crawley, W.A., 6009, Australia.
Med Sci Sports Exerc. 2001 May;33(5):814-21. doi: 10.1097/00005768-200105000-00022.
This study examined whether creatine (Cr) supplementation could enhance long-term repeated-sprint exercise performance of approximately 80 min in duration.
Fourteen active, but not well-trained, male subjects initially performed 10 sets of either 5 or 6 x 6 s maximal bike sprints, with varying recoveries (24, 54, or 84 s between sprints) over a period of 80 min. Work done (kJ) and peak power (W) were recorded for each sprint, and venous blood was collected preexercise and on four occasions during the exercise challenge. Muscle biopsies (vastus lateralis) were obtained preexercise as well as 0 min and 3 min postexercise. Subjects were then administered either 20 g.d-1 Cr.H2O (N = 7) or placebo (N = 7) for 5 d. Urine samples were collected for each 24 h of the supplementation period. Subjects were then retested using the same procedures as in test 1.
Total work done increased significantly (P < 0.05) from 251.7 +/- 18.4 kJ presupplementation to 266.9 +/- 19.3 kJ (6% increase) after Cr ingestion. No change was observed for the placebo group (254.0 +/- 10.4 kJ to 252.3 +/- 9.3 kJ). Work done also improved significantly (P < 0.05) during 6 x 6 s sets with 54-s and 84-s recoveries and approached significance (P = 0.052) in 5 x 6 s sets with 24-s recovery in the Cr condition. Peak power was significantly increased (P < 0.05) in all types of exercise sets after Cr loading. No differences were observed for any performance variables in the placebo group. Resting muscle Cr and PCr concentrations were significantly elevated (P < 0.05) after 5 d of Cr supplementation (Cr: 48.9%; PCr: 12.5%). Phosphocreatine levels were also significantly higher (P < 0.05) immediately and 3 min after the completion of exercise in the Cr condition.
The results of this study indicate that Cr ingestion (20 g.day-1 x 5 d) improved exercise performance during 80 min of repeated-sprint exercise, possibly due to an increased TCr store and improved PCr replenishment rate.
本研究旨在探讨补充肌酸（Cr）是否能提高持续约80分钟的长期重复冲刺运动表现。
14名活跃但未经充分训练的男性受试者，最初进行10组5次或6次×6秒的最大强度自行车冲刺，在80分钟内冲刺间恢复时间不同（24秒、54秒或84秒）。记录每次冲刺的做功（kJ）和峰值功率（W），并在运动前和运动挑战期间的四个时间点采集静脉血。在运动前以及运动后0分钟和3分钟获取肌肉活检样本（股外侧肌）。然后受试者连续5天服用20克·天⁻¹的Cr·H₂O（N = 7）或安慰剂（N = 7）。在补充期间，每24小时收集一次尿液样本。然后使用与测试1相同的程序对受试者进行重新测试。
补充Cr后，总做功从补充前的251.7±18.4 kJ显著增加（P < 0.05）至266.9±19.3 kJ（增加6%）。安慰剂组未观察到变化（254.0±10.4 kJ至252.3±9.3 kJ）。在Cr条件下，6次×6秒且恢复时间为54秒和84秒的组中，做功也显著改善（P < 0.05），在恢复时间为24秒的5次×6秒的组中接近显著水平（P = 0.052）。Cr负荷后，所有类型运动组的峰值功率均显著增加（P < 0.05）。安慰剂组的任何性能变量均未观察到差异。补充Cr 5天后，静息肌肉Cr和磷酸肌酸（PCr）浓度显著升高（P < 0.05）（Cr：48.9%；PCr：12.5%）。在Cr条件下，运动结束后即刻和3分钟时，磷酸肌酸水平也显著更高（P < 0.05）。
本研究结果表明，摄入Cr（20克·天⁻¹×5天）可改善80分钟重复冲刺运动期间的运动表现，可能是由于总肌酸（TCr）储备增加和磷酸肌酸补充率提高。
