Casey A, Constantin-Teodosiu D, Howell S, Hultman E, Greenhaff P L
Department of Physiology and Pharmacology, University of Nottingham Medical School, Queen's Medical Center, United Kingdom.
Am J Physiol. 1996 Jul;271(1 Pt 1):E31-7. doi: 10.1152/ajpendo.1996.271.1.E31.
Nine male subjects performed two bouts of 30-s maximal isokinetic cycling before and after ingestion of 20 g creatine (Cr) monohydrate/day for 5 days. Cr ingestion produced a 23.1 +/- 4.7 mmol/kg dry matter increase in the muscle total creatine (TCr) concentration. Total work production during bouts 1 and 2 increased by approximately 4%, and the cumulative increases in both peak and total work production over the two exercise bouts were positively correlated with the increase in muscle TCr. Cumulative loss of ATP was 30.7 +/- 12.2% less after Cr ingestion, despite the increase in work production. Resting phosphocreatine (PCr) increased in type I and II fibers. Changes in PCr before exercise bouts 1 and 2 in type II fibers were positively correlated with changes in PCr degradation during exercise in this fiber type and changes in total work production. The results suggest that improvements in performance were mediated via improved ATP resynthesis as a consequence of increased PCr availability in type II fibers.
9名男性受试者在连续5天每天摄入20克一水肌酸（Cr）前后，进行了两轮30秒的最大等速骑行。摄入Cr后，肌肉总肌酸（TCr）浓度每千克干物质增加了23.1±4.7毫摩尔。第一轮和第二轮骑行期间的总功输出增加了约4%，两轮运动中峰值和总功输出的累积增加与肌肉TCr的增加呈正相关。尽管功输出增加，但摄入Cr后ATP的累积损失减少了30.7±12.2%。I型和II型纤维的静息磷酸肌酸（PCr）增加。II型纤维在第一轮和第二轮运动前PCr的变化与该纤维类型运动期间PCr降解的变化以及总功输出的变化呈正相关。结果表明，运动表现的改善是通过II型纤维中PCr可用性增加从而改善ATP再合成来介导的。
