Creatine ingestion favorably affects performance and muscle metabolism during maximal exercise in humans.

@article{Casey1996CreatineIF,
  title={Creatine ingestion favorably affects performance and muscle metabolism during maximal exercise in humans.},
  author={Anna Casey and Dumitru Constantin-Teodosiu and Sandra Howell and Eric Hultman and Paul L. Greenhaff},
  journal={The American journal of physiology},
  year={1996},
  volume={271 1 Pt 1},
  pages={
          E31-7
        }
}
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… 

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...

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