Creatine supplementation favourably affects performance and muscle
metabolism during maximal intensity exercise in humans.
Casey, A., D. Constantin-Teodosiu, S. Howell, E. Hultman, and P. L.
Greenhaff.
Department of Physiology and Pharmacology, University of Nottingham
Medical School, Queen's Medical Center, Nottingham NG7 2UH, United
Kingdom; Department of Clinical Chemistry, Huddinge University
Hospital, Karolinska Institute S-141 86, Huddinge, Sweden
APStracts 3:0062E, 1996.
Nine male subjects performed 2 bouts of 30 s maximal, isokinetic
cycling, before and after ingestion of 20g creatine monohydrate
(Cr)/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 4% and the
cumulative increases in both peak and total work production over the
2 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 prior to 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
improvements in performance were mediated via improved ATP
resynthesis as a consequence of increased PCr availability in type II
fibers.
Received 21 August 1995; accepted in final form 7 February 1996.
APS Manuscript Number E405-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96