Caffeine counteracts the ergogenic action of muscle creatine
loading.
Vandenberghe, K., N. Gillis, M. Van Leemputte, P. Van Hecke, F.
Vanstapel, and P. Hespel.
Faculty of Physical Education and Physiotherapy, Department of
Kinesiology and Faculty of Medicine, Biomedical N.M.R. Unit,
Katholieke Universiteit Leuven, B-3001 Leuven, Belgium
APStracts 2:0439A, 1995.
This study aimed to compare the effects of oral creatine
supplementation with creatine supplementation in combination with
caffeine on muscle phosphocreatine level (PCr) and performance in
healthy male volunteers (N=9). Before and after 6 days of placebo
(P), creatine (0.5 g/kg.day)(C), or creatine (0.5 g/kg.day) plus
caffeine (5 mg/kg.day)(CC) supplementation, 31P-NMR spectroscopy of
the M. Gastrocnemius and a maximal intermittent exercise fatigue-test
of the knee-extensors on an isokinetic dynamometer were performed.
The exercise consisted of 3 consecutive maximal isometric
contractions and 3 interval-series of 90, 80 and 50 maximal voluntary
contractions, performed with a rest interval of 2 min in between the
series. Muscle [ATP] remained constant over the 3 experimental
conditions. C and CC increased (p<0.05) muscle [PCr] by 4-6 %.
Dynamic torque production, however, was increased by 10-23 %
(p<0.05) by C but was not changed by CC. Torque improvement
during C was most prominent immediatly after the 2 min rest-periods
in between the exercise bouts. The data show creatine supplementation
to elevate muscle [PCr] and to markedly improve performance during
intense intermittent exercise. This ergogenic effect, however, is
completely eliminated by caffeine intake.
Received 15 June 1995; accepted in final form 26 September 1995.
APS Manuscript Number A636-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95