Administration of glucose, glucose plus branched-chain amino acids
or placebo and their effects on bike performance over 100 km.
Madsen, Klavs, Dave A. Maclean, Bente Kiens, and Dirk Christensen.
Department of Physical Education, Odense University, Denmark,
Copenhagen Muscle Research Center, Rigshospitalet, August Krogh
Institute, University of Copenhagen, Copenhagen Denmark
APStracts 3:0423A, 1996.
This study was undertaken to determine the effects of ingesting either
glucose (G) or glucose plus branched-chain amino acids (B) compared
to placebo (P) during prolonged exercise. Nine well-trained cyclists
with a maximal oxygen uptake of 63.1 +/- 1.5 ml O2/min/kg performed
three laboratory trials consisting of 100 km cycling separated by 7
days between each trial. During these trials, the subjects were
encouraged to complete the 100 km as fast as possible on their own
bicycles connected to a magnetic brake. No differences in performance
times were observed between the three trials (160.1 +/- 4.1, 157.2
+/- 4.5 and 159.8 +/- 3.7 min, respectively). In the B trial, plasma
BCAA levels increased from 339 +/- 28 [mu]M at rest to 1026 +/- 62
[mu]M after exercise (P<0.01). Plasma ammonia concentrations
increased during the entire exercise period for all three trials, and
were significantly higher in trial B compared with trial G and P
(P<0.05). The respiratory exchange ratio was similar in the
three trials during the first 90 min of exercise, thereafter it
tended to drop more in the P trial than in the G and B trials. These
data suggest that neither glucose or glucose plus BCAA ingestion
during 100 km cycling can enhance performance in well-trained
cyclists.
Received 14 May 1996; accepted in final form 13 August 1996.
APS Manuscript Number A459-6.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 7 October 1996