Combined creatine and protein supplementation in conjunction with resistance training promotes muscle GLUT-4 content and glucose tolerance in humans
1 Exercise Physiology and Biomechanics Laboratory, Department of Kinesiology, Faculty of Physical Education and Physiotherapy, Katholieke Universiteit Leuven, 3001 Leuven, Belgium; and 2 Copenhagen Muscle Research Centre, Institute of Exercise and Sports Sciences, University of Copenhagen, DK-2100...
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Published in | Journal of applied physiology (1985) Vol. 94; no. 5; pp. 1910 - 1916 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
Bethesda, MD
Am Physiological Soc
01.05.2003
American Physiological Society |
Subjects | |
Online Access | Get full text |
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Summary: | 1 Exercise Physiology and Biomechanics Laboratory,
Department of Kinesiology, Faculty of Physical Education and
Physiotherapy, Katholieke Universiteit Leuven, 3001 Leuven,
Belgium; and 2 Copenhagen Muscle Research
Centre, Institute of Exercise and Sports Sciences, University of
Copenhagen, DK-2100 Copenhagen, Denmark
The
present study was undertaken to explore the effects of creatine and
creatine plus protein supplementation on GLUT-4 and glycogen content of
human skeletal muscle. This was investigated in muscles undergoing a
decrease (immobilization) and subsequent increase (resistance training)
in activity level, compared with muscles with unaltered activity
pattern. A double-blind, placebo-controlled trial was performed by 33 young healthy subjects. The subjects' right legs were immobilized with
a cast for 2 wk, followed by a 6-wk resistance training program for the
right knee extensor muscles. The participants were supplemented
throughout the study with either placebo (Pl group) or creatine (Cr
group) or with creatine during immobilization and creatine plus protein
during retraining (Cr+P group). Needle biopsies were
bilaterally taken from the vastus lateralis. GLUT-4 protein expression
was reduced by the immobilization in all groups ( P < 0.05). During retraining, GLUT-4 content increased
( P < 0.05) in both Cr (+24%) and Cr+P (+33%), which
resulted in higher posttraining GLUT-4 expression compared with Pl
( P < 0.05). Compared with Pl, muscle glycogen content was higher ( P < 0.05) in the trained leg in both Cr
and Cr+P. Supplements had no effect on GLUT-4 expression or glycogen content in contralateral control legs. Area under the glucose curve
during the oral glucose tolerance test was decreased from 232 ± 23 mmol · l 1 · min 1
at baseline to 170 ± 23 mmol · l 1
· min 1 at the end of the
retraining period in Cr+P ( P < 0.05), but it did not
change in Cr or Pl. We conclude that creatine intake stimulates GLUT-4
and glycogen content in human muscle only when combined with changes in
habitual activity level. Furthermore, combined protein and creatine
supplementation improved oral glucose tolerance, which is supposedly
unrelated to the changes in muscle GLUT-4 expression.
immobilization; skeletal muscle; glycogen |
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Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-News-3 |
ISSN: | 8750-7587 1522-1601 |
DOI: | 10.1152/japplphysiol.00977.2002 |