Effect of 7-10 days of cycle ergometer exercise on skeletal muscle
glut-4 protein content.
Gulve, Eric A., and Robert J. Spina.
Section of Applied Physiology, Department of Medicine, and Irene
Walter Johnson Research Institute of Rehabilitation, Washington
University School of Medicine
APStracts 2:0265A, 1995.
Previous studies in animals and humans have shown that endurance
exercise training protocols of several weeks to many months in
duration induce adaptive increases in skeletal muscle GLUT-4 protein
concentration. It is generally assumed that the increase in GLUT-4
concentration is a long-term adaptation to training. The present
study examined whether 7-10 d of cycle ergometer exercise could
induce increases in skeletal muscle GLUT-4 levels. Eight healthy
subjects (4 males, 4 females) aged 31 +/-2 yr (mean +/- SE) exercised
2h daily at 65-70% of O2 peak for either 7 (n=5) or 10 (n=3)
consecutive days. Muscle biopsies (vastus lateralis) were obtained
before initiating the exercise program and 36-48 h after the final
bout of exercise. Glucose transporter protein was quantitated by
Western blotting using antiserum specific for GLUT-4. O2 peak was
increased by 10% (from 3.0 +/- 0.2 to 3.3 +/- 0.2 L min-1;
p<0.01) in response to the training. Body weight did not change
(74.3 +/- 4.6 before vs. 75.0 +/-4.2 kg after) as a result of
training. Muscle GLUT-4 immunoreactivity was increased 98% (from 584
+/- 50 to 1154 +/- 40 125I-cpm/25[mu]g protein; p<0.001) in
response to training. Increases in O2 peak and GLUT-4 protein were
similar for 7 and 10 d of training. These results suggest that, given
an adequate training stimulus, adaptations in skeletal muscle GLUT-4
protein occur very rapidly. Furthermore, the increase in GLUT-4 after
7-10 d of exercise is as large as that reported in studies employing
long-term training protocols.
Received 19 April 1995; accepted in final form 12 June 1995.
APS Manuscript Number A426-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.