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effects of aerobic exercise training on skeletal muscle endurance
capacity were examined in diabetic rats in situ. Moderate diabetes
was induced by iv injection of streptozotocin and an exercise
training program on a treadmill was carried out for 8 weeks. The animals
randomly assigned to one of the four experimental groups: control-sedentary
(CS), control-exercise (CE), diabetic-sedentary (DS) or diabetic-exercise
(DE). The changes in the muscle endurance capacity were evaluated
through the square wave impulses (supramaximal) of 0.2-ms duration
at 1 Hz in the in situ gastrocnemius-soleus muscle complex.
Muscle was stimulated continuously until tension development reduced
to the half of this maximal value. Time interval between the beginning
and the end of stimulation period is defined as contraction duration.
Following the training period, blood glucose level reduced significantly
in the DE group compared to DS group (p < 0.05). The soles muscle
citrate synthase activity was increased significantly in both of the
trained groups compared to sedentary animals (p < 0.05). Fatigued
muscle lactate values were not significantly different from each other.
Ultrastractural abnormality of the skeletal muscle in DS group disappeared
with training. Presence of increased lipid droplets, mitochondria
clusters and glycogen accumulation was observed in the skeletal muscle
of DE group. The contraction duration was longer in the DE group than
others (p < 0.001). Fatigue resistance of exercised diabetic animals
may be explained by increased intramyocellular lipid droplets, high
blood glucose level and muscle citrate synthase activity.
KEY
WORDS: Training, citrate synthase, muscle endurance, ultrastructure,
diabetes.
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