title: The effects of aerobic exercise on skeletal muscle metabolism, morphology and in situ endurance in diabetic rats.
abstract: The 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 PointsAerobic training of diabetic animals increased the endurance capacity.Presence of abnormal ultrastructural alterations with diabetes disaapered with regular training.Increased intramyocelluler lipid droplets, high blood glucose level with citrate synthase activity may explain this finding.
authors: Department of Physiology.
authors: Nilay
authors: N
authors: Ergen
authors: Department of Family Medicine, Adana Numune Hospital , Adana, Turkey.
authors: Hatice
authors: H
authors: Kurdak
authors: Department of Physiology.
authors: Seref
authors: S
authors: Erdogan
authors: Department of Histology.
authors: Ufuk Ozgü
authors: UO
authors: Mete
authors: Department of Histology.
authors: Mehmet
authors: M
authors: Kaya
authors: Department of Biochemistry, Faculty of Medicine, University of Cukurova , Adana, Turkey.
authors: Nurten
authors: N
authors: Dikmen
authors: Department of Physiology.
authors: Ayşe
authors: A
authors: Doğan
authors: Department of Physiology.
authors: Sanli Sadi
authors: SS
authors: Kurdak
keywords: Training; citrate synthase; diabetes; muscle endurance; ultrastructure