The effect of treadmill running and swimming on citrate synthase activity and glycogen levels in the rat
Thirty-eight female Wistar rats were studied to determine the response of citrate synthase (CS) and glycogen (GLY) to two similar programs of endurance training. Animals were randomly assigned to one of three groups: run-trained (RUN), swim-trained (SWIM) or sedentary control (CON). The treadmill trained animals ran at a speed of 27 m/min. up an eight degree incline. The swim-trained animals swam with 2% of body weight attached to their tails. The duration of the exercise protocols was 2 hours/day, the frequency 5 days/week and the length of the training regimen was 10 weeks. Liver GLY content (mmoles/g) for the exercise trained groups was significantly higher (p < 0.01) than CON. There were no significant differences between RUN and SWIM animals in the GLY levels of the hindlimb muscles. The GLY levels of the forelimb muscles were significantly greater (p0.01) in the SWIM animals compared to the RIJN animals, apart from the pectoralis (EEC). The CS activity in the soleus (SOL) and red -vastus (RV) of the RUN animals was significantly larger (p <; 0.01) than SWIM. The plantaris (PLANT) of the SWIM animals had significantly greater CS activity than the RUN animals. In the forelimb muscles, only -the deltoid (DEL) of the SWIM group was higher in CS activity than the RUN groups. The results of this study indicate that the mechanisms responsible for increased GLY storage in skeletal muscle are under independent control to those factors governing the changes in the oxidative enzyme CS. Differences in muscle GLY levels and CS activity between RUN and SWIM rats can be explained by contrasting mechanics in these two (nodes of exercise and the resulting fiber recruitment patterns.