Sixty-nine female Wistar rats were studied to determine if the oxidative capacity and glycogen concentration of skeletal muscle was affected by either an increase or decrease in training duration following a 9 wk program of treadmill running. Initially, 30 rats were randomly assigned to one of three sedentary control groups. Subgroups (N=10) of sedentary animals were kept inactive and were sacrificed at week 0 (Cl), week 9 (C2) and week 11 (C3) of the study. Thirty-nine rats were initially trained 5 days/wk for 9 wks using a standard exercise protocol. At the end of 9 wks of treadmill running, endurance trained animals were separated into four groups: 1) Eleven rats (ET) were killed. 2) Ten rats (CT) continued to train for 2 additional weeks following the same protocol and were killed at the end of 11 wks of training. 3) Ten rats (DT) decreased the duration of daily running by 66% and after 14 days were killed. 4) Eight rats (IT) increased the duration of daily running by 500% in an attempt to simulate overtraining in humans, and after 6 days were killed. The respiratory capacity (Qo2) and citrate synthase activity (CSA) of the soleus (SOL) and plantaris (PLANT) muscles were significantly increased (p< 0.05) over all control groups by nine weeks of treadmill running (ET). The Qo2 and CSA of CT rats were significantly higher than all control groups, and the PLANT CSA was significantly higher (p< 0.05) than ET rats. The SOL and PLANT Qo2 and CSA remained significantly higher (p< 0.05) than all control groups with fourteen days of decreased training. Six days of increased training significantly increased (p< 0.05) SOL and PLANT Qo2 and CSA over all control groups. In addition IT rats had SOL and PLANT CSA that were significantly higher (p< 0.05) than ET rats. The SOL and WV glycogen concentrations were unaffected by all training protocols. Only the CT and IT PLANT and liver had significantly more (p< 0.05) glycogen than all sedentary control groups. The results of this study indicate that the rat is a very adaptable animal, and to thoroughly study it as a possible model for the study of overtraining in humans would require an examination of various exercise protocols. In addition, the exercise-induced increase in the oxidative capacity of trained skeletal muscle is not readily reversible during decreased training.
| Identifer | oai:union.ndltd.org:BSU/oai:cardinalscholar.bsu.edu:handle/183232 |
| Date | January 1986 |
| Creators | Morse, Willis Michael |
| Contributors | Costill, David L. |
| Source Sets | Ball State University |
| Detected Language | English |
| Format | vii, 53 leaves ; 28 cm. |
| Source | Virtual Press |
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