EFFECTS OF ENDURANCE TRAINING ON HISTOCHEMICAL PROPERTIES OF RAT SKELETAL MUSCLE

Abstract

Wistar rats (30 days after birth) were trained by treadmill running for fifteen weeks. The training program consisted of endurance running at a speed of 30 meters per minute, for 30 minutes a day, and 5 days a week. After the training, fiber composition and fiber area of thier leg muscles were histochemically studied.
Samples of the soleus, EDL, and plantaris muscles were stained with succinate dehydrogenase (SDH) and myosin ATPase, and the muscle fibers were classified into the three types : fast-twitch glycolytic (FG), fast-twitch oxydative glycolytic (FOG), and slow-twitch oxydative (SO) .
The body and muscle weights of the rats in the training group were larger than those of the control group, but the difference was not significant.
After the training, the ratio among the numbers of three fiber types showed no difference between the training and control groups. Also, the average cross-sectional areas of the FG fibers showed no difference between the training and control groups ; however, those of the FOG and SO fibers were 8-11% larger in the training group than in the control group.
These results obtained in the present experiments indicated that the trained rats increased in their fatigue resistivity through the training.