Differences in effects of various training regimens on metabolism of skeletal muscles.

The purpose of the study was to detect the specific nature of the action of various training regimens on glycogen, activities of phosphofructokinase (PFK) and myofibrillar Ca(2+)-ATPase, and Ca2+ accumulation by the sarcoplasmic reticulum in muscle fibers of various types. Models of sprint, interval or aerobic continuous running training for 10 weeks, as well as a model of fast strength training (repeated fast clambering up a slope of 80 degrees) and swimming training for 6 weeks were applied in Wistar rats. Most of the training regimes used caused increases in glycogen content both in the soleus muscle (SO) by 29 ... 199% and in the white part of the quadriceps muscle (FG) by 37 ... 65%. Only sprint training was ineffective in both muscles and aerobic running in FG fibers. All training regimes, including sprint training, increased the glycogen content of the sarcoplasmic reticulum (SPR). A significant suppression of PFK activity was found 48 hours after interval or aerobic running in both muscles and after sprint running in the soleus (by 26 ... 62%). However, 4-min highly intensive test running (60 m.s-1) resulted in 2-3 fold increases in PFK activity of both muscles in rats trained by interval or continuous running but not in sprint trained and sedentary animals. It was suggested that training in intensive interval running or aerobic running enhances the sensitivity of PFK both to inhibitory and activating influences. The activity of Ca(2+)-ATPase increased as a result of sprint, interval, continuous running and strength training and decreased in result of continuous swimming. The rate of Ca2+ accumulation by SPR increased with sprint, interval, aerobic running and fast strength training in SO and with fast strength training in FG fibers.