EFFECTS OF POTASSIUM-ASPARTATE SALT ADMINISTRATION ON GLYCOGEN USE INTHE RAT DURING A SWIMMING STRESS

The ergogenic effect of aspartate salts on performance during prolonge d exercise is still controversial. Potential mechanisms of the suggest ed ergogenic effect of aspartate on exercise performance are a sparing of muscle glycogen stores or its faster resynthesis during exercise. The purpose of this study was to determine whether aspartate causes a sparing of muscle glycogen during exercise. Six groups of rats were st udied: one group received a single injection of aspartate (1 g . kg-1, IP) and was then sacrificed at rest, a second group of aspartate-trea ted rats was sacrificed after a 60-min swim. The third and fourth grou ps were given an injection of physiological saline and then sacrificed respectively at rest and after a 60-min swim. The fifth and sixth gro ups were given an aspartate or a saline injection and then sacrificed after swimming to exhaustion. The exhaustion times after saline (178.9 +/- 38.2 min) and aspartate (174.4 +/- 45.2 min) were not significant ly different. Results did not confirm an ergogenic effect of a single dose of aspartate on swimming endurance in the rat. Aspartate-treated rats had a significantly lower plasma FFA concentration after swimming to exhaustion when compared to control rats (respectively, 0.70 +/- 0 .25 vs. 1.16 +/- 0.45 mM). Also, the results of the present study do n ot support the hypothesis of a sparing of muscle or fiver glycogen wit h aspartate, because a similar content of glycogen remained in the mus cles and liver of control rats after a 60-min swim or after swimming t o exhaustion.