مرکز منطقه ای اطلاع رساني علوم و فناوري - THE EFFECT OF NORMOBARIC HYPOXIC TRAINING ON ELECTRICAL STIMULATION INDUCED SKELETAL MUSCLE FATIGUE IN RATS

Abstract :

Objective: The aim of this study was to investigate the effect of normobaric hypoxic training (altitude training) on skeletal muscle fatigue and peak force induced by electrical stimulation in rats. Material and Method: A total of 22 Sprague Dawley male rats were randomly divided into 4 groups: Control (LL, n=5), live low-train low (LLTL, n=6), live hypoxia-train hypoxia (LHTH, n=5), live hypoxia-train low (LHTL, n=6). LHTH groups, were exposed to hypoxia for 4 weeks. LHTL, were exposed to 12 hours hypoxia and 12 hours normoxia a day for 4 week. Hypoxia is maintained by reducing 15% O2 level (8850 SUMMIT, Altitude Tech, Canada). The training protocol corresponded to 60-70 % of maximal exercise capacity by means of maximal exercise test. This test consisted of graded exercise on treadmill, with increments of 0.3 km/h for LHTH group,and 0.6 km/h LLTL and LHTL groups, every 3 min, starting with 0.3 km/h up to maximal intensity attained for each rat. Rats in the training groups ran on the rat treadmill (MAY-TME 9805, Commat, Ankara, Turkey) for 20-35 min a day, 4 day a week for 4 week. At the end of the experimental period, maximal exercise test was repeated at 2nd day of low altitude. For peak force and muscular fatigue, the electrical stimulation was administered with an intensity of 6-7 V and pulses of 2 msec duration. To induce a tetanic contraction, the frequency was raised from 0.2 to 60 Hz and kept there until the muscular force fell to 50% of its value at the onset of that particular contraction. Kruskal Wallis and Mann-Whitney U tests were used for the differences between groups, p values 0.05 accepted as statistically significant. Results and Conclusion: As a result of study, LLTL and LHTL groups peak force are more high than LL groups (p=0.004; p=0.0017) also there is a significant difference between LLTL and LHTH groups (p=0.017). The muscular fatigue values of LHTH is lower than LLTL and LHTL, but these values did not reach a significant difference. As a result of this study, LHTH group is more disadvantaged than other training groups.