Previous studies have shown that exercise of maximal intensity and 30-s duration (which corresponds approximately to the sprint time performed by the children during the high intensity training) requires essentially an anaerobic glycolysis contribution.’ Moreover, when several bouts of exercise are performed, an inhibition of glycogenolysis occurs at the third and fourth exercise bouts. Therefore, the muscle oxidative capacity is not solicited, and this can explain the moderate decrease of VTh, which would represent the muscle oxidative capacity. birth control yasmin
This assumption supports the findings of previous studies which have reported that a close correlation exists between VTh and the percentage of slow-twitch fibers. Moreover, it could be assumed that, above a training intensity which corresponds approximately to 85 percent of Vo2max, increasing the training load decreases the oxidative capacity of slow-twitch fibers. This land of training leads to a major problem because any decrease of VTh will induce an exaggerated hyperventilation at submaximal exercise intensities, which represents for the asthmatic children, a very bad long-term adaptation for the same reasons previously discussed.