This scenario, in which slow pedaling pulls the glycogen out of fast-twitch muscle cells, may sound paradoxical but it isn't; after all, slow pedaling rates are linked with high gears and elevated muscle forces, while fast cadences are associated with low gears and easy muscle contractions.
Since fast-twitch fibers are more powerful than slow-twitch cells, the fast-twitch fibers swing into action at slow cadences, when high muscular forces are needed to move the bicycle along rapidly.
On the other hand, "fast" pedaling rates of 80 to 100 rpm are not too hot for the slow-twitch cells to handle. Slow-twitch cells can contract 80 to 100 times per minute and can easily cope with the forces required to pedal in low gear.
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Another possible paradox in the Wisconsin/Wyoming research was that fast pedaling led to greater fat oxidation, even though maximal fat burning is usually linked with slow-paced efforts.
Basically, the higher fat degradation at 100 rpm occurred because the slow-twitch cells handled the fast-paced, low-force contractions. Slow-twitch fibers are much better fat-burners than their fast-twitch neighbors.
Fortunately, there's a bottom line to all this: During training and competition, cyclists should attempt to use fast pedaling rates of 80 to 85 rpm, both on the flat and on inclines.
Compared to slower cadences, the higher pedaling speeds are more economical and burn more fat during exercise. Ultimately, the high pedaling rates also preserve greater amounts of glycogen in fast-twitch muscle fibers, leading to more explosive "kicks" to the finish line in closing moments of races. (European Journal of Applied Physiology, 1992)
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