"One possible mechanism for increased efficiency is that (Armstrong) increased his percentage of type I muscle fibers, (indeed) we predict that he might have increased his percentage of type I muscle fibers from 60% to 80%," the report said. "Interestingly, this magnitude of increase…is remarkably similar to our predictions made in 1991 based on cross-sectional observations of competitive cyclists."
This change in muscle type may account for the apparent ease with which Armstrong seems to be pedaling, albeit at a high cycling cadence.
Whereas the lab tests were held constant at 85 revolutions per minute (rpm) for comparison purposes, Armstrong's "freely chosen cycling cadence during time trial races of 30- to 60-minute duration increased progressively during this y-year period from about 85-95 rpm to about 105-110 rpm. This increase in freely chosen rpm when cycling at high intensity is indeed consistent with increase in type I muscle fibers because cyclists with a higher percentage of type I fibers choose a higher pedaling cadence when exercising at high power outputs," the report said. "Although this may initially seem paradoxical, higher cycling cadence serves to both bring muscle fiber contraction velocity closer to that of maximum power and reduce the muscle and pedaling force required for each cycling stroke," it noted.
As body matures, it gets "smarter"
Coyle said increased muscle efficiency means that "for the same amount of cardiovascular and lung stress Armstrong is producing 8% more power, and yet producing less heat. These results have shown us how to improve already highly trained athletes by aiming at efficiency, which is a muscle phenomenon. But it's also nice to know," he added, "that as you get older that your body becomes wiser in how it does its job and less wasteful in energy usage."
Coyle added later: "There's no doubt that Armstrong started with a strong genetic makeup, but he maximized his abilitie
Source:American Physiological Society