"If I put Lance Armstrong in a wrestling contest at the Olympics, I doubt that he would do very well," said William Kraemer, a professor of kinesiology at the University of Connecticut in Storrs.
According to the University of Texas's Coyle, there are certain physiological traits that a person must have to excel in an endurance sport such as long-distance cycling.
"To be the best on the planet, you don't have to be superhuman in any of these components, but you can't be weak in any of them," Coyle said.
In addition to a high VO2 max, Coyle's components include low lactic acid levels, and Armstrong has the lowest levels Coyle has ever seen.
When people reach exhaustion, their muscles build up acid, which causes the muscles to stop contracting. But Armstrong's muscles produce about half as much acid as the average person's muscles do when they get fatigued. This allows him to recover much faster than other people.
"You can see when Armstrong races, he can attack better than anybody," Coyle said. "He makes a break, then backs off and then breaks again, wearing [the others] down until they can't recover, and then he just takes off."
Slow-Twitch Muscle Fibers
Though Armstrong had a genetic head start in some areas, he did not have an advantage in one area: muscle efficiency.
Our muscles work much like the cylinders in a car. When air is mixed with gasoline in the cylinders of a car, a small explosion occurs and energy is released. Likewise, the muscles burn the food we eat, they produce raw chemical energy.
The movement of an engine's pistons allows most cars to capture 5 to 8 percent of that raw energy. In our bodies little chemical motors known as muscle fibers allow us to capture 18 to 23 percent of the energy.
At 21, Armstrong had a distinctly average 21 percent muscle-efficiency rate. Seven years later that rate had increased to 23 percent, a huge leap.
Researchers suggest there may be two ways to improve efficiency through training.
One way is to train for higher maximum capacityin other words, to increase the upper limit of performance (as a sprinter might). Another way is to train for greater submaximal capacityto expend less energy for sustained performance (as a marathoner might).
Armstrong did both.
"We don't know exactly what accounted for Armstrong's muscular-efficiency change," Coyle said. But he suspects that Armstrong was able to convert fast-twitch muscle fibers to slow-twitch muscle fibers.
While fast-twitch fibers are good for sprinting, for example, slow-twitch muscle fibers are twice as efficient and are good for endurance sports.
With more slow-twitch muscle fibers, and increased muscle power, Armstrong is able to move his legs faster. As a result, his pedaling rate has gone up from 85 revolutions per minute to 105.
During Coyle's study, Armstrong was diagnosed with cancer and underwent surgery and chemotherapy. Remarkably, Armstrong showed no ill effects from the cancer upon his recovery.
It has been suggested that Armstrong lost weight from the cancer, making him a leaner (and better) cyclist. But Armstrong's weight eight months after his chemotherapy was the same as before his cancer treatment, according to Coyle.
However, surviving cancer almost certainly made Armstrong a stronger athlete mentally. Sports scientists agree that Armstrong is one of the most disciplined and focused athletes in the world.
"[He] is on top of the cycling world because of the combination and interaction of his genetic endowment, years of incredible training, competitive experience, and obsessive drive to achieve and persevere," said Phillip B. Sparling, a professor of applied physiology at the Georgia Institute of Technology in Atlanta.
It's a combination that's made Armstrong a rarity among men, but still just a man. "Most athletes are happy to perpetuate the myth of the superhuman," Coyle said. "But now that Lance is retiring, I think he'd be the first one to admit that he's not superhuman at all."
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