No pain, possible gain Mar 04 2014
Three years ago, Kayla Montgomery was diagnosed with multiple sclerosis. Faced with the prospect of being confined to a wheelchair someday, Montgomery, one of the slower runners on her high school cross country team, told her coach she was short on time and wanted to run faster. Now she's one of the fastest runners in the country and perhaps the MS has something to do with it.
Kayla Montgomery, 18, was found to have multiple sclerosis three years ago. Defying most logic, she has gone on to become one of the fastest young distance runners in the country -- one who cannot stay on her feet after crossing the finish line.
Because M.S. blocks nerve signals from Montgomery's legs to her brain, particularly as her body temperature increases, she can move at steady speeds that cause other runners pain she cannot sense, creating the peculiar circumstance in which the symptoms of a disease might confer an athletic advantage.
But intense exercise can also trigger weakness and instability; as Montgomery goes numb in races, she can continue moving forward as if on autopilot, but any disruption, like stopping, makes her lose control.
"When I finish, it feels like there's nothing underneath me," Montgomery said. "I start out feeling normal and then my legs gradually go numb. I've trained myself to think about other things while I race, to get through. But when I break the motion, I can't control them and I fall."
Researchers, however, have long noted a link between neurological disorders and athletic potential. In the late 1800's, the pioneering French doctor Philippe Tissie observed that phobias and epilepsy could be beneficial for athletic training. A few decades later, the German surgeon August Bier measured the spontaneous long jump of a mentally disturbed patient, noting that it compared favorably to the existing world record. These types of exertions seemed to defy the notion of built-in muscular limits and, Bier noted, were made possible by "powerful mental stimuli and the simultaneous elimination of inhibitions."
Questions about the muscle-centered model came up again in 1989 when Canadian researchers published the results of an experiment called Operation Everest II, in which athletes did heavy exercise in altitude chambers. The athletes reached exhaustion despite the fact that their lactic-acid concentrations remained comfortably low. Fatigue, it seemed, might be caused by something else.
In 1999, three physiologists from the University of Cape Town Medical School in South Africa took the next step. They worked a group of cyclists to exhaustion during a 62-mile laboratory ride and measured, via electrodes, the percentage of leg muscles they were using at the fatigue limit. If standard theories were true, they reasoned, the body should recruit more muscle fibers as it approached exhaustion -- a natural compensation for tired, weakening muscles.
Instead, the researchers observed the opposite result. As the riders approached complete fatigue, the percentage of active muscle fibers decreased, until they were using only about 30 percent. Even as the athletes felt they were giving their all, the reality was that more of their muscles were at rest. Was the brain purposely holding back the body?
"It was as if the brain was playing a trick on the body, to save it," says Timothy Noakes, head of the Cape Town group. "Which makes a lot of sense, if you think about it. In fatigue, it only feels like we're going to die. The actual physiological risks that fatigue represents are essentially trivial."