THURSDAY, Aug. 14, 2008 (HealthDay News) -- Endurance-running fans awaiting the upcoming marathons at the 2008 Summer Olympics in Beijing may no doubt be wondering how the runners can complete the grueling 26.2-mile event, especially when air pollution has been a concern.
In fact, marathon great Haile Gebrselassie, who reportedly has exercise-induced asthma, opted out of the marathon event, citing China's air pollution as the deciding factor.
Air pollution aside, a team of researchers has now found clues to how runners keep on going to cross that finish line.
Throughout a long-distance race, the runner's heart rate increases in a very controlled manner, and appears to be scaled to the race distance, said study author Carl Foster, a professor of exercise and sport science at the University of Wisconsin-LaCrosse. The report is published in the August issue of Public Library of Science.
Foster and his colleagues evaluated 211 male middle- and long-distance runners, who were, on average, 32 years old and had various running abilities.
Foster's team evaluated the heart rate responses of the running during competitions ranging from 5 kilometers to 100 kilometers by using lab tests and heart rate recordings. All were serious competitors, although they were not of elite caliber.
What happened? The runners were found to actively manage the increasing strain on their body in anticipation of getting to the finish line -- which requires constant reassessment of their fatigue levels.
The heart rate increased in a consistent pattern during the events, they found, and seems to be scaled proportionally to the distance of the event. As the authors write: "Athletes are continually in a dialogue or negotiation with themselves, assessing how fatigued they feel."
Then they adjust the pace to be sure muscle fatigue doesn't get out of control.
The pattern of heart rate response during an event was very similar in all athletes, even though their running performance and times varied. This suggests, the authors write, that "adept runners are faster due to their underlying physiological capacity rather than because they put more relative effort into their competition."
"When you prepare and go out and run a 10 K, the person who wins is probably not running harder," Foster said. "He just has a better, bigger motor."
The report is interesting and the results make sense, said Dr. Gerard Varlotta, director of sports rehabilitation at New York University and Rusk Institute, in New York City.
"To me what they are saying is there is a protective system built in that doesn't allow us to overuse our muscles," he said, and that speaks to the value of training. "When you do something repetitive, the body knows how to prevent injury," he said.
The feedback a runner receives during a race -- slow down, speed up, keep the status quo -- Varlotta added, "is a learned pattern of behavior, and the muscles get regulated subconsciously by the brain."
The finding that the runners' heart rates increased in a very controlled way is a positive one, Foster said. "It gives us hope we aren't going to kill ourselves."
To learn more about running, visit the American Council on Exercise.