for National Geographic News
In cycling, triathlons, and other races, the leader of the pack may not be out ahead in terms of innate talent.
The "bunching" that often occurs in such events gives some racers an advantage that masks their individual ability. As a result, the person who crosses the finish line first isn't necessarily the most physically and mentally fit competitor in the race.
Many bicycle racers travel in packs so they can share the effects of wind resistance and pick up speed. The race may be won or lost on the final sprint.
And in orienteering, in which participants use maps and compasses to navigate from point to point, runners who see someone up ahead may push to catch up without the help of the map.
Graeme Ackland, a physicist at the University of Edinburgh in Scotland, noticed this pack behavior in orienteering events in Scotland and in cycling and triathlon events during the 2000 Olympic Games in Sydney, Australia. What causes it, he wondered, and could the effect be minimized?
"I noticed the packs forming and started wondering if there was any scientific way to describe it," he said.
Ackland and his colleague David Butler have developed a computer model to show how packs form. They say the model, described in the September 13 issue of Nature, might help race organizers figure out how to stagger the start of an event to avoid pack formation and increase the chances that the most skilled competitor wins.
The model is based on race conditions such as the number of competitors, the length of the course, the time intervals between the competitors' start, and individual speed.
But the most significant factor in determining whether packs are formed, the study showed, was the racers' ability to catch up with contenders up aheada variable the researchers describe as the "boost factor."
In cycling, Ackland said, the boost factor is "the knowledge that if you can catch up, you will get a real aerodynamic boost. Pack formation benefits everyone and they [competitors] know it."
"When racing alone, it is easy for concentration to waver and [for a competitor] to slow without realizing it," he added. "In a pack, the other competitors maintaining their speed should prevent this."
According to the computer model, if more than 13 percent of the competitors can see and catch up with the competitor ahead of them, all the competitors will rapidly cluster in pack formation.
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