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Oct 1, 2009 10:49 pm US/Central
Good Question: Why Are Some People So Fast?
MINNEAPOLIS (WCCO) ―
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"I think a lot of the speed in a marathon has to do with how you're born, what your genetics is," said Dr. William Roberts, medical director for the Twin Cities Marathon.
CBS
When you watch an elite runner zip through a 26.2 mile marathon, it's either inspiring or depressing. Why are some people so much faster than others?
"I think a lot of the speed in a marathon comes with how you're born, what your genetics is," said Dr. William Roberts, medical director for the Twin Cities Marathon.
Dr. Roberts has worked with runners for more than 30 years.
"There's running form: how you look when you run, how you place your heel, foot and your stride length, and then there's: how do you do that in the most efficient manner?" he noted.
That measure is called running economy. It's a measure of how much oxygen you use over a certain distance. Some runners conserve oxygen and energy, running the same distance as others.
"Someone with the same genetics as an elite runner who doesn't train isn't able to do it as well ... because their heart hasn't been trained," said Roberts.
Researchers haven't figured out if there is one right way to run. Some studies have found that keeping a natural stride length is key. To run faster, runners can either extend their stride length or repeat their strides more quickly. Over-extending stride length seems to not be very effective, according to the research.
There is a right way to move your arms, however, according to Roberts.
"The arms need to be working to counter the force of the run. The usual is the cross body movement of the arms," said Roberts, demonstrating arms at the side but crossing the body at a slight diagonal.
According to Roberts, the marathon's medical team will watch runners to see if their arms start to droop, as that can be a signal that something's wrong.
While genetics help determine if a runner is slow or fast, it also determines whether a runner is good at sprints or distance.
"The fiber type is different," said Roberts. Some muscle fibers provide explosion for speed. A different type helps endurance.
"If you took an Olympic sprinter and distance person and put them side-by-side you'd see a tall, broad, heavily muscled sprinter, and usually a thin, shorter, leaner distance person," he said.
There are things runners can do to become faster, by losing weight and building up endurance. Coaches can help work on form. But going from fast to elite is something that can't normally be done without the right genetics, according to Roberts.
(© MMIX, CBS Broadcasting Inc. All Rights Reserved.)
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