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The Physiology Of Speed

Posted by Dan Peterson Aug 29, 2009

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Usain Bolt, the triple Olympic gold medal sprinter from Jamaica, predicted last week that he could break his own world record of 9.69 seconds in the 100 meter sprint with a time as low as 9.54 seconds.  (8/15 update: he came very close running a 9.58 at the World Championships in Berlin.)

 

He claimed his coach told him its possible, so he believes him. His coach, Glen Mills, may have just finished reading some new research coming out of Duke University that showed sprinters and swimmers who are taller, heavier but more slender are the ones breaking world records.

 

At first glance, it may not make sense that bigger athletes would be faster. However, Jordan Charles, a recent engineering grad at Duke, plotted all of the world record holders in the 100 meter sprint and the 100 meter swim since 1900 against their height, weight and a measurement he called "slenderness."

 

World record sprinters have gained an average of 6.4 inches in height since 1900, while champion swimmers have shot up 4.5 inches, compared to the mere mortal average height gain of 1.9 inches.

During the same time, about 7/10 of a second have been shaved off of the 100-meter sprint while over 14 seconds have come off the 100-meter swim record.

 

What's going on

Charles applied the "[constructal theory | http://www.constructal.org/]" he learned from his mentor Adrian Bejan, a mechanical engineering professor at Duke, that describes how objects move through their environment.

 

"Anything that moves, or anything that flows, must evolve so that it flows more and more easily," Bejan said. "Nature wants to find a smoother path, to flow more easily, to find a path with less resistance," he said. "The animal design never gets there, but it tries to be the least imperfect that it can be."

 

Their research is reported in the current online edition of the Journal of Experimental Biology.

 

For locomotion, a human needs to overcome two forces, gravity and friction. First, an athlete would need to lift his foot off the ground or keep his body at the water line without sinking. Second, air resistance for the sprinter and water resistance for the swimmer will limit speed.

 

So, the first step is actually weight lifting, which a bigger, stronger athlete will excel at. The second step is to move through the space with the least friction, which emphasizes the new slenderness factor.

 

By comparing height with a calculated "width" of the athlete, slenderness is a measurement of mass spread out over a long frame. The athlete that can build on more muscle mass over a aerodynamic frame will have the advantage.

 

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The numbers

In swimming, legendary Hawaiian champion Duke Kahanamoku set the world record in 1912 with a time of 61.6 seconds with a calculated slenderness of 7.88. Some 96 years later, Eamon Sullivan lowered the world mark to 47.05 seconds at a slenderness factor of 8.29.

 

As the athletes’ slenderness factor has risen over the years, the winning times have dropped.  In 1929, Eddie Tolan's world-record 100 meter sprint of 10.4 seconds was achieved with a slenderness factor of 7.61. When Usain Bolt ran 9.69 seconds in the 2008 Olympics, his slenderness was also 8.29 while also being the tallest champion in history at 6-feet 5-inches.

 

“The trends revealed by our analysis suggest that speed records will continue to be dominated by heavier and taller athletes,” said Charles. “We believe that this is due to the constructal rules of animal locomotion and not the contemporary increase in the average size of humans.”

 

So, how fast did the original Olympians run? Charles used an anthropology finding for Greek and Roman body mass and plugged it into his formula.

 

“In antiquity, body weights were roughly 70 percent of what they are today,” Charles said. “Using our theory, a 100-meter dash that is won in 13 seconds would have taken about 14 seconds back then.”

Bolt puts his prediction to the test next month at the track and field world championships in Berlin. One of his main competitors is Asafa Powell, the previous world record holder, who is shorter and has a slenderness factor of 7.85. My money is on the Lightning Bolt.

 

Please read more sports science articles at Sports Are 80 Percent Mental.

450 Views 0 Comments Permalink Tags: olympics, sports_science, track_and_field, usain_bolt

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For any guy who has endured more than thirty minutes on a road bicycle seat, there is usually some concern over the strange numbness that occurs in places that should not go numb. Well, a new study has some good and bad news.

 

Spanish researchers have found that active male cyclists have lower quality sperm to the point of infertility risk. Among other things, they blame the painful "function over form" design of the wedge bicycle seat.

 

The good news is that unless you're training to be in the next Tour de France with Lance Armstrong, your time on the saddle shouldn't do any long-term damage.

 

A team led by professor Diana Vaamonde, from the University of Cordoba Medical School, tracked the workout regimen of 15 Spanish triathletes, with an average age of 33 who had been training for at least eight years, while also monitoring their sperm morphology.




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For those in the test group that covered more than 180 miles per week on their bikes, the percentage of normal looking sperm dropped from a group average of 10 percent to 4 percent, a rate where infertility problems begin. Increased swimming or running did not affect sperm quality.

 

"We found a statistically adverse correlation between sperm morphology and the volume of cycling training undertaken per week," Vaamonde said. "We believe that all the factors inherent in this sports activity, especially with regards to the cycling part, may affect sperm quality," she added. "Moreover, we think that normal physiological homeostasis – the body’s ability to regulate its own environment – may become irreversibly altered, therefore resulting in complex anomalies."

 

Vaamonde cited three possible reasons for the results: the increased heat during exercise, the friction and pressure against the seat causing microtrauma on the testes, and the overall rigor of intense exercise.

 

The study was released last week in Amsterdam at the annual conference of the European Society of Human Reproduction and Embryology (ESHRE).

 

The Spanish researchers were following up on research from 2002 that showed similar results for mountain bikers. In that study, Austrian researcher Ferdinand Frauscher tested 40 active (two hours per day) mountain bikers with 30 non-bikers. He found that the bikers had about half the sperm count of the non-bikers. Frauscher explained (as only a medical doctor can) the possible reasons: "The exact causes for the decreased sperm motility are unclear. We believe that repeated mechanical trauma to the testicles results in some degree of vascular damage, and may thereby cause a reduction in sperm motility." Ouch.

 

For casual bike riders, the risk is still quite low. Allan Pacey, senior lecturer in andrology at the University of Sheffield, told BBC News, "It is important to stress that even if the association between cycling and poor sperm morphology is correct, men training for triathlons are spending much more time in the saddle than the average social cycler or someone who might cycle to and from work."

 

For those that are still not okay with the "saddle sores," there are always the anatomically correct seats and the padded biker shorts, not to mention recumbent bikes. Beyond that, maybe a nice jog would be better.

 

Please read more sports science articles at Sports Are 80 Percent Mental!

599 Views 0 Comments Permalink Tags: cycling, triathlon, tour_de_france, lance_armstrong, sports_science
Dan Peterson

Dan Peterson

Member since: Oct 1, 2007

A Look Inside the Mind of the Athlete - You can find a mix of sport science, cognitive science, coaching and performance stories here as I focus on the "thinking" side of sports. My "home" is at http://blog.80percentmental.com. Thanks for stopping by!

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