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The Limits of Human Speed
 
 
 

Usain Bolt’s record-breaking performance at last year’s Beijng Olympics has generated intense interest in a timeless question: “How fast can humans run?” For perspective, Bolt officially ran the 100m in 9.69 seconds and the 200m in 19.30 seconds. The previous 200m mark had been set by Michael Johnson and stood for 12 years, since the 1996 Atlanta Games. Bolt is the first to win both sprint events since Carl Lewis in 1984, and the first to set world records in both. He broke his own world record in the 100m event and officially broke the 9.7 second mark. So this begs the question, “How long before humans break the 9.6 second mark?”

 

It was popularly believed that no human would ever break the 4 minute mark in the 1 mile run a little over half a century ago. Then, in 1954 Roger Bannister ran the distance in 3 minutes 59.5 seconds. Jesse Owens set a world record in 1936 in Berlin at the 100m event and shattered the previous record by more than a tenth of a second. Records are now broken in small increments of hundredths of a second and may soon require the measurement of thousandths. Isn’t it crazy to think that Owens’ time of 10.3 seconds is considered “on par” for junior level athletes today? In order to understand how these drastic improvements have occurred, one must examine the contributing factors to such speed. First and foremost, technological and scientific advancements have improved training methods and nutrition. Secondly, tracks have been improved and facilitate increased performance. Additionally, the lure of endorsement money has surely attracted many more athletes to compete than ever before. But are there other factors?

 

Recent literature speculates that elite runners have higher distribution ratios of fast twitch to slow twitch muscle fibers. Some researchers are even claiming that “super-fast twitch” fibers exist in the muscles of elite runners. Some of these bold claims are not yet scientifically based. Muscle biopsy studies have not been able to histochemically find even pure type-II muscle fibers in humans, let alone “super-fast twitch” fibers.

 

What about biomechanical advantages? Some experts claim that Usain Bolt’s height (6 foot 5 inches) is a disadvantage as it decreases the ratio of force to bodyweight that he is capable of generating, also citing that he is unusually tall for a gold medalist in sprint events. Bolt is considered to have a subpar explosiveness from a dead stop. Others claim that any negative effect his height may present is countered and perhaps outweighed by the increased stride length he gains from his height. Bolt only needed 41 steps to cover the 100m while the average for his competitors was 47 steps. Ed Coyle at the University of Texas's Human Performance Laboratory had this to say about Bolt, “He overcomes his average start and just doesn't slow down, as others do, in the last 30 to 40 meters. He's able to relax and coordinate his longer legs.”

 

In general terms, the average man can run about 15 mph for short periods. In 1996, Michael Johnson was clocked at an average speed of 23.15 mph over the 200m. Bolt hit an average speed of 23.09 mph in his 100m run. Peak speed record holder Donovan Bailey ran 27.07 mph during his then-world record 100m run at the Atlanta games. “No one can really know exactly how fast a human may be able to run,” says Dennis Bramble, professor of biology at the University of Utah. “Due to the fact that we only have a relatively short period of timed sprints recorded,” Peter Weyand, an expert in biomechanics at Southern Methodist University stated, “we have no way of knowing if humans might not have been even faster centuries or millennia ago.” Add Bramble, “Modern sprinters seem to be operating close to the limits of the human body. Still, when someone who is not built like a classic sprinter smashes the world record while making it look easy, maybe all bets should be off.”



http://www.independent.co.uk/extras/big-question/the-big-question-as-the-100m-world-record-falls-again-how-much-faster-can-humans-run-838899.html

http://www.time.com/time/world/article/0,8599,1834355,00.html

http://www.time.com/time/health/article/0,8599,1835420,00.html?xid=newsletter-daily

http://physiologyonline.physiology.org/cgi/content/abstract/13/6/261