Just how fast can a human run the 100-meter sprint?

Whenever the world record in the 100-meter sprint is broken, disputes erupt in the sports science community over the limits of human performance.

Scientists who considered 9.50 seconds as the limit in the race changed their projections after Usain Bolt of Jamaica set world records in succession at the 2008 Beijing Olympics (9.69) and the 2009 World Athletic Championships (9.58) in Berlin.

Bolt has said a 100 meters in 9.40 seconds is possible. what is fastest a human can run?

A sprint race entails two major running methods. One is the stride run, in which a runner takes bigger steps and reduces the number of cycle of steps (pitch). The other is a method in which the runner takes smaller steps and increases the number of cycle of steps.

A famous runner who used the pitch method is Ben Johnson of Canada. He won the 100 meters with a time of 9.79 seconds at the 1988 Seoul Olympics but was stripped of his record due to doping violation.

He took only 46 steps from the starting point to the end, translating into 4.7 steps per second.

The runner known to have taken the widest stride is Christophe Lemaitre of France, the first Caucasian to run the 100 meters under 10 seconds. He runs the 100 meters with 40.5 steps and takes bigger steps than Bolt (who takes 41 to 41.5 steps).

This means the Frenchman advances 2.47 meters per step. This is a hypothetical situation, but if the two runners only combine their advantages, they can run 11.6 meters (2.47 meters x 4.7) per second.

This means that theoretically, a human can run 100 meters in 8.62 seconds. Even including the time required for starting, the lab time will be within nine seconds.

Of course, strides and pitches are relative terms and continuing to improve them all the time is tough. Usually, the taller the runner, the bigger steps he or she will take but the ability to supplement the slowing pace of steps is also needed.

Thus far, Bolt is the runner who has most ideally combined the two running methods.

Another important factor is the time required for starting. When he set the world record in 2009, Bolt had a starting time of 0.146 seconds, slower than 0.104 seconds set by Tim Montgomery of the U.S. at the 2002 Paris Grand Prix finals. Had Bolt started as fast as Montgomery, the Jamaican`s world record could have been 9.54 seconds.

So if the starting time is less than one-tenth of a second, this is considered a foul because the theoretical limit that a human can start moving the body is a tenth of a second. A U.S. research team, however, recently claimed that human response time to start could be as little as 0.085 seconds.

This means that if the rules change, the record could be lowered by another 0.015 seconds. So Bolt’s record will be broken someday.

why@donga.com