Bolt's Bolt

In case you didn't have a working television over the weekend, Jamaican Usain Bolt is once again the fastest human being on the planet. The second fastest human being is also Usain Bolt, as he topped the world record in the 100 meter dash that was previously held by...himself.

When world records like these are beaten, it makes me wonder what the human limits are. Will we one day see a human sprint at 125 mph and finish the dash in less than 2 seconds? It seems impossible, or at least very, very unlikely, but there were naysayers who claimed ten seconds would never be beaten (Bolt's time, of 9.58 seconds, is the fastest, but most Olympic sprinters clock under 10 seconds). There were people who told Roger Bannister in 1954 that a 4 minute mile was impossible, and yet he did it, and now sub-4-minute times are normal. Olympic athletes run 4 minute miles now and afterward hardly seem winded. The marathon record now stands around 2 hours 4 minutes, which when divided by 26 and 7/32 miles means Haile Gebrselassie, the current record holder, ran just over 4 minute miles...for over 2 hours.

I'm not treading new ground when I ask these questions. Is the question now "will 9 seconds ever be broken" in the 100 meter dash?
Empirically, probably not. If you look at swimming, you see that records are broken quite often, but only by hundredths of seconds. Typically, records are broken along a logarithmic curve, i.e. more and more time passes between significant record changes, or conversely, the more frequently records are broken, the less significant they are.

Further, there are limits to the human body, simply because of mechanics. Bolt's sprint happened at about 23 miles per hour. At around 30 miles per hour, the forces required to pump your legs are so great you will tear the muscle right off the bone. At 45 miles per hour, the gravitational change as each leg swings is enough to break your bones. At much over the speed Bolt is running, you either cannot obtain enough friction in your foot to hold to the ground or you wear spikes, and the shear force of the spikes will dislocate or fracture your ankle.

Which, I humbly submit, helps define to us what humans are: not sprinters. Cheetahs can carry a speed of 65 mph over distances longer (but not much longer) than 100 meters, sailfish can reach similar speeds in water, and peregrine falcons can reach ridiculous speeds in the air. However, humans are one of the only creatures in all of Earth's history capable of running 26 miles, much less in two hours. Simply stated: humans are meant to jog.

There is a lot of evidence for this in physiology and anatomy: We have thin skin, covered in sweat glands (sweat glands are bizarre and rare in the animal kingdom), we have long, lanky legs with flexing knees, as opposed to extending knees like those of a stork. We have high-mounted heads with a large tendon in the back. The tendon allows us to keep our head stable as we jog or run, and is unique to humans in the primate family. Other animals with the tendon: horses and dogs, known distance runners. And metabolically, we're unique in our ability to stay in aerobic respiration during anything faster than a walk. Our joints are physiologically designed to actually strengthen during jogging, while running pounds microfractures into our bones faster than they can heal, and walking for too long actually damages the menisci in our knees.

It has been recently suggested that early humans employed a clever hunting tactic when chasing prey species: they'd run them to death. It is believed that early humans would fan out somewhat wide, and trot after a deer, or a bison, or whatever. The prey animal would bolt, and then stop and wait to see if it was followed. Soon, the humans are spotted again, and it bolts again, and so on and each time it is building up a little more lactic acid in it's sprinter muscles. Eventually, after a while, the animal overheats, goes into toxic shock, and calmly stands there while the humans walk up and kill it. This method of hunting is actually a popular winter hunting method for wolves, who can jog over the snow, while their prey, the heavy moose, must break through the snow, and quickly tires and (even in winter) overheats.

So as much as Bolt's record breaking run was thrilling, I feel we're nearing the end of sprint records. Perhaps a hundredth will get shaved off here, or there, but I'm fairly confident that humans just can't go much faster. What we can do, and I find very interesting, is go farther. Ultramarathons, 50 or 100 mile mega races often through rough terrain, are what impress me more. To me, sprinting isn't what we were built to do, so I don't really find it all that remarkable. Jogging, forever, is what got us here, and so I find those good at it so much more impressive.


_