Mild mannered and reserved Clark Kent could enter a phone booth and come out as Superman. Any of Mr. Kent's inhibitions were swiftly cast aside and amazing strength and courage were displayed. (But why Superman could let bullets bounce off his chest and then duck when they threw the empty gun at him -- well, that remains a mystery.)

Many runners also experience a similar metamorphosis when race day arrives. A phone booth is not required -- rather we simply enter the port-a-john and come out as Racing Machine. No flying cape is necessary, nor is a large S emblazoned across our chest. However, give us a race number and a few safety pins, tie a computer race chip to our shoelace, point us in the direction of the Starting Line banner and all of a sudden we undergo a personality mutation.

Any timid, demure or restrained nature is cast aside and we become unabashed members in the Emancipation from Decorum Club. No longer do we feel somewhat unnerved about using a public restroom, as the world becomes our own little fire hydrant. Neither tree nor corner alley nor patch of bushes is safe from an overloaded bladder before or during a race. The world may be an oyster for some, but it also serves as a large lavatory for a racing runner.

We can go from our bland and color-coordinated conservative work attire to wearing every color in the Mercury Paint catalogue in our shorts alone. And who's going to carry a handkerchief or tissue along during a race? No way. Suddenly need to blow your nose a little -- we'll just turn to the side, make sure the landing pad is clear and give a little honk. The runner's shameless method of proboscis projection.

Your pre-race routine includes becoming Mr./Ms. Anti-Friction. You're a walking human lubricant as you fervently lather petroleum jelly on every single potential chafing area. Most significantly, you have no reservation about applying it to any usually-concealed body part in front of thousands of perfect strangers. Modesty, shmodesty.

Additionally, no run would be complete without a visit from some of our bodies' natural cacophony. It's the melody of the runner's short, sometimes rhythmic, and often spontaneous -- body sounds. We may try to successfully squelch a little burp at the board meeting, but now we feel equally triumphant if a belch reaches decibels of a sonic boom and we achieve trajectory levels of low-flying aircraft with our spit. And clearing our throat? We have no concern if we sound like a cat with a colossal toupee size of a hairball.

We also shed all pretenses with our loud gasps, grunts and pants. We shamelessly display wheezing toward the end of the race which sounds like a lactate overloaded and congested Tin Man from the Wizard of Oz trying to start a 1964 lawn mower -- with both having had no oil in more than 30 years.

We normally exhibit impeccable dining manners, but now we aggressively grab a cup of sports drink on the fly, gulp it down as quickly as possible as it dribbles and drools from our mouth as we then forcefully discard a crunched-up paper cup on the sidewalk. Post race refreshments serve as the catalyst for seeing how many bananas and bagels we can consume in the span of our best 800-meter time. We often burn more calories racing around the refreshment tables then we did during the run itself.

If we cross the finish line with a new PR, we deep-six any semblance of emotional restraint as we repetitively thrust our arms in the air and let out a Neanderthal scream of delight, which is followed by 47 consecutive resounding shouts of "Yes! Yes!"

Hours later, we've changed out of running clothes, showered and resumed our more-restrained personality. Until the next race. Until they give us another number to pin to our chest. Until we once again emerge as Racing Machine. Look out!

Excerpted by permission from "I Run, Therefore I Am--Nuts!" by Bob Schwartz. Copyright (c) 2001 by Human Kinetics Publishers, Inc. Available at bookstores, Amazon.com, www.humankinetics.com or 1-800-747-4457.