Last November, I was on my way to the New York City marathon when I got word that my father had two clots on his brain and needed emergency surgery. My family urged me to go ahead and run anyway.

It was to have been my first marathon since I gave up running years ago, and my first high-profile race since writing my book "Born to Run.'' I had trained to run it barefoot, and even announced my plans to the world in an article in The New York Times.

"It's what your father would want," my mother said, encouraging me to stay in New York. But it's not what my father would do. So the day before the race, I turned around and headed home.

During my father's recovery, I teetered on that ledge we all encounter when the curtain drops on our main event before it ever goes up. Without a challenge ahead or a beat-down still smarting behind, there's no urgency to snap back into serious training. You're off schedule and like it that way, letting one week of occasional runs drift into three, working out by feel instead of formula - until you realize you feel lousy and have barely worked out at all.

Just about the only time I pushed myself was every other week or so, when I met a band of local trail runners who have an absurd mail-carrier ethic when it comes to snow, rain and gloom of night. No matter how dark or cold, they never cancel, bobbing along by headlamp through ice storms, face-whipping branches and far too uncommon self-doubt. It's not the punishment they love, I eventually realized; it's the goofy thrill of banding together in the face of slippery awfulness.

While many of them had finisher's medals from Boston and New York and Chicago, their stories were never about marquee races or fast times. Instead they talked about Mrs. Smith's Challenge and Megatransect and Super Hike, backyard events with no more prestige than a Sunday softball game. They never crowed about nailing qualifiers or lucking out in lotteries, but good lord could they go on about tailgating with microbrews and Old Bay burgers while cheering their friends to the finish.

Before long, these war stories made me forget my disappointment over missing New York and rekindled my first long-distance love: an event that not only gave birth to modern endurance sports, but could be their redemption. It's called the "Fat Ass."

These events are trail races governed by three rules: no fees, no awards, no whining. Distances are typically 50 kilometers or 50 miles, but vary according to a race director's whims or ability to borrow his buddy's GPS device. There are no lotteries, no expos, no qualifying times, no triple-digit entry fees subsidizing multimillion-dollar "running clubs." No one will urinate on you from the upper span of the Verrazano Bridge, and you won't shiver for hours in a corral before the starting gun. Everyone charges off as equals, Braveheart-style.

On the other hand, you get what you pay for. Aid stations are as makeshift as the course measurements. Some are spartan: friends sharing a jug of water and family-size M&M's. Others are bizarre. Two volunteers at a Maryland race had their hearts set on serving deep-fried turkey, but surrendered to the impossibility of carrying enough poultry and oil into the woods for 300 runners. They settled instead for handing out fistfuls of fresh-cooked French fries.

My debut in the series was in 2006, a 50K (about 31 miles) in a lonely Delaware forest on a freezing January morning. Since it was my first race on trails and my first of any kind after a six-year layoff, I decided to stick tight to a seasoned vet named Hunt Bartine so I wouldn't be stranded if I couldn't follow the trail or handle the distance. My plan was working nicely, until Mr. Bartine suddenly stopped and started cursing. Somehow, he'd wandered off a trail which he, personally, had marked the week before. It took a good 10 minutes of thrashing through brambles before we got back on course. Five hours later, I popped out of the trees and crossed the finish line. The winners were still there, ladling out steaming cups of vegetable barley soup to the runners-up.

The format spontaneously burst into existence, by some weird synchronicity, in three different places in the same year. In February 1978, a few American sailors in Hawaii decided to swim 2.4 miles off Waikiki Beach on Oahu, then bike 112 miles around the island and run all 26.2 miles of the Honolulu Marathon course to see who among them was the toughest - the true iron man. Meanwhile, a gang of Colorado slackers were busy ritualizing an act of vengeance; previously, they'd pushed and pedaled their clunky, one-speed town bikes all 38 miles from Crested Butte to Aspen to settle the score with some rich Aspeners who'd parked their motorcycles in front of a favorite Crested Butte bar. In 1978, just for the fun of it, the Butte-heads declared the Aspen ride an annual event.

And in San Francisco, a runner who couldn't find a race decided to fake one. Joe Oakes needed a 50-mile qualifying time to apply for the Western States 100. He tried to sign up for a 50-mile relay, but solo runners weren't permitted. So Mr. Oakes entered seven times under seven different spellings of his name. Team Oakes pulled it off, and from identity fraud a movement was born.

"There is so much greed and so much money in sports these days," Mr. Oakes later explained to Ultrarunning magazine. To rebel against ever-escalating entry fees, he created the "Recover From the Holidays Fat Ass 50-Mile Run."

"There is not a nickel involved in any of these events," Mr. Oakes has said. "You just show up and run. It's very simple."

Soon, these races were popping up in Philadelphia, Toronto and England, gradually spreading as far as Siberia and South Africa. The rules have never changed and the name has stuck, albeit translated into regional languages.

Since those freewheeling founding days, big money has invaded mountain biking, marathoning and the Ironman. Gone is the era when a buck could get you into the New York City marathon. Last year, even the Leadville 100 - one of the original, old-school, mining-town, backcountry ultra series - was taken over by corporate ownership and franchised.

But off in the woods, Fat Asses are flourishing.

"Let's stop paying high prices for commercial cookie-cutter road races and let's start exploring!" the founders of the New York Trail and Ultrarunning Club declared in December. Within 80 days, that grumble of a mission statement has attracted more than 200 members. The appeal isn't strictly about cash; it's about connection. These races are hometown and homemade. It's not Hollywood; it's your high school play.

That's the choice I was faced with when, a few months ago, I was offered complimentary entry into the Boston Marathon, one of most storied, exclusive races in the world. I thought about it - but not for long. Instead of 26.2 miles, I'll be paying back my missed New York marathon with 20 percent interest by lining up for the 31-mile HAT Run along the Susquehanna River near my home in Pennsylvania. I won't be barefoot, since it's a rocky trail, but I'll be able to wear the same homemade huaraches that my friend "Barefoot Ted" McDonald gave me when I paced him at Leadville.

In a way, I never did resume training; I've just been spending more and more time playing in the woods. The prospect of another gigantic "cookie-cutter" left me cold, but a six-hour Braveheart re-enactment was a different story. The HAT Run costs $65 to enter, but every cent comes back to the runners in gift bags, park permits and food. (The current race directors are the same two guys who once tried to fry turkeys,  and they still serve smoking-hot "UltraFries" midrace.)

"We're filling up faster than we want," said Tim Gavin, an organizer of the run. "Long-timers aren't used to this kind of rush for spots."

Fortunately, Mr. Gavin's spill-off has created its own throwback movement. Every March, the Buzzards running club holds a free-for-all marathon near Harrisburg, Pa. The Buzzards synchronize the race date each year with the HAT crew so that anyone who doesn't get into HAT, or doesn't want to pay, has a free alternative.

And down in Mexico, the semi-mythic loner called Caballo Blanco continues to resist offers of corporate sponsorship for his Copper Canyon Ultramarathon with the Tarahumara Indians, the event I chronicled in my book. Caballo messaged me last week, after more than 300 Tarahumara and international runners turned up for his most recent race. "Together, we all created peace in a small town at the bottom of nowhere,'' he wrote. "Nowhere but beauty. What more is there?"

Editor's Note: You can find a few FAT ASS events in this area.  The Trail Dawgs out of Delaware offer several a year.