Slapped Silly on the Slopes : * Bumps and bruises are a given for any adult who tries learning the youth- driven sport of snow boarding. But a few secrets will make it easier.

Mike and Don try to figure it out on their own. With rented snowboards underfoot, they grab a chairlift to the mid-heights of Mammoth Mountain and begin their descent. Twenty minutes later, sore and exhausted, they tumble to the bottom. “Nightmare” is the word they use to describe the experience.

Now they’re taking a lesson, which is where I join in. Unlike these two law students--whose names have been changed to protect their egos--I have been warned about learning to snowboard on my own. This is what everyone says: You can teach yourself to board in one day, but it will be a hellish day of bumps and bruises.

No problem for a 14-year-old. Snowboarding is, after all, a sport of the young with its snow slang and rock ‘n’ roll fashions, its ultra-baggy grunge with dangling jester beanies and big gloves. And there are the wild acrobatics. Inverted aerials. Riding fakie. Grabbing mute. But Mike and Don aren’t teen-agers. At this point, they’d settle for survival.

As for me, I’m 32 and I had enough trouble putting on my snowboard boots, which mysteriously feature laces on the inside and outside. Like many aspects of the sport, it is difficult to explain.

Bruce, the instructor who shows up for our beginner’s lesson, smiles and nods. Snowboarding is a little easier, he says, if you learn a few secrets.

Secret No. 1: Beginners look spastic.

The lesson begins on flat ground. My front leg is strapped to my board. My back leg remains free to provide push. Learning to walk in this way, I stumble and slip, arms waggling. Mike and Don suffer a likewise fate.

“Don’t worry,” Bruce assures us, smiling. He smiles a lot. “You’re doing fine.”

Next he teaches us to fall, curling into a ball and keeping our fists clenched to prevent broken wrists. The technique comes in handy as we wobble through a half-dozen practice slides. Secret No. 2: The trick to snowboarding involves a delicate blend of balance, shifting hips and twisting shoulders.

As I said, it’s difficult to explain. We must lean perilously over the nose of our boards. The effort is made more harrowing by the fact that our feet are locked into place. Wherever the board goes, we go. And vice versa.

When Bruce demonstrates, he looks surfer-cool with arms outstretched, tilting his body at supple angles against the force of gravity. When we try, Don collides with Mike and nearly wrecks his knee.

Yet, minutes later, the four of us are riding the chairlift.

“Perfect day for learning,” Bruce says. “It’s warm so the snow will be softer when you fall.”

He surfs cleanly off the lift while we struggle to stay upright. After such a shaky start, we strap our back feet onto our boards. It’s time to go downhill.

Secret No. 3: Your butt gets as cold as an ice cube.

That’s because you spend a good deal of time lying on the snow, struggling to get up.

Our first slide-tumble down the bunny hill is pure slapstick, with every twist and spill imaginable. I shout. Mike mumbles. Don slaps his hat against the snow in frustration. At least the frozen ground produces a numbness that allows us to ignore multiple contusions that might otherwise send us to a soft chair in the lodge.

At the bottom of the hill, we encounter another beginner, a young woman sitting near the lift.

“We all have the same look,” she says. “Like we’ve been beaten.”

Mike tells her that his right buttock is particularly sore. She complains about her left side. My pain is equally distributed. We curse the madman who invented this sport--Sherman Poppen of Muskegon, Mich.

According to the people at Transworld Snowboarding magazine, Poppen developed a crude precursor to the snowboard in 1965. His “snurfer” was fashioned of wood with a rope attached to the nose. Riders held on for dear life as they sailed downhill. Poppen sold a million of these contraptions over the course of 15 years.

Today’s snowboards look high-tech by comparison. Their wooden cores are encased in sheets of aluminum or plastic and coated with fiberglass or Kevlar fabric. The edges are capped with metal for carving turns. Gone is the nose rope. And the boards are specialized, some stiff and narrow for high-speed slaloms, others wide and flexible for the kind of brazen acrobatics that make the sport look deadly.

Secret No. 4: Snowboarding is no more dangerous than skiing.

That’s according to an Australian study cited in a recent issue of Health magazine.

I chant this, a mantra, throughout my first bumbling day. But another statistic interrupts. Snowboarding is a young man’s pursuit. Fran Richards of Transworld Snowboarding says that among the estimated 1.8 million boarders nationwide, the vast majority are under 20. Such youth explains the sport’s reputation for obnoxious devotees.

“We’ve taken all the 17-year-olds who were jerks on skis and we’ve put them on snowboards,” Richards says.

Plenty of obnoxious skiers remain on the slopes, of course. And as the first generation of snowboarders matures, the sport has earned respect for its gracefully carved turns and balletic aerials, maneuvers learned through years of sometimes bruising experimentation.

“You guys can do that stuff, too,” Bruce tells us at the lesson’s end. “Just keep at it.”

Mike nods. Stubbornness has got the best of him as he vows to return with his board the following morning. Don is already shuffling toward the lodge.

Secret No. 5: Those who snowboard and ski say snowboarding is harder to learn at first but easier to improve at thereafter.

“Once you’re over the first-day hump, you can become an intermediate much more rapidly,” Richards says. “That’s why the sport has taken off.”

So I, too, venture out a second day, allowing a wave of enthusiasm to mask the pain of battered muscles.

On my first run, tempting fate and the laws of physics, I use scant experience to surf fast across the snow and end up taking a hard fall. My legs twist in inhuman ways. My sunglasses fly through the air. My girlfriend, following on skis, scans the hillside for a medic.

But I get up.

There is something to this sport, something beyond the repetitious humiliation and self-flagellation, something that keeps me going. And by midmorning, I’m negotiating the intermediate slopes in a style that is upright, if not pretty. Even better, my butt stays warm.

I am surviving. I am snowboarding. I know a few secrets.