Burned out on stair climbing, she wanted a different exercise. She found it. Scaling a mountain at a gym may not be the real thing, but it works for her.

I have no desire to climb mountains. None. While I’ve done my share of challenging hikes, scaling rocky peaks while tethered to a rope is not my idea of a good time.

But for the longest time I’ve wanted to try one of these climbing gyms, where faux walls substitute for the real thing, and you can learn the basics without worrying about plunging 50 feet and turning your internal organs into Cream of Wheat.

A friend links the desire to climb to our primate ancestry, but for me it’s about StairMaster burnout and having to stare at those annoying little red dots charting my workout day after day while slowly going insane.

Climbing gyms have become extremely popular in recent years with both experienced climbers and novices. Chalk it up to greater recognition of the sport, as well as gym rats looking for the next big thrill. It’s also become popular with families, who can practice the sport together.

I enrolled in a beginning class at Rockreation, a climbing gym in Costa Mesa. (There’s also one in West Los Angeles. See end of story.) The four climbers in the three-hour class consisted of a young couple, a girl about 12 and me.

After getting into our soft, flexible climbing shoes (provided by the gym), our instructor, Mike Mason, a 15-year climbing veteran, patiently took us through techniques and safety measures. We learned how to put on the harness, tie knots, take up slack on the rope, use the belay device to make sure the climber doesn’t fall, and give formal commands. The buddy system allows for a climber and a belayer--the latter staying on the ground to hold and lower the climber.

Finally, it was time to ascend. The walls are studded with thousands of odd-shaped grips and footholds, some barely an inch wide. After safety-checking each other’s rigs, my partner, the 12-year-old, scampered up the 25-foot wall so fast I barely had time to take up the slack in the rope. When she reached the top, I lowered her down without dropping her--a major accomplishment--and she landed gracefully on the bouncy rubber flooring. She climbed once more, and then it was my turn.

I got about halfway up and froze, suddenly realizing how far I was off the ground and wondering what I was doing up here. It was the same feeling I had when I was 8 and attempted to conquer the high-diving board: sheer panic, followed by an urge to back down, then thinking what a supreme idiot I’d look like if I did. So I kept on until I finally reached the top, then lowered to the ground. It was an exhilarating rush.

We scaled other walls that posed different logistical problems, and Mason led us across a traversing wall to practice our technique, with emphasis on footwork. He also demonstrated how to use our bodies to maximize efficiency and minimize exhaustion.

I began to appreciate how much climbing is a mental as well as physical challenge--certainly more than the predictable, boring StairMaster.

The three hours flew by, yet I felt I had learned an enormous amount.

Will I ever climb the real thing? It’s still not on the to-do list. But I can’t wait to get back on that wall.

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Rockreation, 1300 Logan Ave., Costa Mesa, (714) 556-7625; and 11866 LaGrange Ave., Los Angeles, (310) 207-7199. Beginning classes are $35-$40; other classes, private training, day passes and memberships are available.