Go ahead, climb the wall. Reach for a handle and pull yourself up, hand over hand, foot past foot.

And when you get to where you can't climb another inch, hop on down and do it again - this time by a different route using different handles.No, this wall climbing isn't the result of frayed nerves or a loss of control. On the contrary, as a sport it's fun. An outlet, for some.

And, said Steve Hyans, manager of the Rockreation Sport Climbing Center in Salt Lake City, it's not as difficult or as dangerous as many people might think.

Young kids do it, as soon as age five, and senior citizens climb, some as late as age 65.

Wall climbing is an offshoot of general mountain climbing, only it's done indoors, under controlled conditions and on a wall made to look like one giant wall in a retail store. There are hundreds of handles or holds attached to the wall, some very small, barely wide enough for fingernails to cling to, and some very large and secure feeling to the grip.

There are four businesses in Salt Lake City with climbing walls, one in Ogden and one in Provo, and many smaller walls in garages and basements.

Climbing walls are simply walls made to look like mountain cliffs. Attached to the wall are holds of infinite shape, size and difficulty. The holds are place in such a pattern that they become actual routes up the wall.

There in, said Dave Smith, specialty product coordinator for REI, is the challenge.

Calling on everything from balance to body control, climbers perform a ballet on the wall . . . reaching, stepping, holding, twisting, turning and, at times, even jumping from hold to hold.

"It is an opportunity for a person to climb in a controlled environment. They don't need to worry about temperatures or setting up ropes for the safety harness. There's already in place. There are routes for beginners and those for very experienced climbers," he added.

Wall climbs are all rated at 5, referencing vertical climbs where the leader places ropes for the protection of up-coming climbers. The number after signifies the difficulty.

REI's new wall, which was doubled from the size of the old one because of interest, runs from easy climbs of 5.0 to a extremely challenging overhanging arete rated at 5.14.

Rockreation's wall falls into about the same area with 75 percent of its climbing walls, more than 6,000 square feet, rated for beginner and intermediate climbers, and the remaining 25 percent setup for advanced climbers.

The things that attract people to the walls, said Hyans, "vary from the challenges of simply climbing to the excitement of being up there and holding on to the different skill levels wall climbing requires. It's all those things.

"It's funny, but the kids generally take to it more easily than adults. The first thing you've got to overcome is the fear of heights. Some of our walls go up 45 feet. Kids have no fear whatsoever. They go right up and don't stop to look down until they're at the top."

Wall climbing does not, as some people believe, take a lot of upper body muscles. In fact, women generally do better than men, said Hyans. They're muscle-to-weight ratio is better, and they tend to be more graceful in their climbing.

REI just opened its new Red Rock Mountain Climbing Structure on Saturday. Features include a pillar, a moderate layback route, a difficult hand-crack route and a moveable boulder that can increase or decrease difficulty.

It does not charge for its wall unless it is reserved by a group. Primarily, it is there for customers to use. It is open to climbing on Tuesdays, Thursdays and Saturdays.

Smith said the structure was designed and painted to resemble Utah rock - the limestone in American Fork Canyon, sandstone in southern Utah and quartsite in Big Cottonwood and Ogden.

Rockreation charges $14 for an adult and $9 for kids 11 and under. It also has a number of programs, including a beginner "Fight Gravity One," that includes two hours of instruction and a one-week membership for $30.

The Wasatch Front Rock Gym charges $8 for an adult day pass and $5 for kids 12 and under. It has 3,000 square feet of climbing wall that peak at around 30 feet. It also has a bouldering climb (without ropes) and a "Woody" or wooden wall for advanced climbers.

The Extreme Sport Center has a wall with five top-rope sections and 16 routes. Cost is $5.95 for two hours.