Climbers started the movement. Forced indoors by weather or circumstances, they built an indoor wall and on it put a bunch of little bumps, some no more than a crack.
They practiced climbing techniques, strengthened fingertips and toes, and talked of climbing mountains and cliffs when the weather broke.
Then, for the very reasons climbers moved indoors, others followed. Today, indoor climbing walls are everywhere, and people of all ages and abilities are reaching for the edges, stepping on the incuts and showing daring by grabbing for the extreme holds.
All this, of course, indoors in air-conditioned comfort and under supervised safety procedures.
And, while indoor climbing still attracts the elite climbers, those reaching for the handholds now are climbers at every level of ability and age. And, in particular, the sport is attracting families.
According to Matt Nielson, manager of Utah's newest climbing gym, Momentum, "Parents are bringing their kids in and the entire family is climbing. I'm also seeing more women who actually want to climb rather than being here just to hang out with their boyfriends."
The story goes that indoor climbing on artificial structures started in England in 1964. People first climbed on rocks embedded in a wall.
The first indoor climbing gym in the United States surfaced around 1987 in Seattle. Climbers, hoping to keep their skills fresh on rainy, snowy days, fixed hand and foot holds on a wall and practiced climbing.
The first climbing center in Utah was also started by climbers and was designed more for bouldering or free climbing than for toprope climbing.
Momentum is not only the newest climbing gym in Utah but also the largest 20,000 square feet of climbing space, ranging from boulder fields to a 42-foot climbing wall. There are thousands of handholds of various sizes, shapes and purposes, and walls that offer climbers everything from beginning to expert routes.
There are also 13 cracks that are part of the climbing walls for those who are into climbing cracks. These routes are modeled after the cracks in the popular Indian Creek Canyon climbing area near Moab.
Bouldering, as the name suggests, involves free climbing large boulders, which in the case of the Momentum boulders, are man-made.
Bouldering is a branch of rock climbing that is rapidly growing.
Nielson said one reason is bouldering doesn't require a climbing partner "Although it's more fun climbing with a partner." It can be done with very limited equipment, mainly a pair of climbing shoes and a chalk bag.
"It's the least expensive form of climbing," he added. "Also, a climber doesn't need to know all about the knots or ropes or about anchor systems."
Bouldering also does not require ropes to belay climbers. Any slip generally results in a fall, which indoors means a short fall onto 10-inch padded mats.
As noted, climbing walls come in various heights and difficulties. When climbing indoors, there are anchored ropes attached to a harness worn by the climbers. The other end of the rope is held by a second person. In case the climber falls, the rope stays secure and the climber is held suspended in place.
The message instructors try to convey early on to new climbers is that even if they do let loose of the handholds, they need to relax, "you're not going to fall."
Each of the walls is dotted with handholds of different shapes, sizes and colors. On beginning routes, the holds are larger and easier to grasp and stand on. On more difficult routes, the holds are smaller, thinner and more difficult to reach.
Nielson said there is a full range of climbing routes, ranging from beginner to expert. The choice is up to the climber, "but everything is set up to allow a person to reach the top," he added.
There are, of course, good reasons people choose to climb indoors, aside from safety, weather and convenience.
On particularly hot days, outdoor climbing can be difficult, uncomfortable and not at all friendly to equipment.
Climbing shoes, for example, heated by the summer temperatures and hot rocks, can come apart. Also, sweaty hands make it difficult to hold onto narrow grips.
"It's also possible to get in a good workout in three to four hours indoors, where the same level of workout may take eight to 10 hours outdoors. It takes time to set up ropes and, if it's crowded, then you have to wait your turn," Nielson said.
It is also a fact that climbing provides both aerobic and anaerobic exercise. Constantly moving arms and legs offers aerobic advantages, and pushing up with legs and pulling with arms requires strength for anaerobic exercise.
As far as climbing technique, Nielson said one of the first lessons taught to beginners is to focus on legs and not arms.
"We tell people to use their arms as little as possible and the legs more than they think they should. The legs are stronger and used to carrying the body weight. You don't want to pull yourself up, but instead push yourself up with the legs. Do this and you can climb longer and better," he said.
Climbing fees depend on the particular gym. Basic fees at Momentum are $15 for an all-day pass for adults and $12 for children 12 and under. The center also offers private sessions for birthdays and company gatherings.Here in Utah, and in other states with inclement winter weather, indoor gyms make it possible to climb year-round.