With arms akimbo, bent knees, scraped knees, padded knees, smiles, gasps, frowns, hips lurching forward or asses behind, new creatures are invading Cambridge-the rollerskaters.

Most of them are hilarious, like a young couple skating together for the first time, the woman trying desperately to be graceful in her short shorts and her boyfriend trying to stay in control--while enjoying the view. Equally amusing are an older couple trying fruitlessly to act young again but having a great time, and racing tots who look ready to fall off their skates.

Gary Ramus, owner of Roller Power, said yesterday his business has been booming since he opened five weeks ago. He said he had enjoyed skating last year in California so much he decided to open a store in Massachusetts: "Boston and Cambridge were ready for something new, a new form of exercise, a new way of getting high." He added that while the mechanics of roller wheels and bearings are related to those of skateboards, the sport itself is completely different. Skateboarding appeals more to young daredevils, but everyone can enjoy rollerskating. Since most people skate as children, they are not afraid to get back on skates as adults, Ramus said.

Outdoor rollerskating also profits from the summer weather, whereas ice skating is restricted to cold rinks or even more frigid ponds. A rollerskater can enjoy the sun and the freedom of the streets, or he can skate at night--when the roads are all deserted.

Richard Reilly, an employee at Roller Power, added that skating over the cobblestones is like a zen art--you concentrate on spreading the vibrations throughout your entire body and let yourself go. Skaters use more muscles than swimmers, Reilly added.

Linda Chapnick, owner of the Rolling Stoned, said her business has been racing this summer. She said she got interested in rollerskating last year in California, too, when she and her husband became fascinated by skaters' expressions. Skilled skaters were completely absorbed in their sport while the others were simply fooling around and having a great time. Chapnick said the simplicity and the wholesomeness of skating is appealing--it is truly American, good exercise and a lot more fun than jogging. Her customers range from children to professionals, she said. One of Chapnick's customers, a young internist from Philadelphia, asked her where he could disco rollerskate in Boston, she said. To her surprise, he proved his skill by skating gracefully, backwards, up the hill behind her store.

Carol Monica, owner of The Games People Play, decided just yesterday to try skating with her niece, Monica Karpowish, she said. "I haven't skated in 28 years," she added, "but I skated a lot when I was little and I thought it would all come back." It must have, because she had no much fun she plans to skate everyday for exercise.

Margaret Streeter '79, a former figure ice skater, said yesterday that she thinks the rollerskating fad is great, although she is concerned about the danger from falling on rough pavement or dodging speeding cars. But she added that because of the energy crunch skating is a great idea: "Instead of getting in your car just put on your skates and roll to the store."

It sure beats walking.