Our living rooms are getting crowded.

Once only Jane Fonda entered our homes and showed us how to flex and stretch our way to good health, but now thousands of celebrities, models and fitness experts have exercise videos to their names.

In the little more than a decade since Fonda first put rather straightforward aerobics routines on tape, the fitness video market has become glutted with programs targeted toward people in all walks of life. That's why you'll now find in video catalogs and stores such diverse titles as "The Macarena Workout," "Hula for Health," "Hot Country Aerobics" and "Jamaica Me S'wet."

There are workouts geared for those sitting in chairs, driving in cars or attempting to improve their golf game. And you can work out to videos set to gospel music, classical music, dance tunes, disco and even nature sounds.

Even furry little Elmo, the Muppet of "Sesame Street" fame, has his own video gig. "Elmocize" is a 29-minute video aimed at showing your preschoolers how to "bend, stretch, twist and hop their way to feeling good."

Such diversity is not the only reason exercise videos have been so quickly snatched up by the viewing public.

"I think many people have decided they want to work out at home," says Linda Shelton, fitness editor for Shape magazine. The tapes can be popped into the VCR at any time of day, rain or shine. At an average retail price of $15, they're much cheaper than joining a fitness club. Mothers can exercise at home without hiring a sitter.

But when it comes to purchasing fitness videos, it is buyer beware, experts warn. Some employ moves that can result in injuries. Others have insufficient cool-down periods. And some fail to produce real results.

Even if a video is safe, however, the location where most fitness buffs watch the tape may pose dangers of its own. Many living room floors are not well-suited to high-impact aerobics because they do not provide sufficient cushioning. And exercising at home without an instructor's supervision could also result in injury if the moves are not followed correctly.

Here are some more tips:

-- Before buying an exercise tape, try renting it to make sure it suits you.

-- Ensure the video meets your needs. Does it provide strength training? A good aerobic workout? Is it fun?

-- Make sure the choreography is not too hard so you can follow the moves.

-- Ask yourself if you like the instructor on a given tape. Says Shelton, "It's like taking a class at the gym. You really do want to get a motivating quality."

-- Notice the technical value of the tape. Does the camera focus more on an instructor's face than on her feet?

-- For safety's sake, be sure to read the small print on the back of the video box. Pay special attention to the choreographer's credentials, whether he or she is a certified fitness instructor. "Don't assume that just because a celebrity is on the cover that this is going to be a bona-fide safe routine," Shelton says.

-- Look beyond the cover's claims. "If the cover says you too will look like this in three or four sessions a week, don't believe it. These are airbrushed images of contoured, siliconized human beings," Shelton says.

-- Assess whether an exercise video will keep you motivated. Or, after spending a full day in front of a computer terminal, is working out in front of a television the last thing on your mind? If you buy videos and think this is the thing that's going to get you in shape and don't end up watching them, realize they didn't do anything for you.