CLEVELAND -- Elliptical exercisers are one of the hottest kinds of machines at health clubs, and millions of people are buying them for their homes, too.

In Thursday night's Consumer Alert, On Your Side Troubleshooter Chris Caswell put the machines to the test.

Elliptical exercisers are low-impact machines, combining the benefits of a stair climber with a cross-country ski machine. You pedal in flattened circles, and you can add an upper-body workout by moving the handlebars back and forth.

"On the elliptical, you don't have the pounding that you do on (your knees) when you run," said Tom Mutchler of Consumer Reports. "It doesn't put any pressure on the knees. It's non-impact, so it doesn't hurt your knees or hurt any part of your body, and you get a good workout."

The elliptical exercisers at health clubs are bigger, smoother, more solid and far more expensive than ones you'd buy to use at home.

Consumer Reports tested four machines, ranging in price from $500 to $1,000. Right from the start, some were harder to use than others.

"It's real easy to get on this machine, you just step on it from the back," Mutchler said. "On the other hand, some people find a machine like this awkward, because you have to step over it, like you're mounting a horse."

A problem with another machine is that if you prefer to just hold on, the handles that move can hit your arms. And it's not very stable.

The Fitness Quest Eclipse 5000 can actually move across the floor when you exercise vigorously.

In the end, testers found that the best of the four was from Reebok, the Elliptical Cross-Trainer 6808. It costs $500.

It provides a good home workout, especially for someone who's already in good shape.

Fitness experts said that it's a good idea for beginning exercisers to start off slowly on an elliptical trainer to avoid overexertion. People should also check with their physicians before starting any exercise program.