Elliptical machines are popular at gyms.
"It's easy on my knees, and it's just easy to work out with," one gym member said.
Ellipticals imitate the motion of running without the hard impact. Consumer Reports tested more than a dozen designed for home use. They cost anywhere from $800 to more than $3,000.
Testers designed an apparatus to measure how much force you need to move the pedals at various resistance levels.
"That's important because if a machine has a wide range of resistance levels, you can modify the intensity of your workout," said Peter Anzalone with Consumer Reports.
Testers also assessed the structural integrity of each machine. With a jack, they increased the force on the elliptical's pedal. And trained panelists evaluated the machines.
The $2,200 Endurance E400 was the lowest-rated elliptical tested.
"It just doesn't give a smooth ride," tester Linda Greene said.
The top-rated elliptical is the $3,100 Octane Fitness.
"This machine performed well in all our tests. It's built well, and it has a nice display that's easy to read," Anzalone said.
For far less, the Vision X30 Premier came in second. It costs $1,800.
"It's really easy to access and program your exercise sessions," Anzalone said.
But no matter which machine you buy, it's important to always try it out first.
Consumer Reports cautions that elliptical machines can be dangerous for children, so don't let them use them unsupervised. And a recent survey finds only 59 percent of machines are still regularly used a year after they were purchased.