"Hearst Magazines and Yahoo may earn commission or revenue on some items through these links." Most gyms have an elliptical machine. And chances are, someone's on it—and using it incorrectly. The ...

Treadmills and ellipticals are two extremely popular machines you can use at the gym or buy for your own home. And there's a reason for that: Both get your heart rate up, work your lower-body muscles, ...