Whenever you walk into a new gym, one space inevitably catches the eye: the main floor, filled with cardio machines of all kinds, rows and rows of ’em. And whether you’re there for a chill yoga class ...

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, ...