__By Ron Kaspriske
Everyone has a favorite machine for their cardio workout, but not all cardio workouts are created equal. In an informal survey of some well-respected fitness experts, here are the top-five machines that will make your heart purr like a race-car engine:
1.Laddermill Ascender: As you might guess, this machine simulates the movement and muscle power required to climb a ladder. On a personal note, I only recently got a chance to try one and it was simply awesome. Within five minutes, I was gasping and my forearm muscles were on fire. It's not only No. 1 on the chart for what it can do for your body, but also because it's not motor driven. In other words, it's a quiet, eco-friendly, mean, green machine.
2.Versaclimber: See a pattern developing here? The Versaclimber also simulates ascending on a ladder. It's been on the market much longer than the Laddermill and will give you a terrific, total-body workout. There are many versions of this machine including one for rehab that comes with a seat. Your back, butt and arms will be ripped in no time.
3.Stairmill: If you've ever visited a friend at the top of a 12-floor walk-up in some old building, then you can appreciate the concept behind a stairmill. I know some might argue that taking the stairs is better, but it's not exactly healthy to be breathing the stale air inside a building's stairwell. Many companies make versions of this machine, but StairMaster's is my personal favorite. Note: A mill differs from the traditional step climber in that it looks like actual stairs and you can walk with a forward lean, which more closely simulates what you would do if walking uphill.
4.Rowing machine (pictured): There are many companies that make these, but I'm a big fan of the eco-friendly models such as Waterrower, which requires no electricity. Actual rowing is a great activity, but the machine also will help strengthen your legs, arms and back while improving your circulation and stamina.
5.Treadmill: This one might catch you by surprise because, on first take, treadmills seem pretty one-dimensional. But it's actually one of the only cardio machines that allow you to move laterally and backward. And if you change the belt's speed and incline, you can vary the workout even further. Jogging backward is great to help develop the muscles on the backside of your body (often ignored) and moving laterally helps train your all-important hip muscles.
Ron Kaspriske is the fitness editor of Golf Digest.
(Photo by Getty Images)