Elliptical trainers, like this one from NordicTrack, offer a great cardiovascular workout and (for better or worse) create no impact on joints. (Courtesy NordicTrack)
I'm going to buy my sister an exercise machine for her birthday and it's a toss up between an elliptical trainer and a treadmill. Which do you believe would give her the better workout?
— Erica Luddington Halifax, Nova Scotia
You're a nice sister! There's little denying the massive popularity of elliptical trainers. You walk into a gym these days and it seems like everyone's moving his or her legs through an egg shaped trajectory. The machines are designed to minimize the impact forces of running while maintaining the cardio workout of being on a treadmill.
When you walk, your impact forces might be two times your body weight on a leg, while running can notch that up by a figure of 12. Impact forces are even higher for people carrying extra weight, of course. Repetitive exposure to high impact forces is considered the cause of many joint injuries, which is why the idea came along to help people work out without their feet ever catching air.
In that regard, elliptical trainers succeed. Studies show that elliptical trainers provide the same cardio workout as running, in terms of heart rate and oxygen consumption, while reducing the impact forces to that of walking. But impact forces are not all bad. You need them to increase your bone density (your body responds to the absorbing of shock by telling your bones to build new cells), and if you don't keep your bones dense when you are young, hormone loss when you are older will put you at greater risk of getting bent-over and shrunken.
But there's another issue here: Every time you absorb an impact you require your muscles to stabilize your joints, and practicing this makes you stronger at absorbing forces. Thus, impact forces are a particular conundrum, as getting too many may wear down your knees, but getting too few will mean you risk losing your eccentric (speed-slowing) strength, which in theory will make your joints more susceptible to injury. Confused? Then my work here is done.
Elliptical trainers are particularly good for anyone who has bad joints or is starting a training program carrying a few extra pounds. Which would be all of us. Treadmills, on the other hand, ask your body to get better at an activity it may actually be called upon to execute in the real world: running. And running entails absorbing the forces that come with living on planet Earth. But who's to say you have to be so—I don't know—reasonable. Definitely try both machines out. Then buy whichever one seems fun enough that your very lucky sister will want to use it all the time.
Paul Scott is not a personal trainer but he plays one in magazines. Being as how standards for the profession vary so much, and how he reads far more than a writer can expect to have to read about a subject like training, he thinks that is OK. A health and fitness writer for Outside for about six years now, he is the author of Outside's National Magazine Award-winning article series "The Shape of Your Life," which he is currently trying to fashion into a book of some sort. We all want to cover our butts, so here Paul will try to cover his: Nothing said here should overrule the advice of your doctor. Use your judgment at all times, both in the gym and out. Look both ways before crossing the street. And if you have reason to wonder, ask your doctor if it's OK before starting any workout program. We all want you to live a long, healthy life.
You're a nice sister! There's little denying the massive popularity of elliptical trainers. You walk into a gym these days and it seems like everyone's moving his or her legs through an egg shaped trajectory. The machines are designed to minimize the impact forces of running while maintaining the cardio workout of being on a treadmill.
