Fit Test Drive: AlterG Anti-Gravity Treadmill

When I found out I was getting to try the AlterG "anti-gravity" treadmill developed by NASA -- I think I told everyone I knew. Several times. The AlterG works by pumping air into a chamber that surrounds your body from the waist down. This increases the air pressure and that, in turn, lifts you up so that your feet feel less of your weight as you walk or run. Bring the pressure up enough and it's almost like walking in space. Pretty cool, right?

If you're in decent shape, and are just looking for a standard cardio, muscle-building session, there's not a ton of payoff to this contraption. The more body weight you carry when you exercise, the more burn and benefit you get, so removing weight without some purpose actually makes your workout less effective. However, if you've had a back or leg injury -- reducing your body's impact on the ground can alleviate that hurt. This means you can keep yourself in shape and slowly build back strength in a safe and non-painful way. (Indeed, the AlterG is being used in hospitals to help spinal cord injury patients retrain their bodies for movement.)

Additionally, if you're an athlete training for an endurance race like a marathon or triathlon, not only does the machine reduce the likelihood of stress-related injury, you can also use it to increase your speed and build up your non-dominant muscles. I found the reason for this fascinating: When we're responsible for less body weight, it's easier to loosen up and extend our stride, which increases the range and distribution of muscles we use. This, in turn, will translate to better performance back in the "real world." (Interestingly, the product's press materials say that overweight people can also benefit; it protects joints from weight-related stress, they may be able to work out for longer intervals.)

Although the AlterG has become standard practice for numerous NBA, NFL, and college sports teams, not to mention hospitals such as Walter Reed -- it's not exactly standard gym fare. Luckily, I was able to track one down at Manhattan's Fusion Physical Therapy and Sports Wellness PC center. Gavin, the personal trainer on duty, did an excellent job of not making me feel quite as ridiculous as I looked in what I'll refer to as my "anti-gravity gear." Move over Nike, because this gym outfit includes a pair of shorts resembling the bottom of a scuba diving outfit with a big, zippered disk surrounding your waist. The disk part acts as like a lid to the anti-gravity chamber.

We started out by measuring my weight, so the machine would know how to adjust itself as we reduced pressure. I then began walking. Gradually Gavin reduced the impact. It's a difficult feeling to describe, but imagine yourself slowly getting lighter and lighter, like you're a balloon being inflated. As this happens, you find you're able to walk faster, and feel less burdened.

I'd have been impressed with the show if it ended here, but then Gavin gave me my, "let's see what this baby can do" moment. Wow. He brought me down to where I was only relying on 60 percent of my weight and then left me to run for a bit. The best description I can think of for how it felt was of what it must be like to channel your five-year-old self, running around with a really concentrated center of gravity and very little weight to hold you back. You just -- well -- go.

Pluses: If you have an injury or are trying to build up speed, this is a tough concept to beat. Plus, I really can't think of the last time I've been so smitten with a machine. It reminded me why running is fun, and--in that sense--it served as a great motivator.

Minuses: Chances are, you're not going to stumble across the AlterG at your local gym anytime soon (although a cheaper version is hitting the market, ringing in at $24,500 versus $75,000 for the traditional model). I'd say there's an additional willpower factor here: With an elliptical or treadmill, you're responsible for increasing impact from your baseline. Here, you're able to decrease it. This is, of course, what makes the tool useful and effective, but also tempting to just play around with.

Takeaway: Unless you're rehabbing or training for something specific (in which case it's got a very clear and innovative use), this isn't a real necessity. But if you've got access to one -- definitely take this opportunity to experiment with your weight and running pace.

Learn more: AlterG website, Fusion Physical Therapy & Sports Wellness PT, AlterG on YouTube

If you like the idea of feeling weightless, you might want to think about some aquatic workouts.