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Thoughts on Anti-Gravity Treadmills

Posted Mar 14 2010 5:57am
Hi Doug,

I continue to use your site to educate myself and my therapists about strengthening joints, thanks for all you do. I am a hand therapist but am having a high demand for knee joint therapy also so have contracted a PT to begin providing some of your techniques. Our patients love the tailgate exercise. I have a question, I know you previously had a similar device that it is no longer available, do you have any experience with the Alter G treadmill?




Thanks for the question Rob and glad to hear your patients have discovered tailgating.

The Alter-G Treadmill combines anti-gravity technology with a treadmill to allow partial weight bearing while walking or running. The user wears a pair of neoprene shorts that zip into a shroud attached to the treadmill. The shroud fills with air which provides buoyancy.

I spent some time with the device in 2008 while at a convention in Chicago. As with all machines or tools, there are pros and cons. Here's my list:


  • All in one design. There is one interface, on the treadmill, for the anti-gravity machine and the treadmill. This makes it easy for a patient or therapist to use the device and control the amount of lift and treadmill speed.
  • No harness. Having designed the very first anti-gravity device for running, we used a harness system. No question that it was the weakest link in the design. At loads over about 40-50% body weight, the compression on the chest wall was often too uncomfortable. Fitting the harness was a skill and clients had to be well educated about what to expect. Alter-G uses neoprene shorts so the trunk and upper body are unencumbered.
  • Treadmill. At the time I used the machine, Alter-G's treadmill was made by Woodway - one of the premier treadmill manufacturers. Their treadmills are super smooth and quiet.
  • Unloading levels from 20% to 80% body weight. When I used the machine, the adjustments from one level of unloading to another was simple and in 1% increments.


  • Uni-directional motion. Once you're zipped into the shroud, you can only move straight ahead. You cannot turn sideways or run backwards at will (you can run backwards if you have the treadmill version that runs in both directions or if you get out and zip back in facing backwards). And although your trunk and upper body are free to move, the pelvis and lower body feel constrained especially at higher levels of unloading. The Newton (and the ZUNI before that) allowed 360 degrees of motion so a client could move from forward to backward to sideways to develop agility, coordination and to stress the body through different angles. For example, my clients will often jog forward for 2-3 minutes, turn sideways and perform a slide-shuffle, then spin backwards and retro-jog or skip, spin to the other side and then turn forward. The Alter-G reduces the effect of gravity but is not a movement training device like the Newton.
  • Neoprene shorts. Alter-G makes this seem simple but, in my experience, it wasn't. The sales rep had me slip on the elastic shorts (and they have what looks like a small skirt with a zipper on the top which is how you sip into the shroud) on over a pair of athletic / training shorts. Not very comfortable. The elastic shorts scrunched up my shorts and as the amount of lift increased, the pressure in the groin and lower abdomen was uncomfortable. I tolerated 50% body weight for a couple of minutes then asked him to bring it back down to lower levels.
  • Proximity to the controls. Once in the unit, the control panel is very close to you. In fact, so close that I had to alter the way I held my arms while running which felt awkward. 

Your options for anti-gravity treadmill work are the Alter-G, Pneumex, and Biodex (LiteGait also is on the market but is not an athletic application). Alter-G is well designed and packaged. it looks and feels like something from NASA. It's an integrated system. But, it's also nearly three times the cost of the competition.


UPDATE: New entry on my shoulder recovery for Day #3 .

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