Running on one can give you all the comforts of home, but it can also be hard on your knees.
But now a new state of the art treadmill, takes the pain away.
The makers of the antigravity treadmill technology say it was originally developed by NASA to train astronauts.
It uses air pressure to lift you up, so you can feel like you're up to 80 percent lighter.
"It adjusts according to your body weight level so if you were 150 pounds you get in and I want to reduce it by 10 % you're now a 135 pounds and you're running at what feels like wow I just lost 15 pounds," says Lindsay Dettbarn.
Dettbarn, a personal trainer for Equinox gyms, shows us how it works. First you have to put on the tight shorts with what looks like a tutu on top
Once it inflates, you can control the air pressure to give you more or less of a lift.
With less impact on the joints, it allows patients and injured athletes to train or recover from surgery with less pain.
Tina Lundgren has achilles tendonitis and used the Alter G to get ready for the New York City Triathlon.
"I was able to prepare for the race by running on the machine & only running maybe once a week outside," she said.
The antigravity treadmill is also available at physical therapy centers in the tri-state areas.
To see where this treadmill is available in our area, go to, LINK: http://www.alter-g.com/product/find-an-alterg