AlterG, Inc. is an American medical device company founded in 2005 by Sean Whalen in Fremont, California. The company makes mobility enhancement products for physical therapy and athletic training. The first product, the Anti-Gravity Treadmill, now includes a product line including the M/F320, Via 400 and 400X, and Pro 200 and 500. In 2013 the company acquired Tibion Corporation and added the Bionic Leg to its list of products. Charles Remsberg is CEO.