AlterG® Anti-Gravity Treadmill Inova Physical Therapy Center - Fairfax/Sports Medicine has the revolutionary AlterG® Anti-Gravity Treadmill. The Anti-gravity Treadmill is great for runners, rehabilitation, and can help you conquer your mobility impairments. AlterG adds a new dimension to the customized treatment and training plans we provide our patients. See how the Anti-Gravity Treadmill can benefit you in the video.