Interesting.
Overview G-TrainerTM Anti-Gravity TreadmillsTM are changing the weight of the world. G-Trainers enable people to improve mobility and health, recover from injury and surgery more effectively, overcome medical challenges that limit movement, and enhance physical performance. Whether you're an elite athlete who can't afford bench time or an individual whose daily life doesn't have time for sitting still, G-Trainers are designed for everyone.
Link: Alter G - Zero Gravity Cross Trainer