A bouncy, anti-gravity workout with the new AlterG treadmill

When I finished my first half-marathon last month, I experienced what it felt like to run on the ground for two hours. But what is it like to run in a gravity-reduced vacuum? When AlterG offered me the chance to demo their new "anti-gravity" treadmill, I couldn't resist. I jumped in my car and headed over to the gym at UCSF, down in the Mission Bay neighborhood of San Francisco.

A physical therapist named Chris gave me a rubber tube to wear over my running clothes. It looked like a cross between a wetsuit, a tire, and a tutu, and it had a giant zipper going across the top. He told me to step up onto the ramp and then zipped me into the giant rubber veil that covered what otherwise looked like a pretty ordinary treadmill.

The AlterG is no ordinary treadmill, though. It is a super fancy, super-expensive treadmill that isolates the lower body in a vacuum and literally takes off percentages of your body weight using technology developed by NASA. It's meant to help disabled, overweight, and injured people get a solid cardio workout without putting a strain on their limbs, but at this particular gym anybody can sign up to buy time on the machine in 30-minute increments. The AlterG uses air pressure to create the sensation of lost weight — the machine can reduce your body weight by up to 80%, making you feel like you're floating, flying, or bouncing on clouds.
By pushing arrow buttons on the treadmill screen, I was able to change my body weight percentage — air would blow into the vacuum that surrounded my legs, and the tutu-wetsuit became tighter, essentially lifting my body off the ground and making my legs float backwards into a naturally wider gait. It gave me a wedgie, and I could feel my thighs sweating from the tight seal, but none of that mattered. This was so much more fun than normal running! I ran on the AlterG for about fifteen minutes, happily romping through the clouds at a 7.5 min/mile, a near-impossible feat for the ordinary me. I felt like a gazelle.

I didn't realize just how much fun I was having in 20% gravity until my time was up. Chris deflated the air around my legs, unzipped me from the machine, and asked me to step down. As I lugged my now-impossibly heavy legs down from the treadmill ramp, I realized just how heavy I really was. My legs felt like elephants, and my spirits sunk so low that I wondered if I was suffering from a temporary depression.

So why can't all of us work out like this all the time if it's better for our bodies and more fun than real running? Maybe because the thing costs $24,500. And before the new version, the M300, was introduced last Monday, its predecessor cost $75,000. The New York Knicks and J-Lo have been known to work out on the AlterG, but it's unlikely to end up in my fitness room (what fitness room?) anytime soon. Let's not forget, our basic Bowflex costs about a grand, and we can all run for free outdoors.