All the dangling harnesses and tethers look like the tangled strings of a marionette. They stretch 20 feet overhead, their ends hovering over a thick blue mat like the ones that once cushioned your fall in grade-school gym class. A tall gray box sits in the middle of the room with what looks to be a conveyor belt running up its side.
Most people don’t get to see the machine this closely. Those who do must hand over their shoes so they can be brushed free of potentially damaging dirt and dust before stepping across the threshold of the gray-colored laboratory. Most visitors only get a peek from the windows set high up the walls on the far side of the lab.
There are only two other machines like this one, but neither is as evolved. The hope is that the work happening here, inside Cleveland’s NASA Glenn Research Center, will allow scientists to determine how to better stave off the loss of bone density and strength in astronauts who spend long stretches of time in space and lead to the creation of lighter exercise equipment that can be stowed on future spacecraft for zero-gravity workouts.
Why bother to create a treadmill that stands upright when the world is already populated with perfectly good horizontal ones? The main reason is that NASA Glenn’s Enhanced Zero Gravity Locomotion Simulator can mimic the weightlessness astronauts experience in space. In short, it’s what a space workout would feel like.
“There’s no other simulator here on Earth that will do that,” explains Gail Perusek, project manager for NASA Glenn’s Exercise Countermeasures Project.
The zero-gravity senation is made possible by the vertical positioning of the treadmill, which requires subjects to use it suspended parallel to the ground. A harness pulls the runner toward the machine, but what really gives the treadmill a bouncy feel are four discs underneath it that emit powerful jets of air that cause the running platform to float much like the way a plastic puck floats on an air hockey table.
“It’s very comfortable, sort of a buoyant feeling,” says Christopher Sheehan, a project manager for a NASA contractor. He has used the treadmill a number of times because his six-and-a-half-foot frame makes him a prime test subject for a taller body type. “You kind of feel like you’re floating on one of those little rafts in a pool.”
This machine’s grandfather, the original Zero Gravity Locomotion Simulator, is housed at the Cleveland Clinic. It was the result of collaboration between the Clinic and Penn State University in 2004.
Shortly after, NASA Glenn engineers created the Standalone Zero Gravity Locomotion Simulator and sent it to the University of Texas, where the Johnson Space Center uses it for studies.
But, unlike its two predecessors, NASA Glenn’s third incarnation of the vertical treadmill can also re-create the gravitational pull of other planets.
The various levels of gravity are mimicked by tilting the metal structure surrounding the treadmill to different angles, creating the feeling of running on Mars, which has less than half Earth’s gravity, or the Moon, which has just one-sixth of Earth’s gravity.
The running itself, however, takes some getting used to. The difference in weight distribution created by the machine puts more pressure on muscles in the lower body. The result is a treadmill that gives a powerful lower body workout.
“There’s nothing really painful about it,” says Sheehan. “I’ve been in these simulators for hours on end while we’ve been working through issues. It’s actually really relaxing to be honest with you — after you get over the shin splints.”