We've all seen videos of the Apollo astronauts doing what came to be called the "moon walk". The bounce-hop-skip maneuver they invented to navigate across the Moon's surface at 1/6th gravity, really looked like fun. Now, using technology originally developed by NASA you can do the moon walk here on Earth at normal gravity and more importantly, for post-surgery or post-injury rehab, as well as super-human speed racing during athletic training.
Some call it the anti-gravity machine, or the weightless workout system. However, Alter-G, the Silicon Valley company that developed it as a product, calls it the "G-Trainer". They initially marketed it as a unique athletic training system that allowed effective exercise to be accomplished during recovery from injuries. Now they have FDA approval for its use as a medical rehab device too, based on benefits in that area already experienced by its users.
The G-Trainer consists of a programmable treadmill inside an inflatable air-tight bag that encloses a person's lower body and is pressurized. It maintains a controlled positive pressure on the lower body which is flexibly sealed at the waist within the semi-rigid bag. The air pressure pushes the body upwards to counter gravity pushing it downwards so a person can comfortably walk, trot or run full-out at a user-selectable "effective body weight". The system is not actually anti-gravity, it's counter-gravity. The pressure can counter up to 80% of the body weight while the treadmill supports speed levels up to 18 mph.
According to Alter-G the benefits of the G-Trainer are that it "enables individuals who have been weakened or impaired by illness, disuse, injury or surgery to improve mobility and health, and recover more effectively by overcoming the challenges that limit their movement". By unloading body weight during exercise, the therapeutic and training advantages of normal and even hyper-normal mobility can be received without the pain of supporting 100% of body weight. The benefits of controlled, appropriate-level loads for promoting healing and conditioning in cardiovascular, nervous, muscle, bone and connective tissues are well known and are the basis for getting people out of bed and moving at the earliest possible time. Alberto Salazar, a world-class marathon runner and Director of the Nike Oregon Project for running research, considers the G-Trainer to be a breakthrough. He notes, "by reducing my athletes' effective body weight, they've increased their training volume by 25%, without increased risk of injury and this has enabled them to compete at their highest levels ever."
NASA's prototype was called the Lower Body Positive Pressure (LBPP) device - no brand name awards received - but that's exactly what it was. I was fortunate to be invited by Dr. Alan Hargens to try out an early version of LBPP a few years ago at the NASA Ames Research Center. The experience was quite amazing and suggested what moon walking might be like. It felt like I had instantly lost weight and I pranced along the treadmill very lightly.
NASA initially experimented with volunteer subjects lying on their backs while Lower Body Negative Pressure (LBNP) was used to simulate the cardiovascular effects from blood shifts that occur when you stand upright, but are absent in spaceflight during Earth orbit. After several weeks of this "bedrest" that produces many of the effects of spaceflight here on Earth, they found that periodic LBNP helped keep the cardiovascular system and blood volume almost normal. This convinced NASA, post-Apollo, to include a LBNP device on the Skylab space missions to use for biomedical research during the almost 90 day period that astronauts lived in space. LBNP on Skylab demonstrated its protective effect to spaceflight cardiovascular "deconditioning" including the fainting often seen when astronauts returned to Earth's gravity and tried to stand up. The addition of LBPP was part of NASA's overall research program in exercise applications to counter spaceflight effects. Several of the potential benefits of LBPP for rehabilitation and sports medicine applications were anticipated. What was likely not envisioned by NASA were applications for athletic injury prevention and performance enhancement.
With its FDA approval in hand, Alter-G is in the process of participating in more formal studies to evaluate the medical benefits of the G-Trainer to complement the accumulating informal evidence. For example, Walter Reed Army Medical Hospital reports, "A below the knee amputee in his second week of learning how to walk with his prosthetic was able to get into the G-Trainer on his own without any difficulty. His body language and facial expressions said it all. He had found a way to teach himself to walk without pain, without the fear of falling, and without being dependent on someone else to hold him up. The transition from walking to running and jogging is a difficult process for amputees and can result in a lot of falling -not with the G-Trainer. The G-Trainer holds patients in place, allowing for a quicker recovery. The usefulness of the G-Trainer as training tool for this transition appears to be obvious."
The potential medical rehab applications for this system are many and could include improved mobility for patients after stroke, joint replacement, and similar conditions where muscle weakness and gait problems would benefit from safe, low-level exercise with a reduced body weight in a supportive system. The Center for Disease Control reports that each year an estimated one-third of older adults fall with the likelihood increasing with age. It has been shown that exercise can be a key element in lowering this risk and the G-Trainer may make a real contribution in supporting active aging, something which will benefit us all.