Those of us who are slow or reluctant runners or walkers might soon be able to slip on a lightweight, lower-body exoskeleton and up the speed and ease of our exercise, according to several new studies examining the effects of these high-tech robotic devices Personal, or wearable, exoskeletons, usually amalgamated from motors, cables, straps, springs and ingenuity, can shoulder a substantial portion of the work when we walk or run, the new studies show, potentially allowing us to move much faster or farther. They can even harvest energy from the movement — almost enough to power a cellphone.
But the latest exoskeleton research also raises provocative questions about what we want from exercise and whether making it easier necessarily makes it better.
Exoskeletons have been staples of science fiction for eons, enabling fictional soldiers, cops, everymen and Avengers to outgun, out-sprint and outlive their nemeses. In these stories, exoskeletons tend to be full-body, armored, stylish and indestructible.
Real world exoskeletons under development at most human-mobility labs today are none of those things. Some modern exoskeletons encase much of the body with the goal of helping people paralyzed by illness or spinal injury to stand and walk. But most are abbreviated devices, centered around either the legs or upper body. Some include motors; others are self powered, usually by springs; and some, known as exosuits, are made of soft, pliable materials that resemble clothing. All provide assistance to muscles and joints.
In some rehabilitation facilities and laboratories, lower-body exoskeletons and exosuits already are being used to improve walking ability in stroke patients, the elderly and young people with cerebral palsy or other disabilities. But perhaps the most tantalizing and vexing current science involves exoskeletons for the rest of us, including people who are young and healthy. In this area of research, scientists are developing exoskeletons to reduce the energy costs of running and walking, making those activities less fatiguing, more physiologically efficient and possibly more enjoyable.
So far, early results seem promising. In a series of studies conducted last year at Stanford University’s Biomechatronics Lab (and funded in part by Nike, Inc.), researchers found that college students could run about 15 percent more efficiently than normal on a treadmill when they wore a customizable, prototype version of a lower-leg exoskeleton. These exoskeletons feature a motor-powered lightweight frame strapped around the runners’ shins and ankles and a carbon-fiber bar inserted into the soles of their shoes. Together, these elements reduce the amount of force runners’ leg muscles need to produce to propel them forward. On real-world paths and trails, the devices might allow us to run at least 10 percent faster than on our own, the study’s authors estimate.
A slightly tweaked device likewise boosted the speed of young people while walking, according to a separate experiment from the Stanford lab, published in April. In that study, students walked about 40 percent faster, on average, when they wore a powered exoskeleton prototype, while incinerating about 2 percent less energy.
In essence, the exoskeleton technology could be considered “analogous to e-bikes,” but for striding, not pedaling, said Steven Collins, a professor of mechanical engineering at Stanford and senior author of the new studies. By reducing the effort needed to move, the powered machines theoretically could encourage us to move more, perhaps commute by foot, hang with or pass naturally speedier spouses or friends, and reach locales that might otherwise seem dauntingly hilly or far away.
They might even permit our muscles to power our cellphones, according to one of the more surprising of the new exoskeleton studies. In that experiment, published in May in Science, healthy, young volunteers at Queen’s University in Kingston, Ontario, wore an exoskeleton that included a backpack containing a small generator, which was attached to cables running down to their ankles.
While the volunteers walked for 10 minutes, the device collected some of the mechanical energy created by their leg muscles and transmitted it to the generator, which transformed it into a quarter of a watt of energy. (Most cellphones require several watts of energy to charge their battery.) At the same time, the exoskeleton reduced the physical effort involved in taking each step by about 2.5 percent.
“We foresee our device serving as a meaningful source of energy to power small electronic devices,” said Michael Shepertycky, a recent Ph.D. graduate at Queen’s University, who led the new study, making them handy during off-grid hikes, wildland firefighting or while ambling to the office.
None of the exoskeletons that are designed to better jogging or strolling are available outside of labs yet, although researchers expect that to change. “There is no doubt in my mind that within 10 years, exoskeletons and soft, wearable exosuits to improve mobility will be commercially available,” said Gregory Sawicki, a professor who directs the Human Physiology of Wearable Robotics lab at Georgia Tech University in Atlanta and wrote a commentary accompanying the study of electricity-generating exoskeletons.
It is still uncertain, though, whether off-the-shelf exoskeletons can be made affordable, comfortable or modish enough for most of us to wish to wear one. Even more fundamentally, we do not know if the devices, by lessening the effort involved in being active, might also diminish some of the usual health benefits of exercise.
“That is a concern,” Dr. Collins said. “But we hope people might run or walk more” while wearing the devices than without them, leading, over time, to greater cumulative amounts of activity. “The primary goal” of his and many other researchers’ exoskeleton research, he concluded, “is to try to make sure that if people want to be up and moving, they can be.”
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