Carrying a heavy load changes the mechanics of how we walk and often leads to exhaustion and injuries, including back strain and knee pain. Routinely, though, first responders, laborers, soldiers, and even some athletes are required to bear hefty burdens while walking. Helping them to prevent any health issues from arising, a new Harvard study suggests a flexible exosuit might do just the trick.
A team of researchers, led by Professor Conor J. Walsh, say their newly designed exosuit reduces the amount of energy we use while walking by 7.3 percent on average. At the same time, their flexible suit significantly reduces the level of work the hips, knee, and ankle joints perform, without impacting step frequency or length.
Along with assisting load carriers, the team is exploring how their soft exosuit might be used to assist people with compromised abilities. “We hope it could also be useful for the elderly in the future,” Walsh told Medical Daily.
When thinking of an exoskeleton, it’s natural to think of something rigid, tough and, well, skeletal. For example, the lobster is a marine animal with a rigid exoskeleton, one that supports and protects the soft tissues and organs it encases. Quite possibly, the humble lobster inspired the idea to create a human exoskeleton, but no matter how the notion originated it has endured over time. In days long past, suits of armor protected the soft bodies of warriors, while more recently, comic book writers (and movie makers) endow futuristic heroes with supercharged exoskeletons that protect the body while also extending physical abilities. Notable examples include Iron Man and Batman.
Because the idea of a tough exosuit has been so lasting, it is surprising that Walsh and his colleagues dreamed up a soft suit.
“We wanted to deliver low to moderate assistance with a lightweight and non-restrictive platform,” Walsh said.
So, he and his team used textiles to build their suit, which they constructed into a waist belt, two thigh pieces, and two calf straps, all connected by cables to two motors mounted on a backpack. The energy from the motors travels via the cables to the suit. In turn, the suit transfers energy to the wearer when it detects a walking motion. Specifically, the exosuit assists the hip and ankle joints, which contribute about 80 percent of the power produced during ambulatory movement.
To see if the suit reduced the amount of energy needed while walking, the researchers tested it under three separate conditions with seven experienced and injury-free load carriers. Monitoring metabolism and kinetics (the forces that influence the movements of the body) in addition to breathing, gait, and muscle activity, the researchers found the sum of work done by the hip, knee, and ankle joints was significantly reduced. However, only small differences were measured in muscle activation.
Still, the movements of each walker seemed unhindered despite carrying a load equal to 30 percent of their body mass. “Based on the results of this study, we believe that there is potential for further enhancing the exosuit’s performance,” concluded Walsh and his colleagues who continue to research their design for a variety of different uses.
Source: Panizzolo FA, Galiana I, Asbeck AT, et al. A biologically-inspired multi-joint soft exosuit that can reduce the energy cost of loaded walking. Journal of NeuroEngineering and Rehabilitation. 2016.