What have your undies done for you today? They may blanket your behind, pad your periods, or even filter your flatulence. But if Karl Zelik has anything to do with it, underwear of the future may also help prevent back pain.
Zelik is a biomedical engineer at Vanderbilt University who researches lower limb biomechanics and prosthetics. Before his current research, he says, "I've never really thought about spine biomechanics or lower back pain in any depth."
But two years ago, his life changed; He became a father.
Since that eventful day, his son has grown increasingly heavy, and lifting him has taken a toll on Zelik's back. So he turned this pain into productivity, and began investigating pain prevention using a concealable wearable gadget. Now after several years of research and hundreds of iterations, his so-called "smart underwear"—which he and the team have filed to patent—is making its U.S. debut this week at the American Society of Biomechanics conference in Boulder, Colorado.
Every time you lift or lean, you have to contract your lower back muscles to "prevent you from falling on your face," Zelik explains. But people in jobs that require extensive lifting or leaning (or dads toting their children around) constantly use these small back muscles, which can eventually lead to pain from overuse or even injury.
According to the 2015 Global Burden of Disease analysis, neck and back pain have become the "leading global cause of disability" in most countries. Up to 80 percent of people experience back pain at some point during their lifetime. And as injury rates soar, so has the use of back belts, but there is insufficient evidence these actually help prevent back injury, according to the Centers for Disease Control website.
Enter Zelik. He hopes to tackle the problem of back pain with a wearable, assistive device that can help with lifting, but doesn't require a bulky Ironman-like exoskeleton. In brief, the smart underwear consists of a vest and a pair of bike-short-like bottoms, connected by a set of straps that criss-cross from shoulder to shorts along the back. Each of these straps has two sections: a stretchy upper elastic and a lower firm, rubber-like material.
The device contains a tiny motor, smaller than a tube of lip balm, housed in the front pocket of the vest. If you bend over while the device is in the "off" position, the stretchy elastic moves with your body. "It would just feel like normal clothing," says Zelik. When it's switched on, however, a pair of "clutches" prevents the elastic from stretching. When you bend over, the tough, rubber-like material attached to the thighs becomes taut, taking off some of the pressure that would otherwise be placed on your muscles.
"It's a bit like compression garments, but specially designed to transfer force to your legs in a way that won't slip or give you a wedgie," says Zelik.
The team is still working out the optimal way to signal to the device that you're dipping down, but currently it can be done by tapping the front of the vest, using a smartphone app, or gesturing while wearing a specially made armband.
The researchers tested their prototype on eight subjects who had to lift 25 and 55 pound weights as well as lean over at three different angles. To actually quantify the benefits of the underwear, they attached sensors to the wearer's body to measure the natural electrical potentials generated during muscle contraction. The tests suggest that the smart underwear can reduce the load on the back by 15 to 45 percent, depending on the task, says Zelik.
"I think it's a practical solution that is based on an elegant design," says Conor Walsh, a biomechanical engineer at Harvard University, who was not involved in the development of the new garment. Walsh's research focuses on the use of robotic technology to augment and restore human performance, including the development of soft exosuits to assist with trekking long distances.
"It's really exciting to see more people working in this area," he says. A lot of groups who work with similar assistive technologies have focused on the legs, Walsh explains, but this latest design "demonstrates that you can apply these kinds of tissue or muscle unloading techniques in different parts of the body."
Though the latest iteration isn't quite ready for market, Zelik’s team is inching closer. "There's still a lot of research to be done," he says. He plans to test how the device impacts fatigue with repetitive tasks or holding a leaning position for an extended period of time. He also hopes to study the long-term effects of wearing the smart underwear—with frequent washing, of course—to see if the moderate assistance can actually help reduce incidence of injury, or if it causes any unintended consequences.
"What's cool is it's a proof of concept that showed that [all of the device's parts] could fit into a very small form factor," says Zelik. "You don't need a big wearable robot to fit around you." One of his directives for the project was that every part of the prototype could be made out of smaller or thinner materials for a production model. He expects future versions to be more easily hidden under clothes.
To be clear, Zelik emphasizes, the device is intended to prevent back pain from starting in the first place, not treat it once it strikes. But the team’s tests suggest that this is a promising method to reduce loading on the back during strenuous lifting and other tasks.
When asked how long until wearables such as Zelik’s make it to market, Walsh doesn't hesitate to answer. "Definitely within five years," he says. "The reason that I'm convinced of that is a lot of these systems are really designed with simplicity and practicality in mind," he says. "They're not the Ironman suits that needs a nuclear reactor in the chest to power them."
But, as with getting most new-fangled tech products to market, that timeline is elastic.