If you blow out your knee or have major joint surgery, your doctor will likely recommend or even require physical therapy. By doing repeated physical exercises, you relearn how to move that body part, which can certainly help you get back up to speed. However, a new study suggests PT skips a key component of recovery: retraining the brain.
Using MRI scans on patients recovering from ACL reconstructions, researchers at The Ohio State University Wexner Medical Center discovered that their brains processed information from their injured leg differently than from their healthy leg — and differently than how uninjured people process info. These guys relied much more heavily on visual cues when moving their reconstructed knee and didn’t move it as instinctively as they did their other knee.
“When we asked participants to move their leg in a simple bend, the MRIs showed they used a visual processing system, even though this was not a visual task,” says Jimmy Onate, lead researcher and director of Health and Rehabilitation Sciences at OSU. “There was no reason to use their vision — they were not asked to avoid obstacles or use their eyesight in any way. But because nerve endings get damaged with musculoskeletal injuries, we think people begin relying on vision more to use, control, and monitor their movements.”
The problem with becoming overly dependent on your eyes is that you end up not retraining the joint to move naturally. Furthermore, you’re kidnapping your vision and devoting it to otherwise simple movements, when it would be better served watching out for fallen branches on your running trail or anticipating the next pass on the basketball court.
“Think about vision from a cost-of-resources standpoint,” Onate says. “We only have a certain amount of it. If you’re walking down a wide, brightly lit hallway and don’t need to judge whether to go faster or slower or move right or left, then you can afford to use some of your vision for movement. But if you need to react to anything — say, you’re crossing a busy road or you’re on the court and need to know where the ball is and where your teammates are — then you don’t want to use up your vision on moving your knee.”
Now that the researchers have discovered this disparity in information processing, they’ve begun testing out a method to fix it. In hopes of training patients to not depend on vision after ACL reconstruction, they’re having them wear stroboscopic eyewear during some physical therapy sessions. Also dubbed “strobe glasses,” these dark-hued specs are similar to sunglasses, making it much tougher to see in a bright therapy setting. But they also have shutters that open and close rapidly, creating a strobe light–like effect that interferes, distorts, and forces the body to move instinctively rather than by sight.
“We’re taking away some of their vision but not blinding them completely and then also adding the visual-disturbance element,” Onate says. “You can’t just rehab someone on a soccer field because their leg is not ready.” But by re-teaching movements in a safe environment with impaired vision, Onate feels they can better prepare patients for resuming real life and real activities.
Stroboscopic eyewear isn’t entirely new in the world of sports. Since these glasses came onto the scene a few years back, pro athletes have used them to help hone their skills and quicken their reaction times. In 2013, Duke University researchers even tested them out on members of the NHL’s Carolina Hurricanes. After wearing the glasses during their 16-day preseason training camp, players performed 18 percent better on shooting and passing tests than their teammates who didn’t sport the specs.
But bringing stroboscopic eyewear into the therapy setting is an entirely new concept, one that Onate thinks may have real merit. “Using these glasses in physical therapy is not mainstream by any means, and we’re still looking at the pros and cons and for how long and when they should be used,” he says. But if Onate’s next round of experiments proves successful, strobe glasses could soon become an ingrained part of PT.
Onate warns that people with seizures, migraines, or past concussions steer clear of strobe glasses because they may exacerbate symptoms. But for everyone else recovering from injury, he advocates trying them at home — that is, if you want to spring the $400 for the glasses online. Just don’t use them right out of the gate. “We do almost all activities with eyes open at first,” he adds. “Next you can move onto eyes closed. Then later, when you’re working on single-leg movements and other exercises, you can try the glasses.”