Researchers at Johns Hopkins University say understanding how humans control the way they move their limbs in a repetitive way, such as in running, may aid in the treatment of people with neurological diseases and could lead to prosthetic limbs and robots that move more efficiently.
Jugglers, they said, rely on repeated rhythmic motions to keep multiple balls or other object aloft, and similar forms of rhythmic movement are also common in the animal world, where effective locomotion is equally important to a swift-moving gazelle and to the cheetah that's chasing it.
"It turns out that the art of juggling provides an interesting window into many of the same questions that you try to answer when you study forms of locomotion, such as walking or running," mechanical engineering Professor Noah Cowan said.
"In our study, we had participants stand still and use their hands in a rhythmic way," he said. "It's very much like watching them move their feet as they run. But we used juggling as a model for rhythmic motor coordination because it's a simpler system to study."
Vision is the main sense to control movements, the researchers found, but the sense of touch -- important to a juggler -- improves that control.
"The human nervous system gets feedback all of the time from our sense of vision," study lead author M. Mert Ankarali said. "But the important thing about the sense of touch while juggling is that we get a precise timing cue that complements the continuous visual feedback. This timing cue is very important for us to get the rhythm of the juggling task."
The brain's ability to instantly integrate information coming from both the eyes and the sense of touch is a critical part of successful running, juggling and other repetitive movements, the researchers said.