A new study from Simon Fraser University may revolutionize the way that humans are trained for sports or how we are rehabilitated after injuries. The researchers have uncovered new clues about how the nervous system learns the optimal ways to move the human body.
“How does our brain figure out how to best move our body? It turns out that this can be a challenging problem for the nervous system, considering we have hundreds of muscles that can be coordinated hundreds of times per second – with more possible coordination patterns to choose from than moves on a chessboard,” explained study senior author Professor Max Donelan.
“We often experience changes to our body and our environment. Perhaps you enjoy a long run on a Saturday morning – your muscles may fatigue as the length of the run increases. Perhaps you choose to run on the beach on vacation – the sand may be uneven and loose in comparison to the pavement on the sidewalk. While we might register that these changes have occurred, we might not appreciate how our body adapts to these changes.”
In collaboration with mechanical engineers at Stanford, Professor Donelan’s team of neuroscientists investigated the walking characteristics of study participants who were wearing exoskeletons.
The study revealed that, in order to learn a new movement coordination pattern, the nervous system adapts by evaluating many different options. This evaluation measures the variability across levels of movements in the joints and muscles.
Ultimately, the team found that the nervous system learns to adapt to specific aspects of movement and simultaneously decreases variability among these aspects. The study also showed that these adaptive changes can improve movement while reducing the energy cost of walking by about 25 percent.
“We created new contexts using exoskeletons that act to assist walking, and then studied how people explore new movements and learn more optimal ones,” said study lead author Sabrina Abram.
The experts report that the nervous system appears to benefit from first searching among many different coordination patterns, and also benefits from reducing this search space over time. “This is because continuing to search among coordination patterns that already reduce energy can in turn increase energy, as well as add to the already challenging problem of figuring out the best way to move,” said Abram.
“We would all like to move in the best way possible,” said Professor Donelan. “For healthy people, it seems that, with the right circumstances, the brain can take care of this. For those recovering from an injury, we might learn about how to best rehabilitate this injury from a better understanding of how the nervous system learns to adapt.”
The research is published in the journal Current Biology.