One of Associate Head Coach Burton Burns’ favorite drills for his Alabama running backs has them hopping over pads with both feet, teaching his players balance and more importantly how to recover from a stumble. One of his many star students was Trent Richardson, who liked the drill. “Even my freshman year when we were against North Texas and I had a long run and I could feel it near the end, someone just hit my feet,” Richardson told AL.com. “We get our feet up, it’s better for us to keep our balance.”
As you watch the video of the drill below, notice the stumbles after the second or third hurdle. Their brain engages in some fast calculations to sense the pending fall and sends signals out to the limbs to adjust for the unexpected body position. How exactly our brain senses a balance problem and how quickly we can adjust are the questions of two new research studies at McGill University and the University of Michigan.
“We’ve known for some time that the cerebellum is the part of the brain that takes in sensory information and then causes us to move or react in appropriate ways,” said Kathleen Cullen Ph.D. professor of psychiatry at McGill.
Through many trial and error episodes of moving around in a physical world, the brain learns the expected outcome of actions. When we don’t see the ice on the sidewalk or the cornerback diving at our feet from behind, we experience a “sensory conflict”. However, no one was able to isolate exactly where that happens in the brain.
Cullen’s research team, working with monkeys, was able to confirm the sensory conflict theory by isolating a group of neurons in the cerebellum that help decide which sensory information to pay attention to when the expected outcome doesn’t occur.
“What’s really exciting is that for the first time we show very clearly how the cerebellum selectively encodes unexpected motion, to then send our body messages that help us maintain our balance,” said Cullen. “That it is such a very exact neural calculation is exciting and unexpected.”
While this set of decision neurons instructs how to catch yourself, there are several parts of the brain that are activated at the start of the fall. Daniel Ferris, a professor of movement science at the University of Michigan invented a very unique treadmill modification to observe the brains of human walkers. By connecting a 4” wide beam to the middle of a treadmill belt, they asked volunteers to walk on a moving “tightrope” (see video below).
Next, a skull cap with electroencephalogram (EEG) electrodes was worn by each person and their brain activity was recorded while they walked and, eventually, stumbled off of the beam. They didn’t completely fall as they just stepped onto the rest of the treadmill belt.
“We’re using an EEG in a way others don’t, to look at what’s going on inside the brain,” said Ferris. “We were able to determine what parts of the brain first identify when you are losing your balance during walking.”
They were surprised by how many different areas of the brain were activated at the precise moment that a loss of balance occurred, and that the brain sensed a problem (measured by a change in activity) well before the muscles responded to the stumble.
By understanding how humans react to obstacles and falls, researchers can develop exercises that train the brain to maintain their balance. Coach Burns will certainly be the first in line to try them out. Watching Maryland’s Stefon Diggs earlier this season, he may already have some ideas.