Learning to walk on err

Calculated missteps open gait to flexible adjustments

Stroke survivors and other patients trying to relearn how to walk due to weakness on one side of the body may reap benefits from being forced to stumble and stagger.

Healthy adults made to switch between a regular and an unusual walking pattern on a special treadmill relearned the strange stride much faster the next day than volunteers who had practiced only the unusual gait, neuroscientist Amy Bastian of the Kennedy Krieger Institute in Baltimore and her colleagues report in a study in the Oct. 19 Journal of Neuroscience.

Not surprisingly, participants who learned and then unlearned an unusual walking pattern while adjusting to a new walking style took lots of clumsy steps when trying to relearn the original pattern, some reminiscent of Monty Python’s old skit about the Ministry of Silly Walks. Yet these individuals had the last laugh, because they learned how to correct awkward leg limps and body lurches that occur in the early stages of adapting to a new gait, the researchers propose.

Practice at switching gaits helps people learn how to adjust for initial missteps when attempting an alternative walking style, Bastian says. She calls this process “learning to learn” from one’s mistakes, so that movements can be realigned quickly as needed.

Gait-switching volunteers weren’t aware that they learned anything, but the next day they realized that it was easier to adopt the odd walking style.

Standard therapy for stroke patients trying to relearn walking and other motor skills consists of practicing desired movements over and over. Bastian’s team plans to test whether training these patients instead to alternate between different treadmill strides improves their walking ability.

“The learning-to-learn effect has exciting potential for rehabilitation training,” remarks neuroscientist Rachael Seidler of the University of Michigan in Ann Arbor. Practice at learning and unlearning different gaits may also benefit astronauts and others whose jobs require moving in and out of novel environments, says Seidler, who studies how people acquire motor skills.

In the new study, Bastian and her colleagues trained 52 adults to walk on a split-belt treadmill. This contraption consists of separate belts that can be driven at the same speed for both legs or at different speeds, so that one leg has to move faster than the other to maintain balance.

One group was assigned to spend 15 minutes on belts moving at different speeds. A second group walked on belts that alternated between different speeds and identical speeds over 25 minutes. A third group negotiated belts moving at different speeds for 15 minutes, with two five-minute breaks.

The next day, participants who had practiced switching between normal and lopsided gaits needed substantially fewer steps than the others to relearn the unusual walking pattern.

A second treadmill experiment found that volunteers relearned a speeded-up right leg stride faster if they had practiced switching between that gait and a speeded-up left leg pattern the day before, versus practicing only the rapid right-leg walk.

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.

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