Movement speed may not affect motor-learning after stroke

By Rob Goodier

NEW YORK (Reuters Health) - Training at high speed or low speed may not make a difference to stroke victims learning to regain motor control, a new study suggests.

Stroke patients "improve accuracy of reaching after four days training whether they are trained to move fast or slow," said John Rothwell, a physiologist who studies motor control at the UCL Institute of Neurology in London.

But "the mechanism of the improvement appears to differ from that in healthy individuals," he said. Stroke patients "improve by reducing directional error, whereas healthy people improve by reducing distance errors."

Dr. Rothwell and his team presented their results November 9 at the annual meeting of the Society for Neuroscience in San Diego, California.

Stroke victims often train by making slow movements toward a goal and focus on their accuracy, not their speed. The researchers were interested in how the speed of motion might affect accuracy.

To investigate, they randomly assigned 24 stroke patients and 14 healthy controls to learn reaching movements in a robotic manipulandum at either fast or slow speeds. The outcomes were tied to two factors, the direction of the reach and the distance from the target - how much it was overshot or undershot.

In the slow-movement exercises the participants could take as long as they liked to try to reach for the target. In the fast exercises they had a time limit.

During six consecutive days of training, functional ability improved and spasticity in the biceps decreased significantly in all of the groups.

Overall, improvements in accuracy at one speed appear to have crossed over to improve the accuracy at the other speed, the study found.

That was one of the more surprising findings, according to Dr. Amy Bastian.

Dr. Bastian, a neuroscientist at The Johns Hopkins School of Medicine who was not involved in the research, told Reuters Health, "There is some work that suggests high speed walking training is beneficial for stroke survivors. However, the concept of training arm movements at high speeds is rather novel in the stroke literature. As such, this is an interesting and timely study."

Dr. Rothwell did not respond to requests for comment.

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