Stroke victims recover use of weakened limbs by exercising unaffected limbs, research finds
Date Posted: 21.12.2012
Stroke victims can make astonishing gains in strength in weakened limbs by training the unaffected limbs on the other side of their body, according to new research by the University of Victoria.
Neuroscientist Paul Zehr and PhD candidate Katie Dragert designed “ridiculously simple” devices made of wooden boards and cloth straps that stroke victims used to strengthen the muscles in their legs and ankles. Patients completed a six-week high-intensity training regime — not with the limbs weakened by the stroke, but with the limbs that were less affected or unaffected.
What happened surprised even the researchers.
Patients gained as much strength in the weakened leg as they did in the leg that did the exercises. Patients achieved strength gains of about 30 per cent in both the trained and untrained legs, a far more dramatic effect than previous research on healthy people had achieved.
The finding promises to be a boon to patients whose limb strength is so impaired by stroke that they can’t lift or train the affected parts at all.
“Weakness is a big part of what happens after a stroke and if you can do something to increase people’s strength, you can help them get walking and all kinds of stuff,” said Zehr.
Patients in the study suffered their stroke on average about 80 months before training. That suggests patients can benefit from the program years after a debilitating event.
Study participant Barb Oliver suffered from weakness in her left leg after a stroke 10 years ago, but continues to make gains through UVic’s experimental programs.
“I couldn’t walk at all and they didn’t think I would ever walk again,” said Oliver. “Now, I get around with a cane.”
Zehr and Dragert employed a mostly forgotten 1894 discovery by Yale University researchers who found that when people train one arm, the other arm also gained strength.
“The arm that they trained got stronger, but the other arm got stronger, too, even though it wasn’t trained,” Zehr explained. “Over the years people have looked at cross-education of strength on different parts of the body, upper and lower limbs, and it pretty much shows up everywhere to a greater or lesser degree.”
Most of the research found that the untrained limb gains about half as much strength as the trained limb.
“A 30-per-cent gain on the trained side usually results in a 15-per-cent gain on the untrained side,” he said. “We thought that with all the damage caused by the stroke that we might see a five- or 10-per-cent gain in our patients’ untrained limbs.”
But the strength gains recorded in the UVic study of stroke victims were twice as high as the gains achieved by healthy people in past studies.
Much of the training gain in strength and skill that people achieve through exercise takes place in the brain and the nervous system rather than the muscles themselves, Zehr said.
The surprising strength of the cross-education effect suggest the training program may be tapping into communication pathways between the left and right sides of the brain and activating built-in — but little used — duplications in the neural wiring that controls movement, he said.
The study will be published in the journal Experimental Brain Research and has been published by that journal online.
Source : http://blogs.vancouversun.com/2012/12/10/stroke-victims-recover-use-of-weakened-limbs-by-exercising-unaffected-limbs-research-finds/