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Exp Brain Res. 2018 Jul;236(7):2009-2021. doi: 10.1007/s00221-018-5275-6. Epub 2018 May 5.

Unilateral wrist extension training after stroke improves strength and neural plasticity in both arms.

Sun Y1,2,3, Ledwell NMH4, Boyd LA4, Zehr EP5,6,7,8.

Author information

1
Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC, V8P5C2, Canada.
2
Human Discovery Science, International Collaboration on Repair Discovery (ICORD), Vancouver, BC, V5Z1M9, Canada.
3
Division of Medical Science, University of Victoria, Victoria, BC, V8P5C2, Canada.
4
Brain Behaviour Laboratory, University of British Columbia, Vancouver, BC, V6T1Z3, Canada.
5
Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC, V8P5C2, Canada. pzehr@uvic.ca.
6
Human Discovery Science, International Collaboration on Repair Discovery (ICORD), Vancouver, BC, V5Z1M9, Canada. pzehr@uvic.ca.
7
Division of Medical Science, University of Victoria, Victoria, BC, V8P5C2, Canada. pzehr@uvic.ca.
8
Rehabilitation Neuroscience Laboratory, University of Victoria, PO Box 3010 STN CSC, Victoria, BC, V8W 3P1, Canada. pzehr@uvic.ca.

Abstract

Stroke induces bilateral neurological impairment and muscle weakness yielding neurologically more (MA; paretic) and less affected (LA; non-paretic) sides. "Cross-education" refers to training one side of the body to increase strength in the same muscles on the untrained side. Past work showed dorsiflexion training of the LA side produced bilateral strength increases after stroke. The current study explored the presence and extent of cross-education after arm strength training in chronic stroke. Twenty-four chronic stroke participants completed 5 weeks of maximal wrist extension training using their LA arm. Maximal voluntary contraction force, arm motor impairment and functional performance were measured before and after training. Both spinal cord plasticity (nā€‰=ā€‰12: reciprocal inhibition and cutaneous reflexes, University of Victoria) and cortical plasticity (nā€‰=ā€‰12: cortical silent period, short-interval intracortical inhibition, intracortical facilitation and transcallosal inhibition, University of British Columbia) were assessed. Five weeks after training, 20 participants completed a follow-up maximal wrist extension retention test. LA wrist extension force increased 42% and MA by 35%. Strength gains were maintained in the follow-up test. Clinically meaningful increases in Fugl-Meyer scores were noted in four participants. Muscle activation was correlated with cutaneous reflex amplitudes after training in the MA arm. LA cortical silent period and transcallosal inhibition from both hemispheres significantly decreased after training. This study shows that high-intensity training with the neurologically less affected "non-paretic" arm can improve strength bilaterally and alter both spinal and cortical plasticity. The extent to which this plasticity can be enhanced or functionally exploited remains to be examined.

KEYWORDS:

Cross-education; Neuroplasticity; Rehabilitation; Strength training; Stroke

PMID:
29730752
DOI:
10.1007/s00221-018-5275-6
[Indexed for MEDLINE]

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