title: Re-evaluation of EMG-torque relation in chronic stroke using linear electrode array EMG recordings.
abstract: The objective was to re-evaluate the controversial reports of EMG-torque relation between impaired and non-impaired sides using linear electrode array EMG recordings. Ten subjects with chronic stroke performed a series of submaximal isometric elbow flexion tasks. A 20-channel linear array was used to record surface EMG of the biceps brachii muscles from both impaired and non-impaired sides. M-wave recordings for bilateral biceps brachii muscles were also made. Distribution of the slope of the EMG-torque relations for the individual channels showed a quasi-symmetrical "M" shaped pattern. The lowest value corresponded to the innervation zone (IZ) location. The highest value from the slope curve for each side was selected for comparison to minimize the effect of electrode placement and IZ asymmetry. The slope was greater on the impaired side in 4 of 10 subjects. There were a weak correlation between slope ratio and strength ratio and a moderate to high correlation between slope ratio and M-wave ratio between two sides. These findings suggest that the EMG-torque relations are likely mediated and influenced by multiple factors. Our findings emphasize the importance of electrode placement and suggest the primary role of peripheral adaptive changes in the EMG-torque relations in chronic stroke.
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center - Houston, Houston, TX, USA.|TIRR Memorial Hermann Research Center, Houston, TX, USA.
authors.forename: Minal
authors.initials: M
authors.lastname: Bhadane
authors.affiliation: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.affiliation: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Chicago, IL, USA.
authors.forename: W Zev
authors.initials: WZ
authors.lastname: Rymer
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center - Houston, Houston, TX, USA.|TIRR Memorial Hermann Research Center, Houston, TX, USA.|Guangdong Work Injury Rehabilitation Center, Guangzhou, Guangdong Province, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhou
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center - Houston, Houston, TX, USA.|TIRR Memorial Hermann Research Center, Houston, TX, USA.
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D004551:Elbow Joint / Q000502:physiology*; D004576:Electromyography / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000502:physiology*; D020521:Stroke / Q000473:pathology*; D019415:Torque