Differences in current amplitude evoking leg extension in individuals with spinal cord injury.
OBJECTIVE
To investigate the effects of regional thigh composition that result in different responses to current amplitude among individuals with spinal cord injury (SCI) during applications of surface neuromuscular electrical stimulation (NMES) to evoke dynamic leg extension.


METHODS
Cross-sectional.


METHODS
Academic Settings.


METHODS
Five males with chronic motor complete SCI completed 3 visits of NMES to determine the current amplitude required to evoke full knee extension. The participants underwent magnetic resonance imaging of both thighs to measure skeletal muscle cross-sectional area (CSA), thigh subcutaneous adipose tissue (SAT) and intramuscular fat (IMF). Applicants were classified into high (n = 3) and low-responders (n = 2) based on the determined current amplitude.


RESULTS
The low-responders required 48-59% greater current amplitude to complete the same task as the high-responders. Low-responders had greater thigh SAT CSA (51-56%) than the high-responders with SCI. After adjusting to whole thigh CSA, IMF CSA was significantly greater in the low- responders; whereas skeletal muscle CSA was lower compared to the high-responders.


CONCLUSIONS
The findings suggest that thigh SAT and IMF act as insulation against propagation of current during surface NMES applications in individuals with SCI.
Spinal Cord Injury and Disorders Center, Hunter Holmes McGuire VAMC, Richmond, VA, USA.
Ashraf S
AS
Gorgey
Gilbert M
GM
Cho
David R
DR
Dolbow
David R
DR
Gater
D000273:Adipose Tissue; D050154:Adiposity; D000328:Adult; D003430:Cross-Sectional Studies; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor; D006801:Humans; D007866:Leg / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013848:Thigh / Q000473:pathology