Functional electrical stimulation effect on skeletal muscle blood flow measured with H2(15)O positron emission tomography.
OBJECTIVE
To test the hypothesis that the limitation in muscle power development with functional electrical stimulation (FES) results from an insufficient increase in muscle blood flow (MBF) in response to activity.


METHODS
Five subjects with neurologically complete spinal cord injury (SCI) were tested to measure the MBF response to FES-induced knee extension. The MBF response to voluntary knee extension was measured in five age-matched, able-bodied controls. MBF was measured with positron emission tomography (PET) using H2(15)O as a tracer. Three scans were performed with muscle at rest (baseline), immediately after 16min of FES-induced or voluntary knee extension (activity), and 20min after the second scan (recovery).


RESULTS
In SCI subjects, mean +/-SE MBF (mL/100g/min) values were: baseline = 1.85 +/- .48; post-FES = 31.9 +/- 5.65 (p = .0058 vs baseline); recovery = 6.06 +/- 1.52 (p = .0027 vs baseline). In able-bodied controls, mean +/-SE MBF values were: baseline = 8.52 +/- 3.24, post-voluntary exercise = 12.62 +/- 3.03 (p = .023 vs post-FES in SCI subjects); recovery = 10.7 +/- 6.01.


CONCLUSIONS
MBF does not appear to be the limiting factor in muscle power generation with FES. The greater increase in MBF observed with FES in SCI subjects when compared with able-bodied subjects performing a similar task (unloaded knee extension against gravity) may relate to abnormal metabolism in FES-stimulated muscle.
Scremin
O U
OU
Department of Research, West Los Angeles VA Medical Center, UCLA School of Medicine, CA 90073, USA.
Cuevas-Trisan
R L
RL
Scremin
A M
AM
Brown
C V
CV
Mandelkern
M A
MA
D000328:Adult; D001783:Blood Flow Velocity; D016022:Case-Control Studies; D004599:Electric Stimulation Therapy; D006801:Humans; D007866:Leg / Q000098:blood supply; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000000981:diagnostic imaging*; D011849:Radioactive Tracers; D013119:Spinal Cord Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy; D014055:Tomography, Emission-Computed; D014867:Water
D011849:Radioactive Tracers; D014867:Water