Blood flow variation in human muscle during electrically stimulated exercise bouts.
OBJECTIVE
To evaluate, with a high spatial resolution, the blood flow variations in human skeletal muscle during neuromuscular electric stimulation (NMES) and hence to gain better understanding of the mechanisms of muscle spatial recruitment during NMES.


METHODS
One thigh was submitted to 3 stimulation bouts of different durations (S1=4min, S2=8min, S3=12min) with a workload corresponding to 10% of quadriceps maximal isometric voluntary torque.


METHODS
A cyclotron research center at a Belgian university.


METHODS
Ten healthy male volunteers.


METHODS
Not applicable.


METHODS
Participants were studied with positron emission tomography and H(2)(15)O. Tissue blood flow was evaluated during the last 4 minutes of each stimulation bout in multiple regions of interest (ROIs) selected in the transverse section of the stimulated thigh.


RESULTS
Mean tissue blood flow was significantly lower during S1 (5.9+/-1.3mL. min(-1). 100g(-1)) than during S2 (10.6+/-3.4mL. min(-1). 100g(-1)) and S3 (11.6+/-3.7mL. min(-1). 100g(-1)) (P<.05). For each ROI, an arbitrary tissue blood flow activation level of 5mLmin(-1)100g(-1) was fixed. The mean percentage of activated ROIs reached 42.4%, 62.7%, and 63.6% during S1, S2, and S3, respectively. Between S1 and S3, the newly recruited ROIs were preferentially located far from the electrode.


CONCLUSIONS
During NMES, new muscular regions situated far from the stimulation site are recruited. These recruitment mechanisms are particular and contrast with the recruitment of motor units seen during voluntary contraction.
Vanderthommen
Marc
M
Department of Physical Medicine, University of Liège, Belgium. mvanderthommen@ulg.ac.be
Depresseux
Jean-Claude
JC
Dauchat
Luc
L
Degueldre
Christian
C
Croisier
Jean-Louis
JL
Crielaard
Jean-Michel
JM
D000328:Adult; D000704:Analysis of Variance; D001783:Blood Flow Velocity / Q000502:physiology; D004558:Electric Stimulation; D005080:Exercise Test; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012016:Reference Values; D012039:Regional Blood Flow / Q000502:physiology*; D013848:Thigh / Q000000981:diagnostic imaging / Q000502:physiology; D014055:Tomography, Emission-Computed