Effect of burst-mode transcutaneous electrical nerve stimulation on peripheral vascular resistance.
OBJECTIVE
Based on changes in skin temperature alone, some authors have proposed that postganglionic sympathetic vasoconstrictor fibers can be stimulated transcutaneously. Our goal was to determine the effects of low-frequency (2 bursts per second), burst-mode transcutaneous electrical nerve stimulation (TENS) on calf vascular resistance, a more direct marker of sympathetic vasoconstrictor outflow than skin temperature, in subjects with no known pathology.


METHODS
Fourteen women and 6 men (mean age=31 years, SD=13, range=18-58) participated in this study.


METHODS
Calf blood flow, arterial pressure, and skin temperature were measured while TENS was applied over the common peroneal and tibial nerves.


RESULTS
Blood flow immediately following stimulation was not affected by TENS applied just under or just above the threshold for muscle contraction. Transcutaneous electrical nerve stimulation applied at 25% above the motor threshold caused a transient increase in calf blood flow. Regardless of stimulation intensity, TENS had no effect on arterial pressure; therefore, calf vascular resistance decreased only during the trial that was 25% above the motor threshold. Regardless of stimulation intensity, TENS failed to alter dorsal or plantar skin temperature.


CONCLUSIONS
These results demonstrate that the effects of TENS on circulation depend on stimulation intensity. When the intensity was sufficient to cause a moderate muscle contraction, a transient, local increase in blood flow occurred. Cooling of the dorsal and plantar skin occurred in both the stimulated and control legs, most likely because skin temperature acclimatized to ambient room temperature, rather than because of any effect of TENS on circulation. The data, therefore, call into question the idea that postganglionic sympathetic efferent fibers are stimulated when TENS is applied at clinically relevant intensities to people without symptoms of cardiovascular or neuromuscular pathology.
Sherry
J E
JE
4176 Medical Sciences Center, 1300 University Ave, Madison, WI 53706-1532, USA. sherry@surgery.wisc.edu
Oehrlein
K M
KM
Hegge
K S
KS
Morgan
B J
BJ
D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D010543:Peroneal Nerve / Q000502:physiology; D026741:Physical Therapy Modalities / Q000379:methods*; D012016:Reference Values; D012039:Regional Blood Flow; D012680:Sensitivity and Specificity; D013979:Tibial Nerve / Q000502:physiology; D004561:Transcutaneous Electric Nerve Stimulation / Q000379:methods*; D014655:Vascular Resistance / Q000502:physiology*