EFFECT OF TRANSCUTANEOUS ELECTRICAL NERVE-STIMULATION ON THE PRESSOR-RESPONSE TO STATIC HANDGRIP EXERCISE

Background and Purpose. A proposed mechanism for the pain-relieving pr operties of transcutaneous electrical nerve stimulation (TENS) is gati ng of impulses carried by group III and IV afferent nerve fibers. The purpose of this study was to determine the effects of TENS on the pres ser response to static exercise, a response mediated by group III and IV muscle afferents. Subjects. Sixteen subjects (9 men, 7 women) with no known history of cardiovascular, neurologic, or musculoskeletal dis ease participated. Methods. Mie measured arterial pressure, heart rate , and sympathetic activity during sustained, 25% maximal handgrip exer cise. Each subject performed the handgrip exercise with and without co nventional TENS applied to the ipsilateral forearm and, in a separate trial, to the contralateral leg. Results. The sympathetically mediated presser response to handgrip exercise was blunted when TENS was appli ed to che ipsilateral forearm, but not when TENS was applied to the co ntralateral leg. Conclusion and Discussion. These data support the con cept that central transmission of neural impulses traveling in group I II and IV fibers can be modulated by other afferent inputs converging on the same spinal level.