title: Hypoalgesia in response to transcutaneous electrical nerve stimulation (TENS) depends on stimulation intensity.
abstract: Transcutaneous electrical nerve stimulation (TENS) is an electrophysical modality used for pain management. This study investigated the dose response of different TENS intensities on experimentally induced pressure pain. One hundred and thirty TENS naïve healthy individuals (18-64 years old; 65 males, 65 females) were randomly allocated to 5 groups (n = 26 per group): Strong Non Painful TENS; Sensory Threshold TENS; Below Sensory Threshold TENS; No Current Placebo TENS; and Transient Placebo TENS. Active TENS (80 Hz) was applied to the forearm for 30 minutes. Transient Placebo TENS was applied for 42 seconds after which the current amplitude automatically reset to 0 mA. Pressure pain thresholds (PPT) were recorded from 2 points on the hand and forearm before and after TENS to measure hypoalgesia. There were significant differences between groups at both the hand and forearm (ANOVA; P = .005 and .002). At 30 minutes, there was a significant hypoalgesic effect in the Strong Non Painful TENS group compared to: Below Sensory Threshold TENS, No Current Placebo TENS and Transient Placebo TENS groups (P < .0001) at the forearm; Transient Placebo TENS and No Current Placebo TENS groups at the hand (P = .001). There was no significant difference between Strong Non Painful TENS and Sensory Threshold TENS groups. The area under the curve for the changes in PPT significantly correlated with the current amplitude (r(2) = .33, P = .003). These data therefore show that there is a dose-response effect of TENS with the largest effect occurring with the highest current amplitudes.
  
  
  CONCLUSIONS
  This study shows a dose response for the intensity of TENS for pain relief with the strongest intensities showing the greatest effect; thus, we suggest that TENS intensity should be titrated to achieve the strongest possible intensity to achieve maximum pain relief.
authors.affiliation: Health and Rehabilitation Sciences Research Institute, University of Ulster, United Kingdom.
authors.forename: Fidelma
authors.initials: F
authors.lastname: Moran
authors.forename: Tracey
authors.initials: T
authors.lastname: Leonard
authors.forename: Stephanie
authors.initials: S
authors.lastname: Hawthorne
authors.forename: Ciara M
authors.initials: CM
authors.lastname: Hughes
authors.forename: Evie
authors.initials: E
authors.lastname: McCrum-Gardner
authors.forename: Mark I
authors.initials: MI
authors.lastname: Johnson
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Rakel
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Sluka
authors.forename: Deirdre M
authors.initials: DM
authors.lastname: Walsh
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D055592:Biophysical Phenomena / Q000502:physiology*; D001703:Biophysics; D004311:Double-Blind Method; D005260:Female; D006225:Hand / Q000294:innervation; D006801:Humans; D006930:Hyperalgesia / Q000503:physiopathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000523:psychology; D059408:Pain Management / Q000379:methods*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D004561:Transcutaneous Electric Nerve Stimulation / Q000379:methods*; D055815:Young Adult