Duration of Electro-Dry Needling Does Not Change the Pain Response After Repeated Nociceptive Thermal Stimuli in Asymptomatic Individuals: A Randomized Intervention Study

OBJECTIVE: To assess the effects of 5 different durations of electro-dry needling (EDN) on asymptomatic individuals’ pain response after repeated noxious thermal stimuli. DESIGN: Randomized, non-controlled intervention trial. SETTING: University laboratory. PARTICIPANTS: Asymptomatic participants (N=50) were recruited for the study and randomized into 5 groups. There were 33 women with an average age of 26.8 (±4.8) years. To participate in the study, individuals had to be between the ages of 18 and 40, free of any musculoskeletal injury which prevented participation of daily activities, and not pregnant or trying to become pregnant. INTERVENTIONS: Participants were randomly assigned to receive 5 different durations of EDN: 10, 15, 20, 25, and 30 minutes. To perform the EDN, 2 monofilament needles were inserted lateral to the lumbar spinous processes of L3 and L5 on the right. Needles were left in situ with electrical stimulation at a frequency of 2 Hz and an amplitude which resulted in a 3 to 6 out of 10 intensity pain rating by the participant. MAIN OUTCOME MEASURES: The change in the magnitude of pain in response to repetitive heat-pulses before and after the EDN procedure. RESULTS: There was a significant reduction in the magnitude of pain in response across the groups after EDN (F((1,42))=94.12, P<.001, ƞ(p)(2)=.691). However, the interaction between time and group was not significant (F((4,42))=1.019, P=.409, ƞ(p)(2)=.088), indicating that no duration of EDN was superior to another in reducing temporal summation. CONCLUSIONS: This study suggests that in asymptomatic individuals, performing EDN beyond 10 minutes does not provide any additional benefits in the reduction of the magnitude of pain in response to thermal nociceptive stimuli. Additional study in symptomatic populations is required for generalizability in clinical settings.