Effect of Electrical Stimulation with Trigger Point Dry Needling on Pain and H-Reflex Muscle Activity

Background: The aims of this study were to determine the effects that trigger point dry needling (TpDN) with and without electrical stimulation (ES) has on pain threshold and to assess the effect the TpDN has on muscle activity (MA) in people with identified painful trigger points (Tp) within thesoleus and gastrocnemius muscles complex. Methods: This study was a randomized controlled trial. Forty volunteers, aged 18-55 were recruited, signed an informed consent and randomly placed in four equal groups: TpDN with simultaneous ES, DN only, ES only, and a Sham treatment (Tx). The parameters for ES were set to a frequency of 30 Hz, a pulse width of 0.6ms at an intensity causing a slight muscle contraction. Pain was assessed before and at 10 and 30 mins post Tx. MA was assessed using the H-reflex technique before, during and at 10 and 30 mins post-Tx. Data were analyzed using two 2-way repeated-measures ANOVA (pain and H-reflex). Post-hoc analysis followed when alpha <0.05. Cohen’s Ds was also calculated. Results: No significant change among the groups were found in the pain or H-reflex data (p > 0.5). However, the H-reflex showed significant changes within all groups over time, with DNES and ES showing the largest amplitude increase (DNES, Cohen’s D = 1.1; ES, Cohen’ D = 0.5). The other two groups showed smaller changes. Conclusions: TpDN Tx facilitated the H-reflex in all groups, with DNES showing the largest change. Thus, clinicians need to be cognizant of the facilitatory effect on MA when performing DNES. In addition, TpDN coupled with ES appears to have a synergistic effect on MA. As for pain thresholds, TpDN appears not to have an effect after one Tx. More may be necessary. Further research is needed to validate TpDN effect on pain. Trial Registration : This study was designed and conducted prospectively with IRB approval obtained in 2022 (Approval No. IRB 2122-042). Following the regulatory update in 2025, the study was retrospectively registered and assigned an NCT number (NCT07384247)to ensure compliance with current requirements.