Effects of High-Frequency Electrical Stimulation on the Autonomic Nervous System in Low Back Pain: A Randomized Crossover Trial

Effects of capacitive resistive monopolar radiofrequency (CRMRF) on the thoracic spine, where the sympathetic ganglia are located, remain unclear. This study aimed to investigate the effects of CRMRF applied to the thoracic spine on autonomic nervous system activity and pain-related psychological responses in individuals with non-specific low back pain (LBP). This randomized crossover trial included 10 participants with non-specific LBP. Each participant received three interventions in separate sessions: CRMRF, hot pack, and sham (inactive CRMRF). Heart rate variability (HRV) was assessed from intervention initiation to 30 minutes post-intervention, while Pain Catastrophizing Scale (PCS) scores were assessed pre- and post-intervention. HRV analysis included high-frequency (HF) and low-frequency (LF)/HF components, indicating parasympathetic and sympathetic activity, respectively. CRMRF significantly altered HF activity, with an initial decrease during the intervention followed by a post-intervention increase. No significant changes were observed in the LF/HF ratios. PCS scores improved over time, but no significant differences were found between interventions.In conclusion, CRMRF applied to the thoracic spine modulates parasympathetic activity. CRMRF influences autonomic regulation and may contribute to pain relief. Additionally, targeting the thoracic spine may be a useful approach for LBP management by influencing both autonomic function and pain-related psychological responses. Trial registration: UMIN Clinical Registry UMIN000057614. 2025/04/15. Retrospectively registered.