Effectiveness of Transcutaneous Neuromodulation on Abductor Muscles Electrical Activity in Subjects with Chronic Low Back Pain: A Randomized, Controlled, Crossover Clinical Trial

Introduction: Non-specific chronic low back pain (NSCLBP) is a major cause of functional impairment, resulting in consequences like job absenteeism and reduced quality of life. Risk factors such as muscle weakness and tightness have been implicated. Electromagnetic fields have therapeutic effects on human tissue, including pain relief and muscle relaxation. This study aimed to examine the impact of a tape with magnetic particles (MPT) applied to the lumbar area on abductor muscle strength and surface electromyography (sEMG) of the Gluteus Medius and Tensor of the Fascia Lata muscles in individuals with NSCLBP. Methods: It was carried out a double-blind, randomized, controlled, crossover trial and with test retest, with 41 consecutive patients younger than 65 years who previously diagnosed with NSCLBP to assess the effect of a MPT over hip abductor muscle strength and activity. sEMG and force data were obtained during the Hip Stability Isometric Test (HipSIT). The HipSIT was used to assess the abduction strength using a hand-held dynamometer and sEMG. The HipSIT uses the maximum voluntary isometric contraction (MVIC). Four trials were recorded and the mean extracted for analysis. The tape was applied with either a MPT or a sham magnetic particle tape (SMPT) bilaterally without tension on from L1 to L5 paravertebral muscles. Results: The significant increase in the recruitment of fibers and the significant increase in the maximum voluntary contraction by applying MPT with respect to the SMPT, correspond to the increases in the Peak Force and the decrease in the time to reach the maximum force (peak time) of both muscles. Conclusion: Application of a MPT in patients with NSCLBP suggests an increase in muscle strength of the Gluteus Medius and the hip musculature.