Electromyography recordings of the tensor fascia latae muscle during dynamic tasks: A comparison of surface and fine-wire electrodes

      Introduction: The tensor fascia latae (TFL) is a small fusiform muscle that is active during flexion, abduction, and internal rotation of the hip. Surface electrodes are commonly used to record electromyography (EMG) from the TFL. Surface electrodes are susceptible to crosstalk from surrounding muscles. This study aimed to compare the patterns of TFL EMG recorded using surface and fine-wire methods during dynamic tasks.
      Methods: Eight healthy and physically active volunteers (5 females, 3 males; mean ± SD age 28 ± 6 years; height 1.70 ± 0.07 m; body mass 65.6 ± 10.3 kg; BMI 22.8 ± 3.4 kg/m2) participated in this study. TFL EMG was concurrently recorded with surface and fine-wire electrodes. Participants performed five trials of a step-up and a step-down task wearing their preferred footwear. EMG signals for all trials were visually inspected for artefacts. EMG data were amplitude-normalised to the maximum voluntary isometric contractions (MVIC, expressed as %). Statistical parametric mapping (SPM) was used to statistically compare the patterns of activation between electrode types.
      Results: Fine-wire recordings were technically more problematic than surface recordings (e.g., more frequent contamination by movement artefact), but acceptable for most participants. The difference between the pattern of TFL EMG from surface and fine-wire recordings varied between participants in both tasks. Some participants showed an additional major peak with surface recordings that was not apparent in the fine-wire recordings, and others showed the opposite. SPM revealed one supra-threshold cluster (between 10-15%) that exceeded the critical threshold (t*=3.516, p=0.013) during the step-up task. The MVIC normalised amplitude of surface recordings was significantly greater than fine-wire recordings during this period.
      Discussion: Although the pattern of TFL activity was variable between participants for both electrode types, surface recordings revealed activity that was absent in the fine-wire recordings, which strongly suggests contamination of surface recordings by activity from adjacent muscles (crosstalk). However, some participants showed opposite results (higher activity with fine-wire recordings than surface). For studies that aim to specifically understand the activation of TFL, fine-wire recordings are recommended considering the limitations of this technique.
      Conflict of interest statement: The authors have no conflict of interest of relevance to the submission of this abstract.