The effect of inter-electrode distance on radial muscle displacement and contraction time of the biceps femoris, gastrocnemius medialis and biceps brachii, using Tensiomyography in healthy participants.

Context: The systematic effect of inter-electrode distance on electrically elicited radial muscle displacement (Dm) and contraction time (Tc) of the biceps femoris, gastrocnemius medialis and biceps brachii using Tensiomyography (TMG) is currently unavailable. Aim: To investigate the effects of inter-electrode distance (4cm, 5cm, 6cm and 7cm) on Dm and Tc of the biceps femoris, gastrocnemius medialis and biceps brachii, when the current amplitude is standardised. Design: A within subject, repeated measures cross-over study. Participants: 24 participants. Results: Biceps femoris and gastrocnemius medialis Dm increased with increased inter-electrode distance (biceps femoris: p=0.015; gastrocnemius medialis: p=0.000), yet Tc were not affected (pagt;0.05). Biceps brachii Dm was not affected by inter-electrode distance (pagt;0.05), yet Tc became shorter with increased inter-electrode distance (p=0.032). Conclusion: Inter-electrode distance effects Dm but not Tc in two pennate muscles (biceps femoris and gastrocnemius medialis), and Tc but not Dm in one parallel muscle (biceps brachii). Optimal muscle specific inter-electrode distances were judged based on Dm measurements within the limits of this study. The following optimal inter-electrode distances are suggested; biceps femoris=6cm, gastrocnemius medialis=7cm and biceps brachii=4cm. Our findings emphasise the importance of accurate implementation and reporting of inter-electrode distance, for the reproducibility and comparability of studies using TMG.