Surface electromyography of the foot: A protocol for sensor placement

Area of Science:

• Biomechanics
• Neuroscience
• Musculoskeletal research

Background:

• Surface electromyography (sEMG) is widely used for muscle activity recording.
• Previous studies on intrinsic foot muscles using sEMG were limited due to technological constraints, often requiring fine-wire electrodes.
• This study addresses the need for reliable sEMG protocols for intrinsic foot muscles.

Purpose of the Study:

• To evaluate the reliability of a surface EMG protocol for assessing intrinsic foot muscles.
• To establish a standardized sEMG protocol for intrinsic foot muscle analysis.
• To identify potential challenges and areas for improvement in sEMG application for foot muscles.

Main Methods:

• Six intrinsic foot muscles were identified using ultrasound and functional testing.
• A standardized sEMG sensor placement protocol was developed.
• Repeatability and reliability were assessed across multiple testers, subjects, and time sessions using Intraclass Correlation Coefficient (ICC) and percentage standard error of measurement.

Main Results:

• Good correlation was observed for Extensor Digitorum Brevis, Dorsal Interossei, Abductor Digiti Minimi, and Flexor Digitorum Brevis.
• Increased variability and poor correlation were found for Flexor Hallucis Brevis and Abductor Hallucis.
• Low precision of measurement was indicated by the percentage standard error of measurement, despite high ICC values.

Conclusions:

• Inconsistent reliability of sEMG for intrinsic foot muscles was demonstrated due to variability between testers and sessions.
• Further research and protocol refinement, potentially focusing on muscle grouping, are necessary to improve understanding and measurement accuracy.
• The findings highlight the need for optimized sEMG techniques for reliable intrinsic foot muscle assessment.