Comparisons between surface electrodes and intramuscular wire electrodes in isometric and dynamic conditions

Area of Science:

• Biomechanics
• Neurophysiology
• Occupational Health

Background:

• Electromyography (EMG) is crucial for assessing muscle activity in occupational settings.
• Choosing between surface electrodes (SE) and intramuscular wire electrodes (IWE) impacts EMG signal reliability.
• Understanding electrode reliability is vital for accurate analysis of muscle function during working tasks.

Purpose of the Study:

• To compare the reliability of surface electrodes (SE) and intramuscular wire electrodes (IWE).
• To evaluate electrode performance during isometric and dynamic contractions in an occupational cervico-brachial working task (OCWT).
• To assess the day-to-day and within-day reliability of both electrode types.

Main Methods:

• Six adult males performed an occupational cervico-brachial working task under isometric and dynamic contraction conditions.
• Raw EMG signals from deltoid and trapezius muscles were recorded simultaneously using SE and IWE.
• Processed EMG data (full wave rectified, low-pass filtered, integrated EMG) were statistically analyzed using a repeated measures factorial model.

Main Results:

• Both SE and IWE demonstrated reliable EMG signal recordings between trials on the same day.
• Surface electrodes (SE) exhibited higher day-to-day reliability compared to intramuscular wire electrodes (IWE).
• Despite statistical similarity, a high coefficient of variability was observed between SE and IWE signals (48% isometric, 84% dynamic).

Conclusions:

• EMG recordings using both SE and IWE are reliable for within-day assessments of the OCWT.
• SE are recommended over IWE for more reliable day-to-day EMG investigations in this context.
• The significant variability between electrode types warrants careful consideration in EMG study design and interpretation.