Normalisation of gait EMGs: a re-examination

Area of Science:

• Biomechanics
• Neuroscience
• Kinesiology

Background:

• Electromyograms (EMGs) are crucial for analyzing muscle activity during gait.
• Accurate normalization of EMG data is essential for reliable interpretation of muscle activation patterns.
• Current normalization methods vary, necessitating a comparison of their effectiveness.

Purpose of the Study:

• To compare four different methods for normalizing electromyograms (EMGs) recorded during normal gait.
• To evaluate the impact of normalization methods on EMG amplitude, intra-individual variability, and inter-individual variability.
• To determine the most suitable normalization method for gait analysis.

Main Methods:

• Surface EMGs were recorded from lower limb muscles during treadmill walking.
• EMGs were also recorded during isometric and isokinetic maximal voluntary contractions (MVCs).
• Gait EMGs were normalized using mean dynamic, peak dynamic, isometric MVC, and isokinetic MVC methods.

Main Results:

• The isokinetic MVC method resulted in significantly greater intra-individual and inter-individual variability compared to other methods.
• EMG patterns and amplitudes normalized using isometric and isokinetic MVC methods were highly similar.
• The isokinetic MVC method did not offer advantages in reducing variability or representing muscle activation during gait.

Conclusions:

• The isokinetic MVC method is not recommended for gait researchers or clinicians.
• Existing normalization methods, such as the isometric MVC method, are more effective in reducing variability.
• The isometric MVC method provides a comparable and more reliable measure of muscle activation during gait analysis.