Influence of electrode type on neuromuscular activation patterns during walking in healthy subjects.

The role of muscle activation in both pathological and spastic populations is of interest for understanding central nervous system function. Muscle activation patterns may provide insight into pathological changes compared to healthy controls. To gain a better understanding of surgical interventions, gait muscle activation patterns are studied before and after surgery. Previous studies using surface electromyography have indicated that muscle activation onset, time to peak, and peak amplitude may be helpful in assessing the neuromuscular control strategy that underlies pathological populations. Geometric artifact may influence electromyographic variables as recorded by different electrode types and electrode placement. The purpose of this investigation was to compare surface and fine-wire activation patterns during gait to elucidate the influence electrode type has on electromyographic variables. Lower leg surface and fine-wire electromyographic activity was recorded simultaneously during gait to assess if electrode type (fine-wire vs. surface) affects muscle onset, time to peak, peak amplitude, and activation patterns. No significant differences were recorded between surface and fine-wire electrodes for muscle onset or time to peak activation. Activation patterns revealed similarity between electrodes. Some significant differences were detected in peak amplitude. Non-invasive surface electrodes provide an adequate representation of timing variables for primary ankle muscles during gait.