Surface electrode placement affects the EMG recordings of the quadriceps muscles

Wong, Yiu-Ming; Ng, Gabriel Y.F.

doi:10.1016/j.ptsp.2006.03.006

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Volume 7, Issue 3 , Pages 122-127, August 2006

Surface electrode placement affects the EMG recordings of the quadriceps muscles

Orthopaedic Rehabilitation Research and Microscopy Laboratory, Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong

Received 3 November 2005; received in revised form 17 March 2006; accepted 27 March 2006.

Abstract

Objectives

This study examined the EMG activities of the medial and lateral vasti muscles with four different surface electrode positions during isometric knee extension and knee perturbation.

Design

Repeated measures design.

Setting

Orthopaedic rehabilitation laboratory of a university.

Participants

Eight able-bodied non-athletic male volunteers.

Main outcome measures

The relative onset time difference in milliseconds of vastus medialis obliquus (VMO) and vastus lateralis (VL) during knee perturbation, and the normalized EMG amplitude in root-mean-square ratio of VMO:VL during submaximal isometric knee extension were analyzed using repeated measures ANOVA.

Results

Different electrode positions on VL resulted in different VMO-VL onset time () and normalized VMO:VL activity ratios (, 0.014).

Conclusions

The position of surface electrodes has significantly affected the EMG readings of the vasti muscles. This finding has vital clinical implications for the application of EMG measurement and biofeedback training for the rehabilitation of the vasti muscles.

Keywords: Electromyography, Electrode, Knee, Quadriceps muscle