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Published on: June 12, 2019
Reliability of quadriceps surface electromyography measurements is improved by two vs. single site recordings
T G Balshaw1,2,3, A Fry4, T M Maden-Wilkinson4,5
1School of Sport, Exercise, and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK. t.g.balshaw@lboro.ac.uk.
Purpose:
The reliability of surface electromyography (sEMG) is typically modest even with rigorous methods, and therefore further improvements in sEMG reliability are desirable. This study compared the between-session reliability (both within participant absolute reliability and between-participant relative reliability) of sEMG amplitude from single vs. average of two distinct recording sites, for individual muscle (IM) and whole quadriceps (WQ) measures during voluntary and evoked contractions.
Methods:
Healthy males (n = 20) performed unilateral isometric knee extension contractions: voluntary maximum and submaximum (60%), as well as evoked twitch contractions on two separate days. sEMG was recorded from two distinct sites on each superficial quadriceps muscle.
Results:
Averaging two recording sites vs. using single site measures improved reliability for IM and WQ measurements during voluntary (16-26% reduction in within-participant coefficient of variation, CVW) and evoked contractions (40-56% reduction in CVW).
Conclusions:
For sEMG measurements from large muscles, averaging the recording of two distinct sites is recommended as it improves within-participant reliability. This improved sensitivity has application to clinical and research measurement of sEMG amplitude.
