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Updated: Feb 1, 2026

Muscle Function Obtained with Motion Mode Ultrasound and Surface Electromyography during Core Endurance Exercise
Published on: August 25, 2022
Differences in muscle contraction onset as determined by ultrasound and electromyography
Andrew J Tweedell1, Matthew S Tenan2, Courtney A Haynes1
1United States Army Research Laboratory, Human Research and Engineering Directorate, 459 Mulberry Point Road, Aberdeen Proving Ground, Maryland, USA.
Introduction:
We characterize the agreement between the timing of muscle contraction onset detected by surface electromyography (sEMG), fine wire EMG (fwEMG), and motion-mode (M-mode) ultrasound for improved interpretations of clinical outcomes.
Methods:
Eighteen healthy adults participated. Differences in contraction onset were compared between sEMG, fwEMG, and M-mode ultrasound collected during concentric contractions of the vastus lateralis and biceps brachii.
Results:
The mean difference of 13.1 ms (-33.3-59.9) between sEMG and fwEMG was non-significant (intraclass correlation [ICC] = 0.60). Ultrasound was significantly different from surface and fine wire EMG (ICC = 0.65 and ICC = 0.40, respectively), occurring 98.6 ms (72.3-124.9) and 111.7 (60.3-163.0) before sEMG and fwEMG, respectively. Nonparametric interquartile ranges were also wide.
Conclusions:
Due to high variability, comparisons between EMG methods should be interpreted with caution. Ultrasound detected onset before either EMG method, which may indicate motion from adjacent muscles during voluntary contractions. Muscle Nerve 59:494-500, 2019.
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