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Licensed Unlicensed Requires Authentication Published by De Gruyter November 2, 2017

Long-term recording of electromyographic activity from multiple muscles to monitor physical activity of participants with or without a neurological disorder

  • Katie Gant , Jorge Bohorquez and Christine K. Thomas EMAIL logo


Various portable monitors have been used to quantify physical activity but most rely on detecting limb movement with a sensor rather than measuring muscle activity. Our first goal was to design and validate a portable system for recording surface electromyographic activity (EMG) from eight muscles over 24 h. The modular system includes: (1) preamplifiers that filter and amplify signals; (2) a preprocessor unit for further filtering and amplification, signal offset and power supply modification; (3) a data-logger for analog-to-digital conversion; a flash memory card for data storage and (4) a rechargeable battery. The equipment samples EMG at 1000 Hz, has a resolution of 2.6 μV and records signals up to 10 mV. The built-in analog filters create a bandwidth appropriate for surface EMG. Our second aim was to test the system biologically by recording EMG from able-bodied and spinal cord injured participants. Modifications were made to electrodes for remote preamplifier placement, and to the battery connection after pilot testing. Thereafter, 31 consecutive 24-h EMG recordings were successful. Both the engineering and biological validation of this system establishes it as a valuable tool for measuring physical activity from different muscles in real-world environments whether individuals have an intact or damaged nervous system.

Corresponding author: Christine K. Thomas, PhD, The Miami Project to Cure Paralysis, University of Miami, 1095 NW 14 Tce, R48, Miami, FL 33136, USA, Phone: +305 243-7109, Fax: +305 243 3913


The authors thank Adriana Martinez, James Atkison and Luis Montoya for help with data collection. This work was supported by the National Institute of Neurological Disorders and Stroke (NS-30226) and The Miami Project to Cure Paralysis.


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Received: 2016-10-12
Accepted: 2017-09-20
Published Online: 2017-11-02
Published in Print: 2019-02-25

©2019 Walter de Gruyter GmbH, Berlin/Boston

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