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

• Published in: Biomedizinische Technik Vol. 64; no. 1; pp. 81 - 91
• Main Authors: Gant, Katie, Bohorquez, Jorge, Thomas, Christine K.
• Format: Journal Article
• Language: English; German
• Published: Germany De Gruyter 25.02.2019; Walter de Gruyter GmbH
• Subjects: Amplification; Analog to digital conversion; Analogue filters; Batteries; Data storage; Electromyography; Exercise; Flash memory (computers); Modular systems; Motion perception; Muscles; Nervous system; Neurological diseases; Physical activity; portable recordings; Power supplies; Preamplifiers; Rechargeable batteries; Recording; Spinal cord injuries; spinal cord injury; spinal cord injury; portable recordings; physical activity
• ISSN: 0013-5585; 1862-278X
• DOI: 10.1515/bmt-2017-0104

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.