Mechanomyography energy decreases during muscular fatigue in paraplegics

• Published in: 2014 36th Annual International Conference of the IEEE Engineering in Medicine and Biology Society Vol. 2014; pp. 5824 - 5827
• Main Authors: Krueger, Eddy, Scheeren, Eduardo M., Nogueira-Neto, Guilherme N., Nohama, Percy
• Format: Conference Proceeding Journal Article
• Language: English
• Published: United States IEEE 01.01.2014
• Subjects: Adult; Electric Stimulation; Energy Metabolism; Fatigue; Force; Frequency modulation; Humans; Muscle Fatigue; Muscle Strength; Myography; Neuromuscular; Paraplegia - physiopathology; Protocols; Quadriceps Muscle - physiopathology; Spinal Cord Injuries - physiopathology; Spinal cord injury; Young Adult
• ISSN: 1094-687X; 1557-170X
• DOI: 10.1109/EMBC.2014.6944952

The present work investigated the response of triaxial MMG signals acquired from the rectus femoris muscle of spinal cord injured volunteers during fatigue protocol electrically evoked. A custom functional electrical stimulator voltage-controlled was configured as: pulse frequency set to 1 kHz (20% duty cycle) and burst (modulating) frequency set to 70 Hz (20% active period). The triaxial MMG signal of rectus femoris muscle was processed with third-order 5-50 Hz bandpass Butterworth filter and the values were normalized. A load cell was used to register the force. The stimulator output voltage was increased until the maximal electrically-evoked extension (MEEE) of knee joint. After the load cell placement, the stimuli magnitude required to reach the MEEE was applied and registered by the load cell as muscular force-100% response. Stimuli intensity was increased until and during the control to keep the force in force-100%. Four instants with force functional electrical stimulation (FES)-controlled were selected between force-100% and slope down to force-30%. The MMG energy decreased with FES application due neuromuscular fatigue in paraplegic subjects. X-axis between instant I (1 ± 0) and instant IV (0.74 ±0.27), and the same tendency was found to Y-axis between instant II (1.14 ± 0.44) and instant IV (0.91 ± 0.3).