• Author / Creator
    Claveria-Gonzalez, Francisca C
  • Neuromuscular electrical stimulation (NMES) can produce contractions of paralyzed muscles to improve function and reduce secondary complications for individuals with a spinal cord injury (SCI). NMES is typically delivered through a single pair of electrodes over a muscle belly at a stimulation frequency of ~40 Hz, which in this thesis will be referred to as conventional NMES, and its’ benefits are limited by rapid contraction fatigability. Therefore, the present study compared three NMES approaches including NMES over the femoral nerve (NERVE), NMES rotated between four electrodes over the muscle belly (sequential NMES; SEQ) and hybrid NMES (HYBRID) which combines NERVE and SEQ NMES to determine which type of NMES produces the most fatigue resistant contractions of the quadriceps muscle. In addition, we assessed variability between consecutive contractions and discomfort (Visual Analogue Scale; VAS) associated with the stimulation. Fourteen healthy human participants (10 males and 4 females; 27±8 years) were recruited. The 3 types of NMES were tested in different sessions on separate days. Each session incorporated a fatigue protocol consisting of 180 contractions (0.3s "on", 0.7s "off"; 40 Hz). Fatigability was quantified as the decrease in evoked torque over time. There were no differences in contraction fatigability between the three NMES types; torque declined by 17±34%, 30±12%, and 31±17% for NERVE, SEQ and HYBRID, respectively. SEQ resulted in the least variability between successive contractions (2.9±2.9 %). NERVE produced the most variability between contractions and least discomfort (VAS = 23±14 mm). As there was no difference in the amount of fatigability between the three protocols, and NERVE and SEQ have resulted in less fatigability than conventional NMES, we suggest that all three types of NMES studied in this thesis produced less contraction fatigability than is typical of conventional NMES. As there was no clear difference in fatigability between the three protocols, and given the practical issues with delivering NMES over the femoral nerve, which affects both the NERVE and HYBRID protocols in the present study, we suggest SEQ to be incorporated into clinical practice. SEQ has consistently shown to reduce fatigability compared to conventional NMES (Bergquist, Babbar, Ali, Popovic, & Masani, 2016; Downey, Bellman, Kawai, Gregory, & Dixon, 2015; Maneski, Malesevic, Savic, Keller, & Popovic, 2013; Nguyen, Masani, Micera, Morari, & Popovic, 2011; Popovic & Malesevic, 2009; Sayenko, Nguyen, Hirabayashi, Popovic, & Masani, 2015; Sayenko, Nguyen, Popovic, & Masani, 2014), is easy to apply and the torque generated is consistent between evoked contractions, hence it could be easily incorporated in clinical settings.

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    Master of Science
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    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.