Xueqing Zhou’s MSc Thesis Proposal

Title: Pelvic floor muscle activation patters during exoskeleton-assisted walking in individuals with motor-complete spinal cord injury

Supervisors: Drs. Tania Lam & Jean-Sébastien Blouin
Committee member: Dr. John Kramer

Background: The pelvic floor muscles (PFM) have an important role in maintaining continence, and are a potential therapeutic target for improving bladder function after spinal cord injury (SCI). The PFM can be contracted voluntarily in isolation, or co-activated with their synergistic muscles in the abdominopelvic region during different abdominal maneuvers and dynamic activities (e.g., locomotion). Individuals with motor-complete SCI were shown to have preserved cortical innervation to the PFM, and were able to activate the PFM during maneuvers that also engaged the trunk muscles. However, pelvic floor activation during locomotion (i.e., exoskeleton-assisted locomotor training) has not been examined in this population. Previous research also demonstrated higher trunk muscle activation during walking in the Ekso than Lokomat in people with motor-complete SCI, likely related to the greater demand on weight shifting during Ekso-assisted walking when compared to the passive, automated propulsion in the Lokomat. Considering the synergistic relationship between the PFM and abdominal muscles, whether the Ekso is more effective than the Lokomat in engaging the PFM is worth investigating.

Objectives: To (1) characterize and compare pelvic floor activation patterns during walking in the Lokomat and Ekso in people with motor-complete SCI, and (2) explore the co-activation pattern between the PFM and their synergists, as well as the effect of pelvis acceleration on pelvic floor activation, during exoskeleton-assisted walking in this population.

Methods: We aim to recruit 8 participants with motor-complete SCI for this within-subject cross-sectional study. We will obtain bilateral surface electromyography (EMG) recordings from the PFM and their synergists, alongside with pelvis accelerometry data, during walking in the Lokomat and Ekso at matched (1km/h) and self-selected maximum speeds. We will quantify the amplitudes and timing (number, onset, and duration of bursts) of pelvic floor and synergistic muscle EMG, and pelvis acceleration in all three axes with respect to the gait cycle. 2×2 repeated-measures ANOVA (device × speed) and one-way repeated-measures ANCOVA (Lokomat vs. Ekso with pelvis acceleration as a covariate) will be used for statistical analysis.