Effect of trunk flexion angle and time on lumbar and abdominal muscle activity while wearing a passive back-support exosuit device during simple posture-maintenance tasks

• Published in: Ergonomics Vol. 66; no. 12; pp. 2182 - 2192
• Main Authors: Kang, Sang Hyeon, Mirka, Gary A.
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 02.12.2023; Taylor & Francis LLC
• Subjects: Abbreviations; Abdominal Muscles; Adaptation; adaptation effect; Electromyography; Electromyography - methods; EMG; Exoskeleton; Exoskeletons; exosuit; Fast Fourier transformations; Fourier transforms; Humans; Inertial platforms; Learning; Low back pain; Lumbosacral Region - physiology; Maintenance; Muscle contraction; Muscle Contraction - physiology; Muscle function; Muscle, Skeletal - physiology; Muscles; Posture; Posture - physiology; Rectus Abdominis; Statistical analysis; Support systems; surgery ergonomics; Time dependence; Time of use; Wearable technology; adaptation effect; exosuit; EMG; surgery ergonomics
• ISSN: 0014-0139; 1366-5847
• DOI: 10.1080/00140139.2023.2191908

Quantifying the trunk flexion angles at which wearable support systems (exoskeletons/exosuits) provide substantial trunk extension moment during posture maintenance tasks (such as those seen in surgical environments) can provide a deeper understanding of this potential intervention strategy. Understanding how time (i.e. adaptation/learning) might impact the reliance on wearable support is also of value. Sixteen participants were asked to maintain specific trunk flexion angles (range 0–60°) with and without an exosuit system while erector spinae and rectus abdominis muscle activity were captured using surface electromyography. The effects of the exosuit showed a statistically significant (p < 0.007) effect on the activity of the erector spinae muscles at 10–60°–an effect that became ‘large’ (Cohen's d = 0.84) after 20° of trunk flexion. There were no meaningful time-dependent trends in the levels of muscle activation indicating there was no adaptation/learning effect of the exosuit in the task studied. Practitioner summary: This study examined the effectiveness of a back-support exosuit as a function of trunk flexion angle and time of use. The results revealed that the exosuit significantly reduced erector spinae muscle activity beyond 20° of trunk flexion but did not show a meaningful adaption/learning effect. Abbreviations: LBP: low back pain; EMG: electromyography; NEMG: normalized electromyography; IMU: inertial measurement unit; ES: erector spinae; RA: rectus abdominis; MVC: maximum voluntary contraction; FFT: Fast Fourier Transform.