Effects of a passive back-support exosuit on lumbar muscle activity and passive moment under different harvesting postures and ground slopes

Agriculture workers face a high prevalence of low back pain due to exposure to awkward harvesting postures and sloped surfaces. This study examined how harvesting postures and ground slopes affect the effectiveness of a passive back-support exosuit in reducing lumbar muscle activity and passive moment. Sixteen participants held harvesting trunk postures (kneeling, squatting, stooping) on decline (20°), level (0°), and incline (−20°) surfaces with horizontal hand positions of 0 and 50 cm. Each condition was completed twice with and without the exosuit. Dependent variables were the normalised electromyography of lumbar extensor muscles and passive moments calculated from lumbar flexion angles. Results revealed that the exosuit significantly reduced passive moments during stooping (35.0%) and decreased lumbar muscle activities during kneeling (23.7%) and squatting (27.8%). These effects remained consistent across different ground surfaces. These findings suggest that back-support exoskeletons/suits have potential to reduce low back stress in diverse agricultural harvesting postures.Practitioner Summary Noting differences in active and passive lumbar contributions to trunk extension moment across harvesting postures and ground slopes, this study examined whether a back-support exosuit reduces tissue loads and suggests the exosuit can effectively reduce lumbar muscle activity during kneeling/squatting and passive moment during stooping, with consistent effects across slopes.