Effects of a Passive Back-Support Exosuit on Objective and Subjective Measures of Human Performance During a Simulated Bush-Crop Harvesting Task
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2025-02-23
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Taylor and Francis
Abstract
Objective: Interest in wearable passive back-supports (exoskeletons/suits) has grown rapidly as a tool to reduce the risk of low back injury by reducing lumbar extensor muscle loading. Previous studies have shown the effectiveness of passive back-support exoskeleton/suit at reducing low back muscle activity/fatigue in a variety of tasks, but it is unclear whether an exoskeleton/exosuit intervention would be effective in agricultural harvesting tasks that require complex three-dimensional dynamic motions, long duration stooped postures, and variable engagement of the lower extremities. The objective of the current study was to evaluate the effects of a passive lumbar support exosuit on muscle fatigue and comfort/mobility during a simulated harvesting task in a controlled laboratory setting. Methods: Sixteen participants were asked to perform a continuous work task that simulated a three-minute bout of harvesting from a bush crop. Participants harvested at a rate of 1 per two seconds (i.e., 0.5 units per second) and were permitted to assume any effective harvesting position except a full kneeling posture. Each participant completed four harvesting trials: two repetitions both with and without the support of the exosuit. Test contractions and subjective assessments were performed before and after each three-minute bout of a simulated harvesting task to allow for an assessment of the 1) changes in objective measures of erector spinae muscle fatigue development (both time domain and frequency domain measures of muscle fatigue) and 2) subjective measures of physical fatigue, and 3) exosuit comfort and mobility constraints. Results: The exosuit significantly mitigated the increases in EMG amplitude in the time domain (p = 0.015; Cohen’s d = 0.46) indicating a mitigation of muscle fatigue, but there was no significant exosuit effect on median frequency (p = 0.145) or perceived fatigue in the low back (p = 0.289). In addition, the exosuit use was associated with significant increases in perceived movement restriction (p < 0.001; d = 0.82) which were also manifested in terms of significant effects of the exosuit on the magnitude of the 90th percentile of the trunk flexion (p = 0.027, d = 0.29). Conclusion: The results of this study demonstrated moderate muscle fatigue reduction effects at the cost of a negative impact on objective and subjective measures of trunk motion restrictions and comfort.
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This is an Accepted Manuscript of an article published by Taylor & Francis as Kang, Sang Hyeon, Emma Wolf, Luke Lowe, and Gary A. Mirka. "Effects of a Passive Back-Support Exosuit on Objective and Subjective Measures of Human Performance During a Simulated Bush-Crop Harvesting Task." Journal of Agromedicine (2025): 1-12.
doi: https://doi.org/10.1080/1059924X.2025.2470257.
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This manuscript is deposited under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited.