Effects of back-support passive exoskeletons on biomechanical loads and postural stability during simulated manual timber felling

This study evaluated the effects of passive back-support exoskeletons (BSEs) on biomechanical load and postural stability during simulated manual timber felling at three cutting heights. Twenty healthy adult male participants performed timber felling tasks under four BSE conditions (two rigid, one soft, and no BSE). During the tasks, electromyographic (EMG) activity, trunk angle, postural sway, and perceived exertion were measured. Results showed that rigid BSEs reduced trunk flexion and low back EMG activity at the middle cutting height, where trunk flexion was greatest. No significant changes were observed at low or high cutting heights, likely due to insufficient exoskeleton engagement. BSE use shifted postural control strategies rather than providing a uniform stabilizing effect. Additionally, BSEs lowered perceived exertion for the whole body and low back. These findings suggest that BSEs may help reduce low back loading at the middle cutting height during manual timber felling, but further field testing is warranted.