Effects of Back-Support Exoskeletons on Low Back Muscle Activity and Trunk Posture Associated with Simulated Manual Timber Felling

Manual timber felling involves sustained trunk flexion, causing substantial strain on the low back. Although passive back-support exoskeletons (BSEs) have been shown to reduce low back strain in industrial settings, their effectiveness during timber felling remains unclear. This repeatedmeasures laboratory study examined the effects of two passive BSEs on trunk flexion and low back muscle activity in 20 male participants performing simulated timber felling at three cutting heights (low, medium, high), with and without exoskeletons. Results indicated that BSEs significantly influenced trunk flexion and muscle activity, but their effectiveness varied by cutting height. BSEs were most effective at the medium height, where trunk flexion was greatest. In contrast, limited effects were observed at the low and high heights, where reduced trunk flexion may have limited engagement of the exoskeletons’ supportive mechanisms. These findings underscore the importance of task-specific exoskeleton selection to ensure alignment between support function and actual working posture.