RESUMO
OBJECTIVE: The aim of this study is to determine the effectiveness of using a leg support exoskeleton (legX) in different modes on simulated work tasks which emulate real-world job tasks. BACKGROUND: Prolonged kneeling and squatting tasks increase the risk of work-related musculoskeletal disorders at the knee in industrial occupations. METHODS: We evaluated legX capable of spring assistance throughout one's range of motion and/or locking support at a fixed angular position. Participants performed a dynamic panel task, alternating between hip and knee height, and a sustained floor level task with and without the exoskeleton. The exoskeleton was evaluated in spring mode, locking mode, and spring + locking mode for the panel task and only in locking mode for the floor task. The participants' (N = 15) muscle activity was recorded for the right lumbar erector spinae, thoracic erector spinae, tibialis anterior, rectus femoris, semitendinosus, and lateral gastrocnemius. RESULTS: Significant reduction of the rectus femoris activity was observed with the exoskeleton (median reduction: 22%-56% and peak reduction: 12%-48% for the panel task and median reduction: 57% and peak reduction:34% during the floor task). CONCLUSION: legX significantly reduces rectus femoris activity during squatted static (floor) and dynamic (panel) work and may reduce pain and discomfort associated with squatting and potentially reduce the risk of developing knee disorders. Dynamic tasks benefit from both locking modes and spring assistance, the greatest benefit occurring with a combination of the two. APPLICATION: These results show that the legX can be beneficial to activities such as electrical panel work, grinding, sanding of larger surfaces, and concrete laying.