Systematic ergonomic evaluation of an active back-support exoskeleton

Currently, ergonomic risk assessments for manual material handling rely on the NIOSH lifting equation, which predates the development of exoskeletons and therefore does not account for their potential benefits. To address this limitation, this study proposes an integrated methodology that combines the Equivalent Weight (EqW) approach, which quantifies reductions in muscular effort, with AzKNIOSH, a motion capture-based tool for assessing postural risk through the NIOSH lifting equation. The aim of the study is to objectively evaluate the ergonomic impact of StreamEXO, an active back-support exoskeleton, during manual material handling (MMH) tasks. Fifteen participants performed eight different MMH tasks in a controlled laboratory setting using 5 kg and 10 kg loads. Results show that StreamEXO use leads to statistically significant ergonomic improvements through two mechanisms: a 16 ± 7% reduction in perceived load, as captured by EMG-derived EqW values, and a 23% average improvement in posture, captured by the Kinematic Multiplier (KM), primarily due to reduced horizontal distances to the load. When considered together, these effects result in a 34% reduction in the overall Lifting Index (LI). Additionally, risk exposure decreased by at least one class in 45% of the assessed tasks demonstrating the benefits of StreamEXO in terms of risk exposure.