Back Support Exoskeletons Ease Muscle Strain, but Metrics Tell Different Stories

Passive back support exoskeletons (BSEs) are designed to reduce stress on the lumbar spine and alleviate low back pain, but most studies evaluating their effectiveness have relied on a single easily measured outcome: muscle activation. A new study asked whether that reliance is justified, examining whether changes in back muscle activity during load handling actually reflect estimated forces at the L5–S1 spinal joint and how strenuous the task feels to the wearer. Researchers tested 12 healthy young adults performing lifting and lowering tasks while wearing a passive BSE.

The device significantly reduced average activation of the thoracic erector spinae muscles during both lifting and lowering, and reduced lumbar erector spinae activation during lowering. Integrated thoracic erector spinae activation also fell during lowering, indicating a meaningful reduction in overall muscle demand for those conditions. The biomechanical benefits extended beyond the muscles.

Estimated L5–S1 joint reaction forces were significantly reduced when participants wore the exoskeleton, with the reduction reaching statistical significance at p < 0.001. Participants also reported a lower rate of perceived exertion, meaning the tasks felt less strenuous, at p < 0.05. Despite these consistent improvements across all three categories of measurement, the study found no significant associations among the metrics.

Reductions in muscle activation did not reliably predict reductions in estimated spinal joint loading, and neither measure tracked closely with participants' subjective perceptions of effort. The authors conclude that inferring one measure from another remains limited when evaluating how well a BSE performs. The findings suggest that a single outcome measure, however convenient, may paint an incomplete picture of exoskeleton effectiveness.

Subject of Research: Effects of passive back support exoskeletons on muscle activation, spinal joint loading, and perceived exertion during lifting

Article Title: Dissociation between muscle activation, spinal joint load, and subjective perception in passive back support exoskeleton use

Article References: Jung, H., Ahn, J., Choi, E., Moon, J., Kong, K., & Ahn, J. (2026). Dissociation between muscle activation, spinal joint load, and subjective perception in passive back support exoskeleton use. PLOS One, 21(10), e0361338. https://doi.org/10.1371/journal.pone.0361338

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0361338

Keywords: back support exoskeleton, L5-S1 joint reaction force, erector spinae, muscle activation, perceived exertion, lifting, lumbar spine, biomechanics, wearable robotics, occupational health, Dissociation, between