Influence of Spring Loaded Passive Exoskeleton on Erector Spinae Muscle Activity in Mathadi Workers with and without Low Back Pain

Mathadi workers carry a load on the head (Matha), back, neck and or shoulders and stack it at appropriate place. High prevalence of low back pain and musculo-skeletal injuries caused by manual material handling and lifting heavy-weights and prolonged stooped postures has prompted research interest in novel orthotic solutions to improve occupational health of manual workers worldwide. Hence, present study aimed to develop a novel spring-loaded, wearable passive exoskeleton to reduce trunk muscle activity and prolong muscle fatigue in Mathadi workers. A passive-spring- loaded spine- exoskeleton was developed using a shoulder harness, lumbar corset and spring. The stiffness of spring (114N) was determined in quiet stance with 3 different weights using surface-EMG(S-EMG). Following ethical approval, spine-exoskeleton was tested in 20 Mathadi workers; 10 workers with low back pain(LBP) and 10 workers without LBP after signed informed consent. Trunk muscle activity was recorded using S-EMG of lumbar erector spinae during Sorensen's trunk holding test with and without exoskeleton. Median frequency was recorded to indicate muscle fatigue. Both groups demonstrated 24% increase in median frequency (MF) of erector spinae muscle when using exoskeleton compared to performing the test without exoskeleton (p< 0.05) during Sorensen fatigue test, suggesting reduced trunk muscle activity. Increased median frequency with spring-loaded passive exoskeleton indicated reduced muscle fatigue of the lumbar erector spinae muscles in Mathadi workers with and without low back pain during fatiguing tasks. Further studies are ongoing to design ergonomically sound solution which integrates trunk muscle training and mechanically efficient ergonomic measures with spine- exoskeleton to minimize musculo-skeletal stress.