Evaluation of Lumbar Muscle Activation Patterns during Trunk Movements using High-Density Electromyography: A Preliminary Report.

Lumbar paraspinal muscles are heavily involved in daily and work-related activities including trunk bending, trunk twisting, and lifting. Repetitive or inappropriate activation of the lumbar muscles while performing these activities can lead to low back pain. The aim of this preliminary study was to quantify the activation patterns of multiple lumbar muscles when participants performed three different trunk movement tasks, including sustained lumbar flexion posture, dynamic lumbar flexion and extension, and left-right twisting movements. Two 8×8 high-density electromyogram (HD-EMG) electrode arrays were used to record the lumbar muscle activity during these movements. We observed a symmetric and rapid increase in the amplitude of EMG in the erector spinae muscles during the sustained flexion or oscillation tasks. Asymmetric activation patterns were observed in bilateral lumbar muscles during the trunk twisting task. In addition, we observed substantial bilateral co-activation of the lumbar muscles for both twisting directions. These preliminary results demonstrated the potential feasibility of using HD-EMG as a tool to monitor spatial activation patterns of the lumbar muscles during different trunk movements. This approach can also be further developed to assess lumbar muscle function in individuals with low back pain.