Lumbar Compression and Shear Loading during Simulated Fireground Operations

Together with 3D kinematics of the lower extremities, pelvis, and lumbar spine, ground reaction forces (GRF) and surface EMG signals from the following bilateral trunk muscle groups were recorded: external and internal abdominal obliques; rectus abdominus; lumbar and thoracic erector spinae; and latissimus dorsi. Kinematic and GRF data were incorporated in a “bottom-up” inverse dynamical linked-segment model to yield estimates of L4/L5 net reaction forces and moments (performed in Visual3DTM, C-Motion, Inc.). These kinetic quantities were then input with normalized EMG data into a musculoskeletal model of the torso [1] to compute peak L4/L5 joint compression and shear forces during task performance. The general data acquisition, signal processing, and EMG-toforce modeling procedures are described elsewhere [2].