Low Back Biomechanics of Keg Handling Using Inertial Measurement Units

Workers handling beer kegs experience risk factors associated with occupational low back pain (heavy loads, awkward trunk postures). Many breweries are small and lack resources for materials handling equipment, causing much work to be done manually (including keg handling). Measuring worker motions (kinematics) may aid job design to reduce risk factors associated with lifting. Low back motions may be evaluated using observation techniques and devices which are oftentimes inconvenient in the field. Application of wireless inertial measurement units (IMUs) for human motion provides whole body kinematics information, including low back. The present study used a 3-dimensional motion capture system to investigate low back kinematics during keg handling at a Colorado brewery. Specifically, five workers lifted spent kegs onto a clean and fill line. Workers wore 17 IMUs as they handled kegs. Low back angular displacements were assessed during keg handling at two heights (low, high). Repeated measures analyses were performed with each trunk angular displacement variable as a function of lift condition. Differences in low back kinematics between lift conditions were identified. During low lifts, torso flexion was significantly greater than high lifts. A broader range of angular displacements was observed in high lifts. Data collection was feasible during operational hours due to IMU's small design. Data collected from experienced workers provided researchers with information directly applicable to keg handling in small breweries. Results from the study can help improve workplace design in a craft brewery, reduce risk, and create safer work.