Methods of Using the Lifting Fatigue Failure Tool (LiFFT) as an Ergonomic Assessment Tool in the Commercial Production of Turkey Eggs

Several manual lifting evaluation tools are currently available to analyze mono-task jobs, yet most jobs involve multiple varying tasks. Therefore, a summation of mono-task analysis may not be an accurate representation of the degree of compressive forces and stress placed on the spine. The Lifting Fatigue Failure Tool (LiFFT) has been adapted from the fatigue failure theory (FFT) and is capable of both mono-task and cumulative task evaluation. The FFT details cumulative damage of the applied stress and the number of cycles to failure, therefore calculating a representative spinal compression is important in applying the corresponding limits. The original Gallagher method only requires three variables to use the LiFFT: the weight of the load, horizontal distance, and repetition per day. Other methods of applying the tool have emerged to achieve a more accurate calculation of spinal compression. The Potvin method includes a vertical height of the load and the 3DSSPP method uses digital human modeling (DHM) to calculate spine compression. The objective of this study was to compare the different methods of calculating spine compression for entry into the LiFFT to determine the variance in outputs. The results showed that the Gallagher method is best suited for lifts that do not require significant vertical postural changes whereas the Potvin and 3DSSPP methods are able to assess more complex lifts. Although DHM is the gold standard, the Potvin method is preferred for practitioners due to its ease of use. Overall, the LiFFT is a practical, effective, and practitioner friendly tool capable of predicting the risk about the low back in simple and complex manual lift evaluations.