Ergonomics plays an important role in the prevention of strains, injuries, and repetitive motion disorders. One of the first professional societies in the field of ergonomics was the Ergonomics Research Society in the United Kingdom, which was started in 1949. There are numerous and varied subdisciplines within the field of ergonomics. This chapter will focus primarily on the National Institute for Occupational Safety and Health (NIOSH) Lifting Equation. The Recommended Weight Limit (RWL) is the primary product in the NIOSH lifting equation. It is defined for a specific set of task conditions as the weight of the load that nearly all healthy workers could perform over a substantial period without an increased risk of developing lifting-related low back pain or injury. The lifting equation is a tool for assessing the physical stress of two-handed manual lifting tasks. Specifically, the lifting equation was designed to meet specific lifting-related criteria that encompass biomechanical, work physiology, and psychophysical assumptions and data.