By R. Daniel Muñoz, AEP
Often ergonomists get asked, “How much can someone lift or push?” while working in a material handling environment. The answer to this depends on a number of things including the force exerted while performing the task, the frequency at which the task is performed, and the location of the hands in relation to the body. There is one publicly available tool that is widely used to measure weight limits given a specific task—the NIOSH Lifting Equation.
The NIOSH Lifting Equation allows you to calculate a recommended weight limit for a lifting scenario based on the conditions of the lift. This recommended weight limit is then compared to the actual weight lifted to produce a ratio called the Lifting Index. Ideally, this ratio would be ≤1:1 (lifting the same or less than the recommended weight limit).
Here are some things you can do to improve your Lifting Index:
Reduce horizontal reach
- Implement rotating rings for pallets
- Reduce conveyor and table widths
- Slant surfaces to bring objects close to the edge of the workstation
Improve vertical height
- Implement height-adjustable equipment to keep items in the “comfort zone”
- Limit stacking heights
- Place heavier objects on the middle shelves
- Provide at least 50″ between the start and the end of the lift to encourage employees to take an additional step, aligning their hips and shoulders
- Ensure objects lifted have optimal handles which enable employees to use power grips (overlapping the thumb with any of the other fingers while grasping)