Lifting and carrying are the two material handling tasks that result in the greatest number of worker injuries each year. (See our May 14 post on tips for ergonomic carrying.) Applying ergonomics to material handling tasks that involve lifting reduces the need for reaching and bending and the injury-producing stress those actions can place on the back and shoulders. Ergonomics also strives to reduce the amount of effort and force necessary to perform lift tasks.
Calculations of lift force involve both the amount of weight to be lifted and the time period over which the average worker can lift that weight without risk of developing lower back pain. Under ideal conditions, the maximum weight a typical healthy worker can lift with two hands over an 8-hour period is 51 pounds, according to the National Institute of Occupational Safety and Health (NIOSH). However, a number of variables can significantly reduce the maximum lift weight.
To decrease the potential risk of injury from lift tasks, both overall work flow and individual work tasks should be evaluated to eliminate unnecessary lifting. Where lifting is necessary, ergonomically designed equipment can be used to facilitate many lift tasks. Workers can also be trained to use ergonomic principles in performing lift tasks to minimize potential injury.
To decrease injuries caused by lifting, follow these suggestions:
- Use ergonomic electric scissor lift tables and power hoists to lift and lower loads where possible to minimize manual lifting.
- Minimize the distance materials must be lifted or lowered.
- Use adjustable powered tugs that allow workers to position lift loads at the appropriate height for maximum lifting power.
- Tag unstable or heavy loads to alert workers. Promote team lifting of such loads to minimize potential worker injury.
- Test loads for weight and stability before lifting.
- Reduce load weights and balance loads to facilitate lifting without injury.
- Rotate workers between lifting and non-lifting tasks or have workers alternate lifting with non-lifting tasks to avoid over-straining muscles.
- Reduce the frequency of lifting and amount of time workers perform lifting tasks.
- Provide clear access to materials to be lifted to prevent awkward reaching, bending and twisting during lifting.
- Provide secure grips on materials to be lifted.
- Provide sufficient foot traction with the floor to increase worker stability during lifting.