Reducing awkward postures
Where awkward postures are highlighted as a problem, this is often due to poor workstation and equipment design or selection. The general principles for reducing awkward postures are to:
- Enable work to be done with the joints at about the mid points of their range of motion
- Reduce the time spent holding and/or repeating awkward postures
- Avoid using static postures for prolonged periods
Consider the location, angles and height of equipment, controls or work pieces in relation to the worker. Modify these to improve posture.
Ensure workplaces and work equipment are designed or selected to account for difference in size, shape and strength of workers.
Alter tool design to improve wrist posture.
Can changes be made 'upstream' of the task? ie does the task really have to be like this, or can alterations in the process elsewhere mean that items do not have to be assembled or presented in this way?
Can the sequence of actions be changed to make the task less awkward?
Alter tool design to improve wrist and hand posture (to enable a straight wrist posture and power hand grip).
When selecting tools, a trial period with several workers is recommended.
Ensure purchasers have some knowledge of the task for which the tool will be used.
Ensure it is possible to use the tools in either hand, or provide a specific tool for left handed workers.
Consider differences in male and female hand size and the effects of wearing gloves.
Presentation / orientation of work items
Consider the position of the work, and the use of fixtures and jigs to angle and hold work in more accessible positions.
Consider how the body will interface with the equipment.
Are there objects or attachments that act as obstacles and lead to poor posture?
Ensure seats are adjustable.
Ensure that there is sufficient space to enable workers to make effective use of the adjustable features of their chairs.
Do workers know how to adjust their chairs?
Ensure that there is sufficient leg space for the worker to stretch and make changes in leg and foot posture. Confined leg space can constrain overall body posture.
Place equipment and materials within primary reach zones keeping repetitive reaching as close as possible to the body and always within 450 mm of the front of the operator.
Further information on reach distances can be found in Conveyor belt workstation design.
Can the height, angle and position at which the work is being conducted be changed to improve visibility of the task?
Tables should accommodate the largest users. Platforms, adjustable chairs and footrests can be used by smaller users to achieve optimal working height.
Should be used for jobs that require a lot of body movement and greater force.
The most suitable working height depends upon the nature of the task being performed.
(Involving a moderate degree of both force and precision): table height should be 50-100 mm below elbow height.
(Including writing): table height should be 50-100 mm above elbow height.
(Particularly if they involve downward pressure to be applied on the work piece): table height should be from 00-250mm below elbow height.
These general guidelines can be applied to both seated and standing work tasks. It is recommended that adjustable height surfaces be provided wherever possible, due to differences in elbow height and task characteristics.