Ergonomic considerations with push and pull activities

Failing to take ergonomics into account in many workplace situations can result in injuries, be they immediate or ones that develop over time.
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Nowhere is this truer than in tasks that require pushing and pulling. An employee holding a heavy object incorrectly or positioning themselves poorly can have devastating consequences that can leave them in the emergency room and recovering for weeks, or longer. Here's how to avoid that kind of grim scenario.

Equipment and other aids
The first thing you need to consider is designing work to control the amount of pushing or pulling an employee is expected to do.  

For example, you can set a limit on the number of shopping carts a worker is expected to collect from the parking lot in one trip.

When possible, you can limit the need for pushing or pulling by using applicable mechanical aids. Depending on the environment, these might include:

• Conveyer belts
• Powered trucks
• Lift tables
• Slides or chutes

 
The force required to push or pull can be lowered by reducing the size or weight of a load or using a four-wheel truck or dolly. 

Proper selection and maintenance of hand-trucks and dollies is important to reduce breakdowns and accidents. 

Wheels or casters should be adequately maintained, and bearings should be lubricated periodically. Be sure that the equipment is properly sized for the task, such as with larger diameter wheels and casters for heavier loads.
 
Floors
Floors also affect the ergonomics of pushing and pulling.  Floors that are not level increase the difficulty of pushing or pulling, as do floors that are rough. 

Maintaining floors and applying a surface treatment that reduces friction may be advisable.
 
Reduce distances
Reducing the distance of the push or pull is an easy way to improve the ergonomics. 

Two examples would be moving receiving, storage, production, or shipping areas closer to work production areas, and changing the production process to eliminate unnecessary materials-handling steps.
 
Optimize the tasks
The actions of pushing and pulling can be optimized by:

• Providing variable-height handles so that both short and tall employees can maintain an elbow bend of 80 to 100 degrees,
• Replacing a pull with a push whenever possible, and
• Using ramps with a slope of less than 10%.

 
Keep in mind that a number of factors influence the ergonomics of horizontal pushing and pulling, such as:

• Body weight,
• Height of force application,
• Distance of force application from body (amount of trunk flexion/extension),
• Duration of force applied or distance moved, and
• Availability of a structure against which the feet or back can push to prevent slippage. 

 
Vertical pushing and pulling
Grip strength and height of force application are the most influential factors when pushing and pulling vertically.

The height determines which muscles will be used. Pulls from above head level allow for the greatest force because body weight can be used.

Pulls from more than 10 inches above the floor also allow the greatest force because strong leg and trunk muscles can be used. 

Pushing across the front of the body involves weaker shoulder muscles. Full arm extension leads to a marked decrease in maximum force, which can result in injury.
 
The takeaway
Tasks that require pushing and pulling can be vertical or horizontal in nature and they have their own unique dangers for your workers.
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By focusing on the ergonomics of the tasks, you can train your staff to carry out their duties and reduce their risk of injury.