Ergonomics
Awkward Postures
Awkward postures occur when employees work with various parts of the body in bent, extended, or flexed positions rather than in straight or neutral positions.
Working in awkward postures increases the exertion and muscle force workers must apply to complete a task, and it compresses tendons, nerves, and blood vessels.
In general, the more extreme the posture, the more force is needed to complete the task. Examples of awkward postures include performing overhead work, bending or twisting to lift an object, typing with bent wrists, and squatting or crouching.
Bending the Elbow
~ Repetitive elbow bending irritates nerves and tendons in the forearms.
~ When possible, use machinery or tools to reduce stress on the elbow.
Bent Wrists
~ Prevent inflammation in the tendons of the wrist.
~ Use bent or angled handles and hand-holds that allow work to be done with straight wrists.
Contact Stress/Trauma
Contact stress results from the continuous contact or rubbing between hard or sharp objects/surfaces and sensitive body tissue, such as the soft tissue of the fingers, palms, thighs, and feet. This contact creates localized pressure for a small area of the body, which can inhibit blood flow, nerve function, or the movement of tendons and muscles.
Contact stress can be caused by:
~ prolonged use of tools that vibrate, which can cause contact trauma in the palms and fingers, and
~ standing for long periods of time, which increases the "static load" placed on the legs and back.
Circulation is reduced, blood pools, and localized fatigue increases the longer employees must stand.
Muscles and tendons become more susceptible to strain as they become fatigued from prolonged
standing.
To reduce contact stress:
~ use electric or power tools
~ attach well-designed handles to tools
~ wrap or coat tool handles and grips with cushioning material
~ use palm pads
~ use sit or stand stools to reduce the static loading on the legs and back, and
~ wear shoes with thick or cushioned soles.
Crouching and Kneeling
Some workers must frequently bend or crouch to reach the workspace or to lift materials. This kind of activity can contribute to poor circulation when a crouched position is maintained. It may injure the knees if workers are maintaining a kneeling position where the knees come in contact with the floor.
Cumulative Trauma Disorder
Cumulative Trauma Disorders (CTDs) and Repetitive Motion Injuries (RMIs):
~ Result of continued stress on specific joints, tendons, and muscles
~ Can be controlled
The earlier CTDs and RMIs are identified
and treated, the more likely you are
to prevent a serious disability.
Risk Factors
~ Frequent repetitive movements
~ Great force or intensity used
~ Poor posture and body position
~ Improper workstation or environment
High Hand Force
High hand force (gripping or squeezing) can cause muscle fatigue, tendon inflammation, and contact trauma.
Weight of hand tool – The heavier the tool, the more force is required.
Size of hand tool – Tools with good weight distribution are easier to hold and handle.
Handle or grip size – Tool handles that are too small or too big reduce the employee’s grip efficiency, requiring more force and exertion to hold and use the tool.
Tool activation – The way tools are activated can also increase the amount of hand force employees must exert.
~ Tools with squeeze triggers, such as scissors and staple guns, may require employees to apply a lot of
muscle contraction in the hand and fingers, especially if the object to be cut is thick or dense.
~ If the trigger of a tool is too small, the employee may only be able to use one finger to activate it.
Where all the force to squeeze the activation trigger must be generated by one finger, the tendons may
be overused to the point where fluid builds up, making it difficult to bend the finger to squeeze the tool.
Gloves – Vibration, cold temperatures, glove type, or improperly fitting gloves all contribute to the stresses on the hands and increase the amount of force required to use tools and perform activities.
Tools can be designed to reduce the amount of force required to use them.
Lighting
Lights that are too dim or too bright can:
~ cause eyestrain, headaches, and related vision disorders, and
~ make employees perform their job functions more slowly.
Consider the effects of:
~ overhead and task lighting
~ glare
~ work surface layout
~ visual disorders and magnification, and
~ bad work habits.
Opening Boxes
Use safety knives or ergonomic razor-knives that require less wrist bending and have substantial handles that require less finger force for control.
Prevent Cumulative Trauma
~ Stretch arms, hands, legs, and back for 5 minutes each day before starting work.
~ Change positions frequently during the day.
~ Take short breaks and do hand exercises frequently.
~ Stretch arms, hands, legs and back for 5 minutes each day before starting work.
~ Change positions frequently during the day.
~ Use adjustable seating.
~ Use appropriate work surfaces.
~ Ensure appropriate workstation setup and placement of supplies.
~ Rest and take exercise breaks frequently.
~ Stand and stretch regularly.
Reaching
A number of tasks require employees to work with their hands above their head or shoulders, their arms extended full length, or their elbows raised out from their body. These kinds of tasks place stress on the shoulders, elbows, and back, and can result in an injury.
Elevated and extended reaches can also contribute to injury.
To reduce reaching hazards:
~ use ladders and lifts to reduce reaching
~ use bent-handled tools that allow straight wrists and elbows to be close to the body, and
~ place pallets and other materials on lifts or turntables to enable access to them from the proper height
or from the side.
Telephones
To reduce stress from constant telephone operation, use:
~ headsets
~ hands-free options
~ extended handsets
What is Ergonomics?
~ The study of people at work
* Ergo = work
* Nomics = the laws of operation or mechanics
* Ergonomics = the study of the mechanics of the body at work
~ Designing the job with the user in mind
* Consider the interaction of man, machine, and the environment.
~ The goal is to provide a comfortable, pain-free work environment.
What is Force?
Force is performing essentially the same motion or motion pattern over and over again with little variation in task assignment, sometimes with strain on the muscles from pushing or pulling.
Repetitive motion tasks often involve the use of only a few muscles, tendons, and body parts, which can become strained when the same motion is repeated frequently and often (every few seconds) or for prolonged periods (for several hours at a time, the entire work shift, or day after day) without adequate recovery time.
The severity of risk depends on how often the motions are repeated, the speed of the motions, the force required to perform the motions, and the number of muscles involved.
Work Station Setup (for office personnel)
