Ergonomics

Monitors

Front- 20- 40 inches away Top line of screen is at or below eye level Perpendicular to the window Flat monitors take up less space Corner units provide increased depth

Risk Factors- Repeated and sustained exertions

Pace, exposure to how long

use a table

mechanical

Essential Task

"Described as the reason the job exists and the degree of expertise or skill that is necessary to perform the task."

Job analysis

"Purpose is to reduce risk for injuries, reducing/slowing the progression of an injury or reducing the disability resulting from an injury" "Provides an objective basis for hiring, evaluating, training, accommodating and supervising persons with disabilities."

Biomechanics

"laws of physics and engineering concepts to describe motion undergone by the various body segments and the forces acting on these body parts during normal daily activities"

Psychosocial demands

(job demands, pace, error rates, administrative support)

Neutral Body Position

-Comfortable working posture where joints are naturally aligned -This reduces stress and strain on the muscles, tendons, and skeletal system and reduces your risk of developing a musculoskeletal disorder (MSD).

Altering movement patterns and use of proper joint and body mechanics

-Distribute load over several joints (biggest muscles) -Use strongest, largest joints available for the task -Reduce force (slide verse lift)

office ergonomics

-Holistic -Client-centered (increases 's compliance!) -Worker size -Tasks/work demands -Worker habits

Evaluation includes

-Personal Characteristics- cognitive, psychosocial -Understand the components/demands of the job tasks -Assess each task for risk factors (within the activity or job) -Identify the Risk factors and the Interventions -Generate a report/Assessment

Role of OT In Ergonomics

-Provide services for individuals and populations in various settings -Design safe and efficient living environments, workplaces and products. -Influenced by legislation mandating safe, accessible workplaces.

Evaluation- Understand the components/demands of the job tasks

-Task analysis -Environmental Analysis -Physical Factors (light, noise, vibration, temp, safety) -Psychosocial (job demands, pace, error rates, administrative support)

Restructuring activities

-Work simplification -Altering the environment

Risk Factors

1. Repeated and sustained exertions 2. Forceful exertions 3. Awkward postures 4. Contact stress 5. Tool Design 6. Noise 7. Vibration 8. Illumination 9. Temperature

Seating

Adjustable back (conform to natural curvature of spine) seat height- feet rest on floor seat angle armrest height- allow shoulders to relax Seat depth

3 Categories of Ergonomic Interventions

Administrative Controls Engineering Controls Individual Controls

Personal Risk Factors:

Age, Gender, Hobbies, Previous Injuries, Physical or Medical Conditions, Pregnancy, Medications, Smoking and Fatigue

Task analysis

Assessment of the physical, cognitive and psychological demands of the job. Interaction between the worker "by a detailed description of the human task requirements." -within job analysis

CTD (cumulative trauma disorder) example

CTS, tennis elbow, DeQuervian's Syndrome

Administrative Controls

Changes in the nature of work: schedule, rotation, assignments of tasks

Duration:

Continuous exposure may not allow sufficient recovery time for muscles, tendons, and nerves.

Job description

Defines the essential functions of the job

ventilation

Diffuser Humidity between 30-60% Temperatures 68- 70 degrees F

Keyboards

Directly in front Shoulders relaxed and elbows close to body Wrists straight and in-line with forearms Consider placement height, distance, design and use

Risk Factors- Vibration

Duration of exposure

Task analysis includes all of the demands, such as...

Employer and employee interviews Observation of multiple employees doing the job Measurements of forces Frequencies and duration Postural requirements Environmental Psychosocial conditions W&S pg 684

Engineering Controls

Equipment and workplace designs or changes that reduce human effort

job description includes

Essential job tasks Physical and mental demands/requirements Equipment/tools necessary Work space Environmental Conditions

OT uses ergonomics by

Evaluation, Intervention, Tool and Environmental Design and Modifications

force

Forceful exertions due to weight, friction, or posture can stress tissues (ex; muscles, tendons, ligaments) beyond their capacity, lead to fatigue and possible damage ex- mechanical- using garbage lifter

Risk Factors- Temperature

Hot/ Cold

Musculoskeletal Injuries

Injuries & disorders (MSD) of the muscles, nerves, tendons, ligaments, joints, cartilage, and spinal disc.

CTD (cumulative trauma disorder)

Injuries that occur over a period of time due to repeated trauma or exposure to a specific body part such as the back, hand, wrist and forearm. Muscle joints are stressed, tendons inflamed, nerves pinched or flow of blood restricted. -ergonomics looks at strain and identify these errors

awkward posture

Maintaining good posture such as straight wrists, elbows close to body, straight head is often difficult due to misalignment between the user and computer station/ job leading to awkward postures.

Evaluation- Personal Characteristics- cognitive, psychosocial

Medical History Physical Activity Level Strength Endurance

Enviornment

Minimize Glare from windows and lights Maintain good air circulation Avoid sitting directly under air conditioning vents

ex of repitition

Mouse limited movements to just a few fingers. Poorly designed stations require repeated reach to use the mouse/answer phone. Can fatigue shoulders and irritate tendons.

Why are MSD the Signs and Symptoms of MSDs important?

Once your employees are aware of ergonomics and risk they need to be able to identify signs and symptoms which are precursors to WMSDs. Early reporting can allow us to identify risk in the workplace and correct it before an employee is injured. Not all pain and discomfort may lead to injury- for example a physically demanding inventory task which only occurs annually. The worker has time to recover after inventory is complete, but the pain may indicate an opportunity for ergonomic improvements. But Pain and Discomfort are usually precursors to injury and should be considered warning signs or an indicator of a need for improvement.

What are MSD Signs and Symptoms?

Painful aching joints, muscles Pain, tingling or numbness Fingers or toes turning white Shooting or stabbing pains (nervous system) Swelling or inflammation Stiffness or difficulty moving Burning sensation Pain during the night

repitition

Perform the same motions repeatedly at a fast pace and with little variation. Users are at a computer for unlimited amount of time in the same position. Lead to tendon and tendon sheath injuries

Individual Controls

Physical, cognitive, and social skills and performance of workers.

Reduce repitition

Properly arranging workstation and components. Mouse close to keyboard Maintain good posture/neutral position Rest periods- micro breaks 5 min of each hour Task rotation

Goal of ergonomics:

Reduce occupational injury Reduce workers compensation costs Improve work quality Reduce absenteeism (training cost, lost income) Compliance with government regulations

Controlling Risk Factors

Safe, efficient job design is dependent upon coordination of all aspects of the system

Forearm and wrist anatomy made simple

The forearm can easily be compared to a turkey led prior to baking The meat is the muscle. If cut before cooked, it bleeds. Therefore, muscle has a good blood supply and heals quickly Each segment of meat or muscle is packaged by a thing, clear, slimy coating. This is the fascia. It helps muscles to glide against neighboring muscles Each muscle group has a long, hard, white stick on the inner end of the turkey leg. This is the tendon. If cut before or after cooking; it does not bleed. Therefore a tendon does not have its own blood supply and takes a long time to heal. The tendon in the forearm/wrist has a protective and lubrication coating called the synovial sheath Irritation / compression to the sheath causes inflammation - this is know as tenos_ The thigh white tissue that you have to cut when separating the turkey leg from the body ligament. Ligament is made of the same connective tissue as tendon, it just has a different function The point Muscle has a good blood supply and heals quickly Tendon and ligament do not have their own blood supply - therefore healing make take several months provided further irritation is not experienced

Ergonomics

The study of how to fit work to the worker

Risk Factors- Forceful exertions

What part of the body, amount of force, frequency, ect. (bursts)

People say that a hard days work never killed any one? It is good for you?

While a hard days work may not kill you it can cripple you. Fatigue at the end of the day is not necessary to show you worked hard- Work Smarter Not Harder!

Knees

are about the same height as the hips with the feet slightly forward.

Shoulders

are relaxed and upper arms hang normally at the side of the body.

Thighs and hips

are supported by a well-padded seat and generally parallel to the floor.

Pushing or pulling with more than 20 pounds of initial force is also classified

as forceful lifting.

The Navy Ergonomics Program is currently looking into a measurement of vibration levels on Hovercraft because the craftmasters are complaining of

back pain.

if things were moved- engineering, if space already available- individual

back up and sit on the wall

Essential task is ____________ accomplished with or without accommodation

basic job duties

neutral postures promotes

blood flow and gives us our greatest mechanical advantage but even a neutral posture can not be maintained all day.

Monitor Keyboard Seating Desk Documents Mouse Lighting

different ways to adjust ergonomics

individual control

dont lift with your back

Using ergonomic approaches by __________ and __________

equipment assistive technology

You can experience contact stress to your forearms when you rest them on the leading edges of work tables or, if the nerves in the forearm are affected, your fingers and hands may tingle and feel numb, similar to the feeling when you hit your "funny bone".

external

You may experience pain and numbness in your legs if blood circulation is cut off by contact with the leading edge of a chair.

external

Lifting more then 25 lbs.

from below the knees, above the shoulders, or at arm's length

Compression

from grasping or contacting sharp edges, can concentrate force on small areas, reduce blood flow and nerve transmission and damage tendons

Force is manifested

from strong muscle contractions (demonstrate a bicep curl) my muscle is creating internal force.

Feet are

fully supported by the floor or a footrest may be used if the desk height is not adjustable.

avoid twisting

individual

bending cart use another person

individual mechanical administrative

"The scientific discipline concerned with the understanding of_____________________ and ____________, and the profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance".

interactions among humans other elements of a system

Tendons can be damaged when repetitive finger motion tasks are performed with a bent wrist.

internal

Contact stress

internal external

Compression or Contact Stress

is a Concentrated force on a small surface area that reduces blood flow. One of the most common sources is when you have a sharp, hard desk edge creating a compressive force on the forearm. The forearm is a delicate area with nerves running close to the skin, compression of the forearm impedes nerve conduction. It is best to pad the edge of the work surface (as shown in the example) or to set the work surface to the correct height so the user doesn't need to rest his/her arms.

back

is fully supported with appropriate lumbar support when sitting vertical or leaning back slightly.

Motions that are

isolated and repeated for prolonged periods can cause injury

"Fit the _____ to the PERSON"

job

Head is

level, or bent slightly forward, forward facing, and balanced. level, or bent slightly forward, forward facing, and balanced. Generally it is in-line with the torso.

Duration __________ with other risk factors

magnifies

Or force is

manifested as a strong physical exertion such as picking up a heavy load.

avoid carrying heavy load by cart

mechanical

use a right tool to manipulate force

mechanical

use vertical handles to accommodate different height

mechanical

Internal stress

occurs when a tendon, nerve, or blood vessel is stretched or bent around a bone or tendon. -wrist flexion causes stress on body in tendons -awkward posture

Lifting more then 75 lbs.

one time

Static postures,

or positions that a worker must hold for long periods of time, can restrict blood flow and damage muscles

Ergonomic Approaches by activity....

pacing, planning, prioritizing and problem solving to modify activities and routines. Balance activity w/ rest. Trombly pg 1224 and 1227

want to be _________ light

perdpendicular

Strength varies by person and as individuals we differ in tolerance and ability. The strength to lift, physical endurance to say row a boat, strength to maintain a static posture are_____________. Both of your instructors are about the same size but one of us weight trains and can lift a great deal more.

personal attributes

Nomos

principles or natural laws

Musculoskeletal Injuries examples

rotator cuff tendonitis & tension neck syndrome

Holding a posture for extended periods of time is known as as

static posture.

Elbows

stay in close to the body and are bent between 90 and 120 degrees.

Hands, wrists, and forearms are Shoulders are relaxed and upper arms hang normally at the side of the body.

straight, in-line and roughly parallel to the floor.

External contact

stress occurs when part of your body rubs against a component of the workstation, such as the chair seat pan or edge of the desk. Nerves may be irritated or blood vessels constricted as a result. -resting hand on computer when typing compressing wrist

Users are at a computer for unlimited amount of time in the same position lead to

tendon and tendon sheath injuries

Force guidline comes from

the OPNAVINST app A checklist regarding heavy lifting.

Static postures prevent

the flow of blood which brings nutrients to the muscles and carries away waste products. Holding a muscle in contraction causes waste products to build up and leads to fatigue. Also, our heart is a strong pump which pushes clean blood through out our body. Our veins don't have the pump, they need circulation or movement to bring the wasted blood back to the heart. Static postures prevent the blood flow with an end result of waste accumulation which changes the PH in our muscles resulting in a feeling of soreness or muscle fatigue.

Excessive muscle tension / contraction may cause

the muscles to contract to their max which results the muscle fatiguing or tiring out faster - Repeated trauma of this type to muscles can cause damage

Whole exposure results from

vehicles such as air craft and bus drivers- the main effect is usually to the lower back but studies show high exposure can reduce circulation and cause disorientation and motion sickness. Whole body vibration is extremely hard to measure.

Ergon

work

Change Positions Frequently because

working in the same posture or sitting still for prolonged periods is not healthy. -Make small adjustments to your chair or backrest. -Stretch your fingers, hands, arms, and torso. -Stand up and walk around for a few minutes periodically.