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1 University of Scranton PMA CompaniesUniversity of ScrantonErgonomics presented by Mary Ann BubkaNovember 4, 2013
2 What will be covered: Ergonomics What is Ergonomics? Why should we be concerned?Musculosketetal Disorders (MSDs).Ergonomic Risk Factors.What you can do to prevent injury?Today’s agenda:We will discuss some supporting information on the importance of ergonomics.We will discuss the common injuries called musculoskeletal disorders.We will discuss risk factors that increase your chances of devleoping MSDsWe will discuss posture and body mechanics and how arrange your work to maintain good posture.We will talk about ergonomics: Fitting the job to the yourself, and how to prevent problems, and make better posture easy to achieve.
3 What is Ergonomicsthe science of fitting jobs to people.Ergonomics uses knowledge of physical abilities, limitations & human characteristics that apply to job design.
4 Ergonomic Designconsiders the tasks, equipment & environment to provide efficient use of worker capabilities while ensuring that job demands do not exceed those capabilities
5 Proper ergonomics can Improve Efficiency Increase Production CapabilityReduce Workplace InjuriesLower Workers’ Comp CostsReduce Absenteeism
6 Muscular Skeletal Disorders MSDs are medical conditions that develop gradually over a period of timeMSDs do not typically result from a single instantaneous event.
7 Muscular Skeletal Disorders Musculoskeletal disorders (MSDs) are an injury or illness to soft body tissue such as:MusclesNervesTendonsLigamentsJointsCartilageSpinal DiscsMSD
8 Why do we focus on Ergonomics? To minimize employee pain andthe impact on the organization ofergonomic exposures.
9 Ergonomic related injuries May be called:CTDs - cumulative trauma disordersRSIs - repetitive stress injuriesORMSD – musculoskeletal disordersThey normally affect muscles, nerves, tendons,ligaments, joints.OSHA now calls these injuries “Musculo-Skeletal Disorders” or MSDs, previously they were called CTD’s (Cumulative Trauma Disorders), or RSI’s (Repetitive Strain Injuries). The name change reflects the fact that the injuries may not have been caused by cumulative trauma or high repetition, but rather, there is some type of injury or disorder to the Musculo-skeletal system.
10 Carpal Tunnel Syndrome Tendonitis Tennis Elbow Trigger Finger Common types of MSDsCarpal Tunnel SyndromeTendonitisTennis ElbowTrigger FingerStrains/SprainsCarpal Tunnel Syndrome is the most famous, but not the most common MSD. The Carpal tunnel is formed by the carpal bones on bottom, and a strap of ligament on top. This little tunnel is the size of a dime and has tendons, blood vessels, and the Median nerve all inside. It affects only about 10% of population and is more common in women. Women often have a smaller tunnel, and hormone changes can cause swelling and put pressure on the nerve. It usually affects the thumb and first two fingers.Tendon disorders; Common diagnosis - Tendonitis, Tenosynovitis, de Quervains, Epicondylitis (golfers and tennis elbow). Tendons are like cables that connect muscles to bones and turn muscle tension into movement. Over- use occurs with high exertion or if the tendon rubs on other tissues when there is an awkward posture. Tendonitis is common in the fingers, wrist, elbow, and shoulder. Tendonitis is most often caused by repetitive, minor impact on the affected area, or from a sudden more serious injury.Tennis elbow is a common term for a condition caused by overuse of arm and forearm musclesTrigger finger and thumb are painful conditions that cause the fingers or thumb to catch or lock in a bent positionMuscle disorders (most common MSDs); eg., Strains and sprains, muscle aches or pain such as tension, spasm, cramp, or more chronic muscle pain called myo-fascial pain. Often influenced by overexertion or insufficient rest.Nerve disorders ( less common MSDs); Carpal Tunnel, Ulnar Neuritis, Thoracic Outlet Syndrome. Nerve disorders typically involve nerve compression or irritation. This can be from other tissues squeezing the nerve, outside forces squeezing the nerve or internal pressure from swelling or fluid build up.
11 Limited Range of Motion Swelling Common SymptomsSorenessNumbnessTinglingWeaknessLimited Range of MotionSwelling
12 Identify the risk factors Controlling MSDsStep 1.Identify the risk factorsRisk factors are conditions or circumstances that increase the chances of developing a MSD.The likelihood of developing an injury is dependent on the frequency and duration of exposure to risk factors.Both occupational and personal risk factors can affect an individuals well being at home or work.
13 Ergonomic Risk Factors RepetitionForceAwkward PostureStatic PostureContact StressTemperature ExtremesVibrationPsycho SocialThese risk factors are very important whether you are at work or home, doing sports, or other hobbies. Any time you are in a situation that has one or more of these factors, your increase your risk for developing Musculo-skeletal.
14 RepetitionRisk FactorsOccurs when the same movements are performed frequently such as keying or clicking a mouse.Can result in injury when the tissues are overused and do not have time to recuperate.Repetition can cause wear on tissues. We don’t know how much is too much. Some jobs require 75,000 keystrokes or more each day. With this much repetition the tendons in the wrist can travel back and forth as much as 100 yards per day.
15 ForceRisk FactorsForce is the amount of physical effort required by a person to do a task.With excessive force the muscles are working much harder than normal, this can lead to strain on the muscles, tendons, and joints..Forceful exertions can directly strain the tissues, and can cause the muscle to fatigue and build up waste products thereby causing discomfort. Reaching and lifting is 7 to 10x’s harder than lifting an object near to the side. Overexertion is one of the leading causes of injury in the workplace.A pinch grip produces 3-5 times more force on the tendons in the wrist than a grip with the whole hand.Demonstrate pinch grip vs. power grip
16 Force & ExertionForceful exertions place higher loads on the muscles, tendons, ligaments, and jointsFactorsWeightBulkinessSpeed
17 Is a deviation from the “neutral” body position. Risk FactorsAwkward PostureIs a deviation from the “neutral” body position.A “neutral” body position is safest and most efficient position in which to work.Awkward posture puts stress on muscles, tendons and joints.Awkward postures increase the tension and strain in the muscles, tendons and joints. The increased tension has a direct effect on the tendon, and also has the effect of restricting the blood flow to the affected tissues. This reduced blood flow causes waste products to build in the muscle causing increased discomfort.Lighting problems can induce awkward postures. Glare can cause the user to tilt the head to the side or lean, and poor lighting or print quality can cause the user to lean forward and bend the neck to read the text.Physically demonstrate this - have everyone try these activities.You can illustrate the effect of and awkward posture by having the class participants stand and then bend the knees slightly (about 6”) and hold that position. This bent (awkward) posture causes higher muscle tension, fatigue and discomfort in the legs.Holding this posture will illustrates the next concept - static postures.
18 The muscles become fatigued. Risk FactorsStatic PostureStatic posture occurs when one position is held for a prolonged period of time.The muscles become fatigued.This fatigue can lead to discomfort and even injury.Static postures: When muscles are held in a fixed position, the demand for blood and nutrients is high while blood flow is low. Waste products build up in the tissue and can cause muscle pain and discomfort.Static postures are worse if also awkward -this causes more strain. For example reaching the arms out straight increases neck and shoulder strain by 7 to 10 times. Sitting and bending forward causes about 200 to 250lbs of tension in the low back versus approximately 125 lbs of tension when sitting upright.Illustrate this by having volunteers hold light objects like a book or purse out at arms length away. See how long they can hold the arms away from the body.
19 Risk FactorsContact StressContact stress is caused by any sharp or hard object putting localized pressure on a part of the body.Contact stress will irritate local tissues and interfere with circulation and nerve function.Direct pressure can irritate tissues. This is common with direct pressure on the wrist (carpal tunnel), or forearm where the Ulnar nerve can get compressed. The Ulnar nerve (funny bone) can also get irritated from direct pressure of the arm rest (on a chair or in a car) on the elbow. The picture of the hands on the mouse illustrates direct pressure on the carpal tunnel area.
20 Extreme heat or cold may place stress on tissues. Risk FactorsTemperature ExtremesExtreme heat or cold may place stress on tissues.Extreme cold constricts blood vessels and reduces sensitivity and coordination of body parts.Excessive heat can result in increased fatigue and heat stress.
21 Heat & ColdHeat effects blood circulation & causes cramps, burns/rashes and general discomfort.Cold effects the body's blood circulation, causes hypothermia, loss of flexibility, distraction and poor dexterity.Comfortable temperature range68 to 74 degreesHumidity 20 – 60%
22 Vibration places stress on the tissues of the fingers, hand and arms. Risk FactorsVibrationVibration is typically not found in an office environment but can occur when using tools.Vibration places stress on the tissues of the fingers, hand and arms.Whole body vibration from driving puts stress on the spinal tissues.
23 VibrationExcessive vibration causes pain to muscles, joints and internal organsSoft tissue trauma to the hands, arms, feet and legs.
24 Risk FactorsPsycho-social IssuesStress, boredom, job dissatisfaction and anxiety can contribute to the possibility of developing a MSD.Psycho-social issues can create increased muscle tension and reduce a person’s awareness of work technique.
25 Other contributory factors SmokingDiabetesObesityAgeGenderLifestylePhysical activity level
26 MSDs are caused by Bending Climbing Crawling Reaching Twisting OverexertionRepetitive Exposure
27 Environment Risk Factors Heat or coldLightingVibrationTool designNoise
31 PostureProlonged standing - varicose veins, back stress, pooling of blood in legsSitting without back support - low back stressSeat too high - decreased circulation, (legs dangling over end) bruises
32 PostureShoulders rounded - Upper/lower back stress, respiratory distressLeaning forward - Lower back stressArms extended or over-reaching - Stress to arm muscles, upper back stress
33 PostureElbows "winged" - Joint stress at shoulder, poor use of bicep musclesStepping backwards - Loss of balance, displaced gravity, muscle stressLocking knees - Stress to back of knee, poor blood circulationBent Wrist – excessive force when gripping
34 RepetitionFrequent & prolonged repetition of the same movements cause muscle fatigue and stressFactors that increase repetition hazardsNumber of cycles per minuteForce requiredPosture
35 Gripping Factors that increase gripping hazards Bent wrist Surface areaSurface frictionVibrationType of grip
37 Hazard ControlsEngineering ControlsWork Practice Controls
38 Engineering Controls Re-design of work station Re-design of tools Lighting modificationVibration controlNoise ControlAutomationMechanical LiftingMaterial Flow
39 Work Practice Controls Work techniques & proceduresConditioning periodTraining Lifting techniquesPersonal Protective Equipment
40 Hazard Identification Reports of signs, symptoms & hazardsRecommendations from employees & supervisorsRecords review of existing safety & health recordsRoutine facility safety & health inspections
41 Information & Training Signs & symptomsImportance of early reportingSpecific hazards & controlsReporting MSDs & hazardsHow to recommend control methodsProtective MeasuresErgonomics program & their role
42 Employee Involvement Report of signs, symptoms & hazards Hazard control recommendationsAccess to information
43 Recordkeeping Reports of MSD or hazards Responses to employee reports Job hazard analysisHazard control recordsErgonomics program evaluationMSD management records
45 Controlling MSDs Step 2 – Fit the workstation to you. The workstation must be adjusted to promote a neutral position while a person works.When adjusting a workstation, keep in mind that all of the equipment interacts. Making one adjustment may alter another.
46 Knees and hips should be level. Adjusting Seat HeightKnees and hips should be level.Feet should be flat on the floor or footrest.Back of knees should not come in direct contact with the front of the seatpan.The chair should be adjusted low enough to keep the knees and hips at approximately the same level, and feet on the floor (or on a foot rest if the desk can’t be adjusted low enough).If the chair is too high there is extra pressure on the back of the thighs - this causes decreased blood flow to the legs, and can reduce the amount of support available from the back rest because the body is pulled forward slightly.If the chair is too low, there is extra pressure on the tailbone and the internal organs can get squeezed.Allow the user to choose the most comfortable height for themselves based on these guidelines. Some prefer to be higher, some lower..
47 Seat Back Support your low back using the chair’s backrest. The curve of the backrest should match the curve of your low back.The curve in the lower part of the back rest should match the curve in your low back. For most people the peak of the curve on the backrest should be above the buttocks and near the belt line. It may be useful to use a rolled towel or lumbar pad to support the low back.If the backrest is too low, you will not be able to slide your hips all the way back in your chair. If the backrest is too high, you will not be able to sit back in your chair comfortably.Demonstrate how to adjust seat back if applicable.
48 Adjust to lightly support arms. Arm RestsAdjust to lightly support arms.Use only for breaks or non keying/mousing activities.Lower arm rests slightly for typing or mousing.Arm rests can help support your upper body weight thereby reducing low back compression.It is recommended that they not be used while typing. Instead the arm rest should be down while typing and then raised when doing non typing tasks such as holding and reading documents etc.
49 Slight reclining gives the spine a rest. Variable Back StopSlight reclining gives the spine a rest.Keep the buttocks back, don’t slouch.Not all chairs have this featureLeaning back in the chair transfers the weight of the upper body onto the back rest and provides a good rest for the spine.HOWEVER - Leaning back and typing can cause the user to reach extra far for the keyboard and cause shoulder strain.We recommend rocking back in the chair as a “micro break” to be used when talking with co-workers, waiting for the computer to respond, or when just thinking. This lets the back muscles and spinal tissues rest and recuperate before the user sits up to type or bends forward to reach materials.We do want to encourage movement and postural changes and leaning back on occasion can be an effective way to accomplish this goal.Demonstrate how to adjust variable back stop.
50 Seat Tension Turn knob or adjust lever under the chair. Adjust tension to body weight.Soft enough to recline.Firm enough to support you.Not all chairs have this featureThe back tension knob works in conjunction with the variable back stop switch discussed on the previous slide. If the chair is set to recline the tension knob should be set to the users body weight.The tension needs to be low enough to allow leaning back, yet stiff enough to push the user back up to the keyboard and desk. For lighter individuals chair should have the back tension set low - perhaps as low as it will go.
52 Wrists should be in a neutral position. Keyboard should be flat. Key strokes should be light.The keyboard should be tilted or flat such that the wrist is relaxed, relatively straight and the fingers are curved. Straight or extended fingers require muscle tension in the forearm. Resting the wrists while typing causes the wrists to bend to the side and the fingers to stretch out and reach for the keys. This causes wrist strain.Keyboard short cuts (esc, page up/down, alt, etc.), the scroll feature on the mouse, and faster mouse speed can reduce the wrist movement required to maneuver through documents.It is better to move the whole arm as when playing the piano. Slide and move along the wrist rest, resting between strokes, and placing the hands down in different places as needed. Have the users imagine that the wrist rest is somewhat hot and they need to move around before they get burned.Light touch. Many users hit the keys with 4 to 5X’s more force than required. This causes unnecessary fatigue in very small finger muscles.Pace. Working at max speed causes high muscle tension. Backing off to 90% results in fewer errors, less tension, and perhaps as much or more work done.Breaks. Take micro breaks and vary the work to keep yourself refreshed and working at capacity.Most people can use a conventional keyboard for their entire career and have no problems. Some individuals, however, need to focus extra attention on keying techniques such as moving the arm around on the wrist rest as opposed to bending and twisting the wrist from one stationary position on the wrist rest.A smaller select group may need the special ergonomic keyboards that are split in the middle to reduce side bending of the wrist.
53 Adjustable Keyboard trays Make sure that your arms are in a relaxed position.Ensure adequate leg clearance under tray.A tilted keyboard may cause the fingers and wrist to bend back causing wrist or arm pain.A negative tilt (sloping down and away from the user) is often the easiest position for the wrist and carpal tunnel to work in. It wont work well, however, if the user needs to look at the keys to see where they are - this causes neck strain. To set a keyboard in negative tilt it will need to be slightly lower than the seated elbow height, and tilted down and away from the user.If the keyboard is elbow high it should be flat, if the keyboard is lower than the elbow it should tilt down and away, if the keyboard is higher than the elbow it should tilt up and away. The keyboard should be parallel to the forearm.
54 MouseMouse should be located adjacent to keyboard on same level.Hold hand lightly on the mouse.Use Scroll features.
55 MonitorsPlacement:directly in front of you at arm’s lengthtop of the screen is eye- level or lowerparallel to bright windowsAdjustments: height, angle contrast, brightness, color and refresh rate.If the monitor is off to the side the neck will be twisted.If the monitor is too close the eyes will be strained and the user will tend to lean back and end up typing with the arms extended (reaching out).If the monitor is too far away (or the font is too small) the user will lean forward to read the text. Leaning forward and bending the neck will also happen when viewing documents placed flat on the desk.If the monitor or active window is too high the eye lids will be open very wide resulting in an incomplete blink and dry eyes. Once the eyes dry the neck will tend to tip back because for near viewing such as computer work, the eyes want to look down 10 to 15 degrees. Also high viewing strains the visual system if the material is very close.Refresh rate is related to the “flicker” of the monitor. Refresh rates lower than 75Hz may contribute to headaches. Refresh rates are adjusted from the computer control panel-settings-advanced then select monitor. Srt refresh rates above 75hz.
56 Reach Zones Frequent Used Items Occasional Used Items Rarely Used ItemsFrequent reaching or heavy lifting should be done with the arms close to the body. Placing the frequently used tools close (keyboard, mouse, etc…) allows the upper arm and shoulder to hang comfortably near the side.Occasionally used item can be placed further back.Rarely used items should be high, low, of back out of the way.Users need to be especially careful to keep the mouse and other frequently used tools close by.
57 Supporting Equipment Wrist and mouse rests Copy/document holders called “RESTS” for a reason!Copy/document holdersHeadsetsFootrestsBack supportsIf you have samples you can show participants when and how to use each
58 What’s wrong with this picture? Monitors at different heights