Darrell Skinner MScPT, CAFCI, CMedAc
Every job or task has unique physical and cognitive demands.
Each person has unique physical attributes and abilities.
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One size does not fit all http://keithtower.files.wordpress.com
Anthropometrics Most consumer products are built for "average" people, within an average height and weight range, and who are not physically challenged
The purpose of ergonomics is to match the physical demands of the job or task to the unique characteristics of the individual to minimize the likelihood of injury, and improve productivity
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Office Ergonomics Computer work is the predominant physical job demand in the modern office
Office Ergonomics Most office occupations are considered sedentary in overall physical demands but have special challenges Postural strain, static exertion, repetitive use of the hands and wrists, contact stress, and eye strain are the most common risk factors in the office Ergonomic interventions are aimed at mitigating these risk factors
Awkward Postures
Awkward Postures Joints and muscles work their best in midrange neutral position Poor posture places more physical demand on muscles and minimizes blood flow Reconfigure work station to avoid extremes of bending, twisting or reaching
Common Awkward Postures Posture Bending Example Leaning forward to view screen Twisting Reading from copy while keying Reaching Long reach to mouse or phone
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Contact Stress Prolonged contact stress places pressure on nerves and blood vessels Common areas include: the front of the keyboard key overuse of wrist rest area around mouse edge of the chair ttp://i.ehow.com
Static Exertion Static exertion refers to the performance of a task in one position for an extended duration Static muscle contraction decreases blood flow to the muscles and increases metabolic waste products www.ergoweb.com
Visual Fatigue Eye strain can result in headaches, blurred vision, and muscle pain, and be related to other risk factors
Eye Strain Every 30 minutes or so, shift your focus from the computer screen and scan around other subjects in the room, such as a window, clock, desk, or door. This helps promote eye movement and lessens chances of eye irritation and headaches.
Repetitive Strain Same action over and over again without sufficient time to rest has a cumulative effect Hands and arms most often affected and is common in keying and data entry Repetitive Strain Injuries are related to the rate of repetition, the force required and duration, and individual susceptibility
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NIOSH Suggested Guidelines Shoulder: more than 2 ½rpm Upper arm/ forearm: more than 10 rpm Forearm/ wrist: more than 10 rpm Fingers: more than 200 rpm Kilbom Å [1994]. Repetitive work of the upper extremity; Part II: The scientific basis for the guide. Int J Ind Erg 14:59 86
Red Flag Symptoms Pain that is not eased by a change of position Pain that is not eased by a night s rest Frequently shifting positions due to discomfort Increased fatigue and irritability at work
Red Flag Symptoms Decreased productivity Sleep disturbances, waking due to pain Pain that interferes with daily functions as well as work activities
Ergonomic Interventions
Engineering Controls Designing or modifying the work station, work methods and/or tools to eliminate or minimize static and awkward posturing, repetitive motions and excessive force
Administrative Controls Changing or modifying the work environment such as providing rest breaks, limiting overtime, job rotation, change in production rates or staffing
Desk Height Usual height 28 30 inches Legs fit comfortably underneath Frequently used items no more than 15 in away Lesser used items can be further away www.pb.unimelb.edu.au
Should have adjustable back height, seat height, back tilt, and seat tilt Chair arms if present should not interfere with the workers ability to get close to the work Adjustments should be easily made from a seated position
Adjustable Chairs Back and buttocks should be supported Back of knees should not be in contact with the back of the chair Feet not tucked under chair due to decreased circulation Stretching legs increases stress in lower back Support for dangling feet
(derived from Staffel)
Keyboard About 4 inches below desk surface Positioned near the edge of the keyboard tray to avoid forward reaching Avoid use of legs to tilt keyboard Hands hover over keyboard Most important concept is to maintain a neutral position of wrist
Alternative Keyboards www.ehs.pdx.edu Split keyboards are a common ergonomic recommendation to avoid deviation of the wrist
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Use of Wrist Rests Use of wrist rests is somewhat controversial as encourages contact pressure Used during rest periods when you are not typing www.ehs.pdx.edu
Use of Mouse The mouse and keyboard should always be on the same level to avoid repetitive reaching
Alternative Mice
Monitors Consider font size and font type Use highest resolution possible Set refresh rate to 70 85 HZ to avoid flicker Bifocals can be problematic use a lower position and increase backward tilt Antiglare screen if necessary many new monitors have antiglare screens
Ambient Room Lighting 240 lux* for simple detail 320 lux for average detail 600 lux for fine detail *One lux is equal to one lumen per square meter Example 50 lux is an average living room
Adjustable Footrests Only used if necessary to support feet and relieve pressure on the back of the legs http://i.walmartimages.com
Document Holders If a lot of work is done from hard copy a document holder will help decrease neck muscle tension Should be at the same height and distance as the monitor www.safecomputingtips.com
If phone calls are frequent job demand a telephone headset can reduce the incidence of headaches caused by cradling the phone in the neck
Computer Software Software programs which require excessive repetitive input may increase the risk for MSK Disorders Evaluation of new software should include useability No extraneous need for input when navigating menus Can text be resized or colors changed to reduce glare Is Your Software Contributing to a Musculoskeletal Disorder, Fraser M and Darnell D, p6,7 Ergonomics Canada (2009)
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Laptops/ Tablets More difficult to have ideal ergonomics due to compact nature Arm and neck posture may be compromised Use plug in mouse rather than touch pad When using it for a long time it is better to plug laptop into regular screen and keyboard Can just use auxiliary keyboard and mouse
Prevention Strategies There are long term benefits to taking the time to set up your work station properly Use good positioning and postural awareness Take short frequent breaks to change posture, walk, or stretch Rotate tasks when possible Be aware of developing early symptoms
Office Ergonomic Checklist Brief survey to identify potential ergonomic risks
Micro breaks Frequent short breaks are preferable to longer breaks Timed breaks time rather than task driven Can be used to rest, change posture, or to do some exercise Stand up every half hour to walk around a bit. This will ensure the continuous blood circulation in your arms and legs
Microbreaks A study in 2001 concluded that micro breaks had a positive effect on reducing discomfort during computer work, particularly when breaks were taken at 20 minute intervals (p < 0.05) Also, micro breaks showed no evidence of a detrimental effect on worker productivity. McLean, L., M. Tingley, et al. (2001). "Computer terminal work and the benefit of microbreaks." Appl Ergon 32(3): 225 37.
Deskercises Microbreaks are an excellent time to change your posture and do some easy stretches
This back stretch is recommended by the American Physical Therapy Association and targets the muscles of the seat, low back and shoulders.
http://rura.org/extras/treadmill desk
Safety Culture Safety culture is a term that reflects "the attitudes, beliefs, perceptions and values that employees share in relation to safety and is ultimately expressed in behaviour of the organization COX, S. & COX, T. (1991) The structure of employee attitudes to safety a European example Work and Stress, 5, 93 106.
Safety Culture Awareness and management of ergonomic risk factors, promotion of physical activity, and injury prevention are important components of positive safety culture
Web Resources Okanagan College How to Make Your Computer Work Station Fit You WorkSafe BC Association of Canadian Ergonomists
Thank you for your time & Good Health