Office and Computer Workstation Ergonomics Margaret Cook PhD Occupational Health and Safety Science Programs
Today s presentation What is the ideal workstation: Equipment: Seating/Chairs Sit/Stand/Active workstations Work layout Task design Challenges for the future
WHAT DOES THE IDEAL WORKSTATION LOOK LIKE?
Seat depth Traditional approach: should not exceed the buttockpopliteal length of the smallest user ideally should provide clearance of 50mm between seat edge and the back of the lower leg New designs: Seat slide mechanisms waterfall and/or flexible fronts
ZUO Criss Cross Black Office Chair http://www.homedepot.com/p/zuo-criss-cross-black- Office-Chair-205030/203030983 Herman Miller Mirra 2 http://www.hermanmiller.com/products/seating/ performance-work-chairs/mirra-2-chairs/experiencemirra-2.html
Seat Angle Aiming for an open angle between the trunk and the thighs, this makes it easier to maintain lumbar lordosis [Gadge & Innes 2007, McGill & Fenwick 2009] kneeling chairs: open angle but no lumbar support forward tilt of seat pan Use of backrest incline
Effects of different sizes of lumbar support and of increasing seat angles on disc pressure, based on Andersson et al 1974. [Grandjean, 1988]
increased trunk motion in sitting which is facilitated by the use of specific chairs or equipment [O Sullivan et al 2012] DYNAMIC SITTING
Arm rests If they are good they are great: Height adjustable Preferably adjustable in other dimensions as well Old fashion armrests that limit access under the work surface have to go
Say NO to the ball as a chair WHS Regulators have essentially banned fit balls being used as office furniture in workplaces Why? No height adjustability Don t accommodate twisting actions Tend to roll away Fatiguing for long periods of time
Deciding not to sit Standing workstations Sit-Stand workstations High Desk with perching stools Active workstations
Why would we stand? Decrease in musculoskeletal complaints [Husemann et al 2009; Karakolis et al 2014] Enhances cognitive performance activates the cardiovascular system and leads to increased stimulation and awareness [Watanabe et al 2007] But poor compliance in the longterm [Wilks et al 2006]
Another argument for not sitting lifestyle disease Evidence suggests that reducing sitting could have a considerable impact on cardiovascular disease and type 2 diabetes [Healy et al 2011]
How long to stand 1/4 to 1/3 of the desk bound time should be standing [Husemann et al 2009] Ideally this will occur within a single hour BUT having the choice as to how often to change working position can itself affect musculoskeletal complaints [Argiropoulos & Seidel-Fabian, 2002]
Stand or Sit-Stand Workstations What works in the workplace? How do you encourage use? Cost normally makes it prohibitive for all workstations to incorporate a standing option How many standing workstations should be in a workplace? Will people hot desk into them during the day?
Straker [2009] The health burden associated with insufficient physical activity is likely to far exceed the health burden associated with computer-related musculoskeletal disorders (pp 832) BUT we need to be aware that all the current focus on avoiding sedentary posture is not considering musculoskeletal risks at all
HOW SHOULD WE RESPOND TO THIS? Create a culture of facilitating movement (providing a sit/stand desk may be only one small part): Periodically stand to work Standing meetings Walk to talk to people rather than email Move printers, and other shared equipment, to a more distant location Use of a participatory approach to develop these strategies has been shown to be effective [Parry 2013]
Desks Greatest support is for shaped desks with a single surface Where desks are rectangular they need to be a minimum of 900mm deep Height adjustability is a great asset, many desks are too low for tall workers
SETTING UP THE WORKSTATION
First Questions Does the worker have their own workspace? increasingly the answer will be no, particularly for inner city workers Does the worker have a PC or are they dependent on a laptop or tablet? again increasingly the answer will be no Both of these will impact on your recommendations
Screen Height Screen height is one of the most complex and controversial issues Dynamic interplay between the oculomotor system and the musculoskeletal system Two issues: Neck pain Visual comfort Neck comfort - anything that is comfortable, as long as there is no neck extension Visual comfort - go low
Where do you put the screen 2? The further away the better, particularly with high placed screens All to do with visual comfort Best: big screens, big visual image and far away Multiple screens placement needs to consider usage and visual comfort
Floating Traditional approach Works best with skilled touch typists Critical to keep the desk surface height low
Supporters Now recognised as the preferred forearm posture [Kiss et al 2012, Rempel et al 2006, Cook et al 2004] Can be achieved by using arm rests or by using the workstation surface Key is to support the proximal part of the forearm
Use of the workstation surface with forearm support Key elements: Input device at least 20cm from desk edge Use full forearm support (or at a very minimum 2/3 of the forearm) Natural position for non-touch typists Important to keep the seat height low
Workstation layout Arrange the materials and equipment based on the individual and the specific task demands: What tasks do they do? How long and how often? What equipment do they need? What do they need to see? How far can they comfortably reach? How much space do they have?
Traditional working zones Comcare Australia [1996]
Most important principle Avoid over-reaching on a prolonged or repetitive basis The relative position of the mouse is at least as important, if not more, than usage time [Kiss et al 2012]
Forearm support working layout
Mousing technique Use of non-dominant hand mousing, this can balance the work load between the two hands Adjust mouse settings to suit accuracy and style, including: mouse speed, acceleration and shadowing
Activity-based work environments Being driven by real estate costs and Green Star targets Key relevant features: No-one has their own workstation No fixed PCs everyone has a laptop or tablet Employees have to be managed by outputs Working at home is encouraged
Learnings Facilitate movement into work An open angle of the hip and thighs will reduce LB discomfort Forearm support (particularly proximally) should be promoted Mouse use is more concerning than keyboard use and its position is critical
Challenges as we go forward Addressing prolonged sitting based on overall health concerns Activity-based working the new hot-desking Rapidly advancing technology touch screens, tablets
Resources
Thank you for listening Dr Margaret Cook Program Advisor OHS Science m.cook4@uq.edu.au