1. Computer Workstation - Ergonomics for Mouse Users
Andrew Drewczynski
Canadian Centre for Occupational Health
and Safety
This topic has been prompted by numerous questions addressed to the CCOHS’ Inquiry Service.
Many inquirers, not only from all over Canada but also from abroad, express concerns regarding the health hazards involved in using a computer mouse on a regular basis.
They ask for recommendations on how to eliminate the risk for injury that may result from overuse.
Suggestions and solutions are based mostly on CCOHS’ in-house experience and first-hand knowledge.

2. Common questions about using a computer mouse
What can I do to avoid discomfort and/or MS problems while using a computer keyboard along with the mouse?
What is the best position for the computer mouse?
Obviously, there is no one clearcut and precise answer to such generally formulated questions. Every inquirer represents a unique situation and requires a more or less unique solution.
Since there are not too many published solutions we think that sharing the solutions that we have developed, implemented, and evaluated can be of some value.
However, before I will present them I would like to show you the way we developed our solutions, because:
We are quite aware that our solutions and suggestions don’t exhaust all possible options, and
That each of you may benefit from our experience not only by duplicating these solutions (if they happen to suit your situation) but also by using a similar process to develop your own.

3. What is Ergonomics?
Ergonomics is the discipline that matches the job to the worker
and the product to the user.
A proper understanding of ergonomics is critical.
“Matches” is the key word. It means that ergonomics is a process, not a product.
The term “job” encompasses several components of equal importance.

4. Furniture: size & shape
The Job’s Components
Workstation
Furniture: size & shape
Layout
Equipment
Accessories
Tasks
Content
Variety
Sequence
Work-breaks
Rest-breaks
Worker
Skills
Work habits
Active input
Training
Awareness
The term “job” encompasses several components of equal importance.
Workstation: the workstation's physical shape and size, and the design of the tools and equipment to be used,
Job content: tasks -- their variety and sequence, work/rest-breaks
Worker: skills, work practices, work habits, worker’s active input
Each of these three components is “the most important”.
To achieve a “perfect”, or at the very least, acceptable match, all these components must be considered.
How does this translate to our very specific assignment – the computer mouse?

5. Workstation – One of the Job’s Most Important Components
No one can work safely and comfortably at a
sub-standard workstation

6. You and Your Workstation
fatigue
First things first – the quality of a computer workstation cannot be compromised.
Workstation design sets up the scene; if it is poorly designed, then there is no way anyone can work comfortably at it, with or without a mouse.
Due to time constraints my presentation is not about the computer workstation in general, but only on the specifics of mouse use.
Nevertheless, focusing on mouse use we cannot ignore the importance of the overall design of a computer workstation because the mouse is an integral component of it.
Mouse
What is so peculiar about the computer mouse?
Why are there so many complaints?
Is the computer mouse really such a bad guy?
Is a mouse worse than a keyboard?
Keyboard - mouse is an explosive duo – why so?

7. Standard Layout Let’s see what the problem with mouse is.
Here is a standard layout, with the mouse to one side of the keyboard.

8. Mouse – What it Does
Look what happens when we add an operator to the picture.
In order to operate the mouse while typing, the operator is frequently forced to reach forward or sideways, or even both at the same time.

9. Mouse – Common complaints
The main complaint is pain in the neck and shoulder region.
This is due to reaching forwards and particularly sideways.
Repetitive movements due to frequent clicking, however hazardous, are not primarily to blame; rather it is the effort of holding one's arm with little or no support, often in an unnatural position, for a long time.
Therefore our focus must be on eliminating or at least reducing over-reaching

10. Mouse Platform Out of these concerns the mouse platform was born.
It seemed that the numerical pad on the right side of the keyboard was rarely used.
By covering it with the platform we shaved almost 4” from the length of the keyboard.
The height of the platform elevated over the keyboard was an unwanted side effect. We tried to compensate for this by providing an optional forearm support.
Advantages :
Reduces sideways and forward movements
Reduces the overall area of mouse operation
Disadvantages:
The mouse is located slightly higher then the keyboard – this defect can be alleviated by using a slightly higher arm support. This solution or suggestion works and is still working quite well for some people.

11. Mouse Platform
Notice that reaching forwards and sideways is substantially reduced.

12. Keyboard with a Touch Pad
Here is a keyboard with a touch pad for applications that don’t require frequent and precise placement of the cursor.

13. Keyboard with a Touch Pad
You can see that the main goal – reducing the need to reach sideways and forwards – is achieved.

14. Short Keyboard
A narrower keyboard (14”) allows one to operate the mouse without movements sideways.
A cordless mouse further minimizes discomfort, as one is not fighting a tangled cord all the time.
The minor disadvantage of having to adjust to a slightly different key arrangement is well counterbalanced by substantially increased comfort.

15. Where Else Can You Keep the Mouse?
Placing the mouse between the operator and the keyboard requires using a cordless mouse.
However, individuals with shorter arms and those who cannot get close to the desk may not benefit from such an arrangement.

16. Where Else Can You Keep the Mouse?
The same arrangement with a minor variation – no mouse-pad

17. Proof-Reading
Here's a solution for proof-reading thick and heavy documents.

18. Task Design – Another of the Most Important Job’s Components
Even the “best” workstation does not guarantee comfort and safety if tasks are poorly designed

19. The Job’s Components Workstation Size Shape Accessories Equipment
Layout
Tasks
Content
Variety
Sequence
Work/rest-breaks
Training
Worker
Skills
Work habits
Active input
Awareness
The term “job” encompasses several components of equal importance.
Workstation: the workstation's physical shape and size, and the design of the tools and equipment to be used,
Job content: tasks -- their variety and sequence, work/rest-breaks
Worker: skills, work practices, work habits, worker’s active input
Each of these three components is “the most important”.
To achieve a “perfect”, or at the very least, acceptable match, all these components must be considered.
How does this translate to our very specific assignment – the computer mouse?

20. Work/Rest- Breaks Standard breaks Computer work
Scheduled vs. Spontaneous Work-Breaks
5 – 10 min every hour – a must
Micro-breaks? Mini-breaks?
What are those breaks for?
(muscular tension must drop to 0)
Working in a hurry

21. Reduce Mouse Use Function Keys vs. Mouse
Separate Typing from “Mousing”

22. We recommend that you separate typing tasks and mousing tasks.
The use of function keys is very much recommended.

24. Worker – The Component of Utmost Importance
Workstation
Size
Shape
Accessories
Equipment
Layout
Tasks
Content
Variety
Sequence
Work/rest-breaks
Training
Worker
Skills
Work habits
Active input
Awareness
The quality of workstation design and proper job design create only an opportunity to work safely and comfortably.
Taking or not taking advantage of such an opportunity is up to the individual worker.
Regardless of:
quality of the workstation design
quality of the job design,
A worker can still get injured.
Every point on the list is important but “active input” seems to be a critical one because:
Matching the job to the worker can
never be satisfactorily done
without worker feedback.

25. Need more info? Visit: www.ccohs.ca www.ccohs.ca/oshanswers/
Call: (Client Services)
(Inquiries Service)
Mail: CCOHS – Inquiries Service
250 Main Street East
Hamilton ON L8N 1H6