Ergonomics

Office Ergonomics


Many of today’s workplaces are recipes for musculoskeletal and repetitive strain disasters. Thankfully, it’s all preventable. Avoid personal injury with the following information on ergonomics in the office. The human- centred focus of ergonomics can help improve safety, efficiency and overall quality of life. Here are three diagrams we think you may find useful.

 

Ergonomics Diagram Office Ergonics Diagram
Summary

•    Feet flat on the floor or on a foot rest, with ankles in front of the knees
•    Joints (hips, knees, elbows and ankles) open slightly (90° to 120°)
•    Thighs horizontal to the floor
•    Head aligned with the spine (ears, shoulders and hips are all in a straight line)
•    Elbows at an angle between 90° and 120°
•    Forearms supported and kept between horizontal and 20° up
•    Wrists straight and aligned with the forearms
•    Working object (papers, computer monitor, etc.) positioned so that it is 10° to 30° below the line of vision
•    Stand up and move around whenever possible
Mousing Ergonomics

 

Posture Diagram
Posture
There is no singular body position that is recommended for sitting. This is because prolonged sitting (or any kind of sedentary, fixed position) is not recommended at all. Sitting may be relaxing for the legs, but it actually increases the pressure on the spinal discs. Unfortunately, sitting down for long periods of time also leads to compression of tissues, especially in the spinal column, muscle fatigue, reduction in metabolism, reduced blood circulation and accumulation of extra-cellular fluid in the lower legs. Even a perfectly straight and upright posture shouldn’t be held continuously. The human body is meant to move, not to stay still. Variation is good. In fact, slouching is not always bad for you; slouching is the body’s natural way to alleviate the strain and tension of the overtaxed muscles that are working to maintain your posture. Occasional forward slumping can help provide muscle relief, as can reclining and pressing into the back of your chair. However, if the shoulders are hunched regularly, or if the arms and back are unsupported, it can cause neck, shoulder and upper back pain.

Here are a few specific posture corrections to keep in mind:  Firstly, your feet should be flat on the floor. If your feet don’t reach the floor, you should get a wide, flat foot rest so that your feet and thighs can all be horizontal, instead of angled. Ideally, your feet should be flat on the floor, your shoulders should be relaxed and slightly back, your pelvis should be rotated slightly forward, your upper arms should hang down, your forearms should stay horizontal and your wrists should be straight. If you have a desk job, try to change your body position frequently to get some motion and variation into your day. Get up and walk around whenever possible. You will feel more physically comfortable and more mentally alert.

 

Furniture
If possible, your office workstation should fit your body size and your preferred working habits. If you do not have control over choosing your desk and chair at work, at least make sure that the furniture in your home office is carefully selected.

Desk
Hopefully your desk is comfortable, adjustable and task-oriented. Ideally, it should be suitable for both sitting and standing. Make sure your desk isn’t too high and forcing your shoulders up too far. Remember, when you are seated, your shoulders back and down, not hunched up creating unnecessary muscle tension. It’s best to place all of the things you must operate with your hands within easy reach at elbow height and directly in front of you on your desk. Your area of range when seated should be near your torso, about 10 to 40 centimetres in front of your body. That way, you won’t have to twist or contort awkwardly.

Chair
There is no such thing as a “one size fits all” ergonomic chair. The right chair for you depends on your individual body proportions. That being said, you definitely want a chair with good support. Sitting keeps the upper body stable and requires less muscular effort than standing, but only when the seat is supportive enough for the body to be comfortable. A hard chair seat can generate pressure points, which you do not want. 
If you find it comfortable, a downward sloping seat is a good idea as well since it minimises the backwards tilt of your pelvis. A chair with wide, padded arm rests is best, as arm support reduces spinal stress. As for the backrest of your chair, it should be large enough to provide support from your neck down. The back support carries some of the weight of the upper body, reducing the load that the spinal column must transfer to the seat. Plus, leaning against a backrest is relaxing. It’s also preferable for the angle of your backrest to be adjustable, allowing you to change postures and recline when you need a break. The least stressful sitting posture is when your back can lean into a rearward-reclined backrest.

Computer
Since most of the time you spend at your desk is likely on your computer its setup is very important. Firstly, the computer monitor should be placed directly behind the keyboard, not high above or off to the side; you don’t want to crane your neck or have to look up to see the display. Your monitor should be at a convenient distance and height from your eyes (about half a metre/ slightly less than arm’s length) so that you can look down to see the screen without any eye strain.

Meanwhile, your computer keyboard should be placed directly in front of your body, over top of your thighs and at about elbow height when your shoulders are relaxed. A keyboard located too high requires unnecessary muscle tension in the raised shoulders, arms and spread elbows. As for choosing a keyboard, split keyboards have their advantages, but are much pricier than the standard variety. If nothing else, a flat keyboard is better than an angled one, so don’t prop your keyboard up on its kickstand.
Bent-wrist keyboarding is another problem to look out for as it can lead to carpal tunnel syndrome (a repetitive strain injury that interferes with the use of the hand). Carpal tunnel syndrome is caused when pressure is put on the median nerve where it runs through the carpal tunnel (an anatomical tunnel between the wrist bones and flexor retinaculum).  Foam pads are recommended as they raise wrists levels with the surface of the keyboard so that typing can be done with straight wrists. A foam pad can provide comfort and support to the heel of the hand so that the wrists don’t press into sharp desk or table edges.

You also want your mouse to be close by so that you don’t have to reach far out in front to operate it. The best case scenario is when your keyboard and mouse are at the same level. If one is higher than the other, one sided muscle tension in your back, neck and shoulders is likely to occur. When both mouse and keyboard are on par, your arms and shoulders can be at equal 90 degree angles. Heavy mouse use is often associated with wrist pain, so be careful.

Forarm and Wrist Stretches
Use one hand to spread apart and straighten the fingers of the other hand and then stretch your wrist back gently as far as you can. Keep your elbow straight. Relax your hands.
 
You should feel a gentle stretch in the forarm flexors, then switch direction and stretch the forarm extensors.
 
Hold each stretch for at least 30 seconds to 1 minute. Can be done several times per day.
 

Forarm Stretches

Review
Maintaining any one body position over extended periods of time without change is onerous. Repetitive strain on your back, arms, wrists, and fingers can be caused by lack of whole body movement, unsuitable posture and repetitive overexertion in the workplace. Be conscious of your body positing, the setup of your workstation and the furniture and office equipment you select. Most importantly, take short breaks often throughout your work day. Brief but frequent interruptions to focused desk work will restore your ability to continue working efficiently. Taking a 5 minute break every half hour will help you to maintain both your productivity and your health.

Article Researched and Written By: Vanessa Day

Edited by Kasey Thompson, RMT


References:
http://www.ccohs.ca/oshanswers/ergonomics/sitting/sitting_position.html

Kroemer , Karl H.E. and Anne D. Kroemer. Office Ergonomics. New York, NY: Taylor and Francis Ltd., 2001. 

Peterson, Baird and Richard Patten. The Ergonomic PC. Toronto, ON: McGraw-Hill, 1995.
 

 
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