Articles in Category: Ergonomics

Workstation Ergonomics

Written by Don Williams BSc, MChiro, ICSSD. on Wednesday, 23 September 2015. Posted in Ergonomics

Workstation Ergonomics

By Don Williams

 

In this article we will introduce some of the basic essentials of posture and how to avoid creating problems when at work.

 

Historically, we developed as cultural groups who were required to do a variety of different tasks to survive. As a consequence our musculoskeletal system developed to cope with these tasks and really did very well.

However, in modern society, many people have very repetitive jobs or adapt one static position for the whole day, often not realising how long they sit in one position before moving. The classic is computer work. We see a range of common injuries that are directly related to static positions and postures.

 

There are essentially 2 reasons that people get issues with static positions at work, the first one is obvious, poor posture. The second issue is a little more insidious and relates to the way our muscles, ligaments and tendons are constructed.  When these structures are loaded for a longer period of time, which is unfortunately only 15-20 minutes, the elements go through phenomenon called visco-elastic creep, where the structures stretch out and are not maintaining their original state. When the pressure is release, you sit up straight again, it takes 2 minutes to recover half the pliability, however, it takes a further 4 hours before the structure fully returns to the pre-stretched state. What this means to office workers is, that if you sit down at 9 am and slouch for half an hour, it will be almost 1.30 before the body has recovered from this slouch. This effectively creates a degree of instability, or loss of control of the joints.

This phenomenon is partly the reason why people will often report that they, “weren’t doing anything, I just turned around and my back/neck went”.

 

A really simply solution to address this and start to improve your posture is to set a meeting reminder or alarm on your computer or smartphone which goes off every 15 minutes to remind you to get up and move. Using a “Microbreak Routine” can significantly reduce the neck and upper back stiffness often associated with seated postures and will in fact make you feel more awake and increase productivity!  When you fall into a slouching position it restricts breathing, which increases fatigue. The following are 2 simply exercise to try during your micro break.

 

General Stretch regime

During the “Micro-break”, try doing a very simply stretch routine. Stand up tall, rotate all the way to the left, then to the right, bend all the way to the left, then to the right (stretch the arms out overhead as you go), slowly reach down to touch the toes then slowly reach backwards arm high over the head, take 2 deep breaths then sit down again in good posture.

 

Brugger Position

Perch on edge of chair, spread and externally rotate legs (turn feet out), lift chest, tuck chin in, sit tall, look straight ahead, push the tip of tongue into the roof of the mouth, 1 finger width behind teeth, (rotate out) your arms & hands (so the thumb is pointing behind you) as you exhale actively, press toes down with inhalation and raise toes up with exhalation repeat 3-4 X.

 

Neutral Spine

When looking at posture, it is a great idea to analyse everything you do on a day to day basis and understand just how often you deviate from an optimal postural position.

When viewed from the side and standing comfortably, a “plumb” line should pass directly through the ears, shoulders and hips. When standing, this should also pass through the knee caps and ankles. Be careful not to roll the shoulders forward (elbows winging), poke the chin out or let the chest sink towards the floor. Don’t try to pull the shoulders back, instead focus on sitting or standing tall, as if you are trying to touch the ceiling with the top of your head, thumbs pointing forwards. GENTLY stare at the horizon and tuck the chin in.

 

This month, try integrating “Micro-breaks” into your work routine and try to use the neutral spine position when sitting or standing at work.

 

Brugger Position                               Neutral Spine -

 

 Brugger position 2                     Neutral Spine

 

Workstation Ergonomics Part 2

Written by Don Williams BSc, MChiro, ICSSD. on Wednesday, 23 September 2015. Posted in Ergonomics

Workstation Ergonomics Part 2

By Don Williams

 

 

When setting up the seated work station correct chair and desk choice is critical

When selecting a chair and desk, there are a number of essential features which should be addressed.

 

Chair selection

  • Seat base - stable 5 star base which swivels and is on wheels or castors (most modern chairs will have this).

  • Seat pan - height adjustable with a range suited to the desk. Optimally, the seat pan should be tilt adjustable.

  • Back rest - should be stable and independently adjustable for height and angle

  • Lumbar support - integrated into the backrest. Should be adjustable so that it sits in the small of your back.

  • Armrests - not recommended as they are likely to interfere with the ability to move the chair close enough to the desk. Some chairs will have armrests which drop down to leg height. These are uncommon and expensive.

  • (Diagram located on the bottom right of this page.)

 Chair Selection

 

Chair adjustment

 

Chair adjustment 1 

The goal of the chair adjustment and height is to have you sitting comfortably in front of your desk with the shoulders and elbows relaxed, not to much pressure on the backs of the legs, looking straight ahead at the screen. To get a good rough chair height, stand in front and facing chair, adjust the height so that the front of the seat  pan is just below your knee.

 

Chair adjustment 2 

Next, sit on the chair and keep your feet flat on the floor. The hips should be slightly higher than the knees.

Push your hips as far back as they can go in the chair Grasp the back of your legs between the seat-pan and the back of your knee. Wiggle back or forward until you can just fit your hand comfortably between the seat - pan and the back of your knee.

 

THE BACKREST IS THERE TO SUPPORT YOUR BACK, MAKE SURE YOU USE IT!

Adjust the backrest so that the lumbar support fits into the small of your back. The centre of the lumbar lordosis must be supported to ensure good posture and alignment of the neck and shoulder. Lean against the backrest until your back is at least 90° reclined angle to your legs, although a slightly more open posture is better, up to 110° maximum. If your armrests are in the way, remove them. Tilting the seat-pan a fraction downward helps give your body a slightly more open posture and relieves any pressure you might have under your legs.The end result should see a straight line through the ears, shoulders and hips, with little pressure on the neck and shoulders.

 

Desk selection

Height adjustable desks are the preferred option. Height to the top of the work surface should be between 580mm and 730 mm above floor level.

  • For a fixed height desk, between 680mm and 720mm.

  • Minimum work surface area - 1500mm X 900mm with maximum bench thickness of 25mm.

  • The leg space should be 800mm wide X 550mm deep X 580mm high minimum.

  • No sharp edges, rough surfaces or protrusions.

  • Desk surface should be continuous, mouse and keyboard at the same level for effective use.

The viewing distance to work and monitor should be between 350mm and 780 mm. As a rough guide, with monitors, when viewing videos/movies a comfortable range is that the viewing distance should be approximately twice the dimension of a screen, so a 23 inch monitor should be around 46 inches away, however, with focused work, the effective distance is usually around 150% (so in the example of a 23 inch monitor, the eyes/face should be somewhere around 35 inches from the screen).

 

How to Sit at Your Desk

It is important to remember that the majority of the time, you should be looking and working straight in front of your body and head, looking directly at your monitor, rather than having it off to the side, causing you to turn your head all day. It is best to have soft light behind the monitor and no hard lights shining directly on the screen.

 

Approach your desk and place the keyboard directly in front of you, but give yourself enough space between the keyboard and the edge of the desk so that you can rest the pad of your thumb lightly on the desk for a moment when you are not typing. Never rest your wrist on the on the desk. ( The mouse should be to the side of the keyboard, rather than out in front which will cause you to stretch and reach out, this commonly causes slouching posture as the day progresses).

 

Keeping your wrists straight, observe the angle of your forearm. If it is parallel to the floor, or slightly more open, up to a 100° angle at the elbow joint, then move on to Step 4. If not, then proceed to 3b.

 

Chin slightly tucked in and looking straight at the middle to top of the screen (as if nodding yes).Try to ensure that the ears, shoulders and hips are in a straight, vertical line.

 

Note:
Taller people may find that the drop keyboard mechanism interferes with the top of their legs. If this is the case, arrange to have the mechanism removed and the keyboard fixed, but make sure that the mechanism remains readily accessible because the next person to use the desk after you may need to have it refitted.

 

If you find that your elbow joint is open more than 100° call us for further assistance. If your elbow joint is less than 90°, then follow the flow chart below.

 

What type of desk do you use