Ergonomics Working with Computer

Learning basing principles of ergonomics – a science about providing of suitable work conditions and readjustment of work place for worker’s individual characteristics and abilities – it is possible to significantly reduce health problems. Taking into account these basic principles, prevent these inconveniences in your work place and work healthy!

1. Correct posture and back support

Perhaps it sounds tedious, but remember what your parents taught you: do not walk and do not sit with slouched back! If the back is bent, also the lower back is encumbered – these muscles are overstrained, tired, and they start to hurt and cause discomfort.

The head must be kept straight over the shoulders, the back should be straight, and it must be supported against the chair back (ideally if the curvature of lower spine is also supported against the chair back), knees must be slightly higher than the hips, but feet have to be based on the floor. A posture like this gives support for the spine. The pressure is put on the part of spine, which is meant for carrying of weight, therefore the vertebral discs, which can withstand the pressure for a short period of time, are not injured. If there is too much load on the vertebral discs, their liquid is squeezed out, and they become brittle, dramatically accelerating disruption of spine vertebrae.

Since every person has different body proportions, the more are opportunities to adapt the chair, the better, especially thinking about the length of human body and the position of its spine curvature. For people, who have short legs, footrests are very useful.

Experts believe that an opportunity to stop working every 20 – 30 minutes for about 5 minutes in order to take a walk is as important as the correct posture in the chair. Movements accelerate the circulation of blood and oxygen flow to the muscles, which have kept the body in the same position during working hours.

2. Keep your head, neck, and shoulders straight; eyes must be directed towards appropriate direction.

One of the most common mistakes, which computer users make, is that the body is not positioned at the right height and distance in relation to the computer. An objective is to easily work with the keyboard without bending and lifting your head.

Ideally if the chin is positioned around the centre of screen, and the screen is positioned 40 to 46 centimetres away from your eyes. This is a distance where the majority of people see well enough what is written on the screen without leaning forwards.

Leaning forwards or backwards puts pressure on discs of neck vertebrae. These discs, like discs of lower back, are the most vulnerable, as they are not protected by the ribs. Finding the appropriate distance from the screen and reducing its brightness also help to preserve eye muscles. There are no evidences that the usage of computer impairs the vision, but work with computer can fatigue eye muscles, cause irritation, and dryness in the eyes.

Reading materials should be placed in the holder next to the computer screen because constant head turning by more than 6 degrees in both directions fatigues musculature of neck and shoulders.

Another reason why do neck and shoulder muscles are strained is a phone. Avoid talking on the phone, holding it between the ear and the shoulder, as it strains the neck, causing pain of neck muscles and headache. Working at the computer it is better to use the phone with headset and microphone, rather than hand-held handset.

3. Keep your elbows along the sides, arms and wrists – straight

A neutral posture, where the arms and wrists, working with the keyboard, have the smallest load, is a posture, where the shoulders are relaxed, elbows are comfortably placed along the sides, and wrists are forming a straight line.

Wrists and fingers should be comfortably placed on the keyboard table so that wrists and fingers are not stretched, encumbering the musculature of wrists. The carpal tunnel syndrome, a painful nerve disease, which encumbers a grip, is the most serious consequences, which may be caused by prolonged physical load of fingers, wrists, and arms. The first symptoms of carpal tunnel syndrome is fatigue, numbness, or tingling in the fingers.

Experts believe that these problems can be prevented by the correct position of wrist pads, chair handles, and mouse. Also ergonomic keyboards and mouses can help to prevent these problems.

Computer and Vision

Human’s vision is not suitable for long lasting looking at the computer’s monitor. It can cause eye pain, blurred vision, and even headache. Among computer users complaints about eyes surpass complaints about pain in the wrist joints. Different researches show that approximately 70% of computer users suffer from vision impairment that is known as CVS or, in other words, Computer Vision Syndrome.

Overwork of Eye muscles

The most common symptoms of CVS are burning sensation in the eyes, blurred vision, and headaches. There may also be symptoms like tension and dryness in the eyes, slowed focus of image, discomfort during usage of contact lenses as well as pain of neck and back.

The cause of CVS is an excessive load and stress to your eyes. Closely looking at the monitor, muscle of vision focus is strained, and like any other muscle, also eye muscles hurt when they are overstrained. Because of long lasting looking at close objects, there may develop a condition that is known as spasm of accommodation. Consequences of this condition are impaired focus of image or even temporary myopia, which can last from few seconds to several hours.

Overwork of eye muscles may lead to such complaints of computer users as blurred vision after work or during driving a car. While such complaints may also be caused by reading and working with documents in the office, experts are sure that the computer monitor causes more harm to eyes.

When looking in the monitor, vision is more strained

The monitor causes greater effort of vision because the letters on the screen are not so clearly visible as they are on the paper. To make sure, look at the screen through the magnifying glass – the letter consists of pin-sized light flickering, and it does not have clear boundaries. Laptops with LCD screens are better for eyes because their image is sharper and thus clearer.

Researches show that dry burning sensation in the eyes is caused by the fact that, sitting at the computer, eyes are being blinked for about two-thirds less often than usually (usually eyes are being blinked for 21-22 times per minute, but when working with a computer – about 7 times per minute). In particular, it relates to users of contact lenses, therefore doctors recommend the use of natural tears, which are available at the pharmacy or optician’s shop.

The majority of doctors believe that too intensive work at the computer can cause only temporary eye ailments, for example, aching eyes, but some doctors believe that computer users are subject to more serious consequences as well, for example, to myopia. Although there are no clear evidences that computers form some changes in lenses or eye muscles, doctors warn that those, who have myopia in the family, have to be careful with the usage of computers.

Where to put the monitor?

CVS can also be caused by other reasons, for example, by the usage of inappropriate eye glasses or by wrong location of computer. People with inappropriate glasses are looking at the screen at the wrong angle. For example, users of bifocals often turn their head so that they can look at the screen through the lower edge of glasses, while myopic bend forwards, causing pain of neck, back, and shoulders muscles. The same is caused by the screen that is positioned too high or too low. The monitor should be placed at eye level, at arm’s length (about 80 cm).


  • Blink your eyes, as blinking protects your eyes from drying out;
  • Rest your eyes – draw away from the screen and look around or look out of the window; close your eyes time by time; it is not recommended to work with a computer without a break longer than 2 hours; make sure, that a break is at least 5 – 10 minutes long.
  • Place the monitor so that the light does not shine directly on the screen; if it is not possible, then cover it with a screen hood or some screen filter;
  • If possible, use a larger monitor;
  • The screen should be with dark letters and light background;
  • The screen should be placed no less than 80 cm from the eyes;
  • It is important to do a regular vision inspection; if you feel that your eyes hurt, dry, or blur, or your head aches, go to your eye doctor to prevent these symptoms.

What is a Computer Virus?

A computer virus is a program, which arbitrarily joins to other computer programs and during their action performs a variety of undesired actions: damages data, catalogues, computational results, deletes or pollutes a memory, and interferes computer’s performance in many other ways. Computer viruses usually multiply themselves by infecting disc data or system areas. If there is no anti-virus software in the computer, you can detect virus only then, when they have started an active performance.

A computer virus is a program, which spreads from one computer to other and interferes their performance. Computer viruses are often spread with attachments of e-mails, therefore never open an attachment if you do not know the sender or you do not wait for any attachment. Viruses may be hidden like attachments as funny pictures, greeting cards, audio files, or video files. Viruses also spread, downloading different files from the Internet – they may be hidden in some piracy software or in other files or programs, which you are downloading.

Computer viruses act similarly as biological viruses – they can be in the computer for long time without any evidence. Different viruses are activated differently, for example, there is a virus, which usually is activated, when 13th date falls on Friday. Also their expressions are different – there are viruses, which are pretty harmless, but there are also viruses, which can destroy all the data.

Signs, which distinguish viruses from programs:

  • Viruses are activated without user’s permission and are performing actions of programmer, not user;
  • They have ability to infect or change files or structure of discs;
  • By multiplying themselves they can spread to other files and systems;
  • Viruses are made by using the same programming languages, which are made by macros of such applications as Assembler, C, Visual Basic, Java, and others.

What is a Worm?

A worm is a computer code, which spreads without user’s knowledge. Worms are usually obtained with e-mail attachments – when they are opened, the computer is infected. Worms search for files, which contain e-mail addresses, for example, address books or temporary sites. Worms use these addresses to send infected e-mail messages and often imitate addresses of e-mail senders (pretending to be other sender), therefore it often seems that infected messages are known person’s messages. Then worms spread, using vulnerability of e-mail messages, networks, or operating systems, often taking over the system before the cause of problem is known. Worms not only harm computers, but also cause operational and stability problems of computer and network.

What is a Trojan Horse?

A Trojan horse is a malicious program, which hides in other programs. It gets in the computer, hiding in some legal program, for example, in some screensaver. Then it enters the code of operational system, providing hackers an access to the infected computer. Trojan horses usually do not spread themselves – they are spread by computer viruses, worms and downloaded software.