Ergonomics is the science of fitting the job and the work environment to the worker.

The office environment has undergone dramatic changes in the last two decades. Some of the changes, including the introduction of computers, have resulted in benefits such as increased efficiency. However, these changes have lead to work habits that are more sedentary than in the past.

One of the results of this new work pattern is an increase in the number of painful conditions involving the back, neck, wrist and head. The major factor contributing to these injuries is the long period of time an employee sits in the chair. Another is the increase in repetitive motions required with the use of keyboards. The arrangement of lighting and VDT screens also contributes to the incidence of work-related complaints.

Setting Up an Ergonomic Computer Work Station at Home

Due to the need for many of us to work from home because of COVID-19, we have attached a video with guidance to set up computer stations at home. Many of us do not have ergonomically friendly home work spaces and with the unknown length of time we will be working from home we should all make our workstations as ergonomically friendly as possible in order to decrease or eliminate the stress placed on our bodies.  

A computer workstation at home may be a laptop computer on a couch, bed, or kitchen table. As comfortable as some options may sound, using an improper workstation setup for an extended duration can cause awkward posture, which can increase the risk for ergonomic related injuries (or musculoskeletal disorders such as tendonitis and carpal tunnel syndrome). It is important to set up your workstation as best you can to prevent injury regardless of where you might work.

  • Use a good chair (if possible). If you do not have a good chair, add pillows or towels for back/leg support.
  • Raise your seat (most kitchen tables and desks are too high). Use a pillow or towel as a seat cushion if needed.
  • Support your feet on a phone book, step stool, etc. if they do not firmly touch the ground while sitting. Both hips and knees should be at a 90° angle with feet flat on the ground.
  • Raise your monitor using books, old shoeboxes, etc. so the top of the monitor is at or slightly below eye level.
  • Your monitor should be about an arms length away from your body.
  • Use an external keyboard and mouse. It is essential that the monitor be separated from the keyboard/mouse. Shoulders should be relaxed with the elbows around 90° angle.

Work Station

Work station evaluations can help ensure that an individual employee has enough flexibility to ensure optimum comfort, mobility and organization. Three variables should be considered in the design of any work place: chair height, work surface height, and length of required reach. These should all be adjustable to accommodate variations in employee size and strength.

  • The height of the chair should allow the hips and knees to be at right angles to the body with feet on the floor. The seat should be about two inches less than the distance from the crease of the knee to the floor.
  • The backrest of the chair should support the small of the back.
  • The height of the desk, table, typewriter or computer screen should be adjustable so the employee has plenty of leg space and can sit back in the chair with forearms parallel to the floor. If the chair is not adjustable, it can help to place a footrest (a telephone book works) for better support. Placing a book under the Video Display Terminal can also help correct the height of the computer screen.
  • Organize paperwork so that reaching for it may be kept to a minimum.
  • Take 10 to 15 minute breaks every 2 hours to help relieve eyestrain and fatigue associated with VDT use. Varying the work routine can minimize the chance of injury or strain.

Posture Problems

Why is sitting bad for you?

Sitting for long periods of time has two important effects on the human body: an increase of muscular tension and a constriction of the spine. Both contribute to pain in the back and neck.

Muscles can be involved in two types of activity: dynamic effort and static effort. Dynamic effort is characterized by movement; the muscle fibers are contracted and relaxed rhythmically. Static effort occurs when a muscle is contracted and held in the contracted position for some time. Bloodflow is restricted in a contracted muscle.

Dynamic effort, such as walking, is easy to sustain for long periods of time because fresh, oxygenated blood flows in a muscle every time it releases. Static effort, however, results in a continual deficit of blood supply to the contracted muscle, so a statically held muscle cannot rid itself of metabolic waste products. It is these waste products which produce the feelings of pain, tenderness and fatigue. Most jobs have a combination of dynamic and static effort tasks. Even individual tasks can have elements of both; for example, typing on a keyboard involves the fingers dynamically and the arms and shoulders statically. It is the statically held muscles that eventually become painful and sore.

A second factor contributing to occupational back pain concerns the orthopaedic aspects of the sitting posture. The human spine has a set of natural curves that become distorted when sitting. The lower back, or lumbar region, which normally curves forward, becomes bowed out. The backward tilting pelvis puts pressure on the intervertebral disks and nerves. The disks are fluid-filled sacs which act as cushions between the vertebrae. If the disks degenerate, then the resulting pressure on the spinal bones and nerves can cause pain.

 

How is back pain treated?

As the causes of back pain are many, there are many approaches to treatment. Medical doctors are often consulted, as well as orthopaedic specialists. If surgery is not warranted, they will often recommend a regime of rest, painkillers and physical therapy. Physical Therapists are often included to oversee the physical exercises. Many people prefer the services offered by chiropractors for their back pain. For some, this treatment offers immediate relief and has the added benefit of being drug-free. Acupuncture has relieved some people, as well as massage therapy. There is no final consensus as to the best treatment for back pain. Different individuals will find help in a number of different treatments. Nevertheless, most people experience the largest amount of pain relief through a regular exercise plan of walking or swimming. There are many who find a cessation of symptoms through this action alone.

Repetitive Motion Injuries

Many repetitive motion injuries such as tendonitis or carpal tunnel syndrome in the wrists are the result of performing repetitive tasks for long periods of time on a daily basis.

Carpal Tunnel Syndrome (CTS) is associated with many jobs which involve repetitious motion of the wrist. The use of computer keyboards is a potential cause of CTS for many workers. CTS is a painful condition of the wrist and forearm that is a result of repetitive hand motion. Its cause can be traced to a u-shaped cluster of bones at the base of palm which forms the base and sides of the carpal tunnel.

A tough ligament forms the roof of the carpal tunnel. Running through the tunnel are the flexor tendons and the median nerve, which operate the thumb and the first three fingers. CTS occurs when overwork, such as prolonged gripping, repetitive flexing of the fingers, or constant vibration causes the flexor tendons to become inflamed, putting pressure on the median nerve. There are other, non-occupational, causes of pressure on the nerve which can result in CTS, such as the normal aging process, fluid retention (particularly during pregnancy), or a previous bone dislocation or fracture. Irritation resulting from these non-occupational factors can aggravate occupational CTS.

One reason that CTS is often unrecognized as work-related is that the early symptoms usually occur at night. These early signs can be pain, tingling, or numbness in the hand or forearm. As the condition becomes more advanced, there can be a loss of sensation in the hand or stiffness in the hand and fingers, with a gradual loss of grip strength and control of the thumb and first three fingers. Left untreated, CTS can cause permanent nerve damage, with a deterioration of the large muscle of the thumb. Because of the variety of symptoms, CTS can be misdiagnosed, particularly as arthritis. There are several tests used by physicians to diagnose CTS.

 

How is CTS treated?

In its early stages, CTS can be treated conservatively, without surgery. Relief in mild cases can be provided with stretching exercises. Simply stopping work every hour to gently rotate the wrists and arms to increase circulation and relieve muscle tension can reduce the stress on the carpal tunnel. Further steps include the wearing of a wrist splint at night and, if possible, on the job. Icing the wrist can sometimes reduce the symptoms. Anti-inflammatory drugs such as Motrin and Advil can be used to reduce the tendon inflammation; cortisone shots can also be administered.

In cases where symptoms are so advanced that they do not respond to any of the above treatments, carpal tunnel release surgery may be the only recourse. This surgery divides the transverse ligament to open up the carpal tunnel. Although initially successful, surgery may not be the cure. Continued pain, tenderness, and a perceptibly decreased grip are not unusual. Scarring of the divided ligament may put pressure on the nerve again, causing a re-occurance of symptoms.

 

Can CTS be prevented?

Obviously, the real key to eliminating CTS is prevention. Workers should make a conscious effort to use proper posturing and grips. The posture of the wrist should be in line with the hand to prevent pinching with the carpal tunnel. Avoid using bent (flexed), extended or twisted wrist positions for long periods of time. Workers using keyboards on a continual basis should change the angle of their chair to properly align the wrists. If the job consists of varied work, switch tasks often. If constant repetition is required, rest the hands periodically.

Early detection of CTS is particularly important since it can be more easily treated in its mild stages. Don't allow the pain to reach intolerable levels before seeking treatment. On-the-job pain that lasts more than an hour should be interpreted as a danger sign. Symptoms that occur at night should also be considered a warning. Always report such pain to a supervisor.

Vision Problems

Human eyes were made for most efficient seeing at a distance. But, as you know, VDT use demands using your eyes at a closer range, usually intensely, over long periods of time. This alone can strain your eyes and may cause vision problems to develop or aggravate existing vision conditions. Effects on the eye vary depending on the individual and the work station. Some of the factors influencing this are:

Eye Fatigue: Viewing VDTs at a close range for long periods can be very tiring, and over a long period of time may cause temporary deterioration of vision. VDT operators should take periodic breaks in open areas away from their machines, in addition to alternating an hour or two of screen work with an hour of another kind of work that would allow viewing from a greater distance and more body movement. Two hours is the maximum time that should be spent doing continuous screen work.

Glare: Eyestrain can be caused by improper positioning of the terminal in relation to surrounding office lighting, windows, shiny surfaces and background colors. Glare from a VDT screen that reflects surrounding light can be reduced by using nonreflective glass as well as altering the lighting structures in the vicinity of the screen. Installing blinds or awnings on the nearby windows, relocating the machine for better lighting or relocating the light fixtures can significantly reduce glare from the glass of the VDT.

If a terminal is positioned against a background that makes it difficult for the eyes to adjust to the images on the screen, such as a white wall or a window, strain can also result. In this case, the pupils are adjusting to the bright background rather than to the darker screen, and the images on the screen become difficult to see. The VDT operators often compensate by bending their heads or turning their bodies to block the light, causing muscle strain as well.

Successful solutions include:

  • dimming the lights
  • changing the location of the VDT
  • painting or covering the wall facing the terminal in a color or texture that reflects less light
  • installing a dark screen or partition behind the machine

But before changes are made in any office, it is important to discuss the proposals with fellow employees, taking into account their preferences. Darker lighting, walls and windows may be more depressing and stressful than the original problem.

 

Eyeglasses and contacts

Particular problems occur with workers who wear glasses or contact lenses. Glasses overcorrect an operator's eyes for the distance for which they are used with a VDT. Most glasses correct the wearer's vision for a reading distance of 10-13 inches, whereas VDT viewing distances tend to be further, usually 16-20 inches. Workers may find it necessary to be fitted with special lenses designed for their normal viewing distance from the screen.

 

Screen character size and color

The size of the screen and of the characters plays an important part in adding to, or detracting from, the comfort of the operator. A larger screen with a viewing distance of more than two feet, with a character height of at least 3/16 of an inch is optimal.

It is also best to avoid use of terminals where there is a noticeable 'flickering' of the characters on the screen. All VDTs emit light produced by phosphors which fades rapidly and must be constantly replenished. Unless the rate of replenishment is at least 60 times per second, this flickering may be discernible to operators. Such terminals require more concentration and hence, result in more strain.

 

What can prevent these VDT problems?

Chairs, keyboards and desks

The most important thing to look for in a chair is adjustability. The second most important thing is to take the time to adjust it to your needs. You should be able to adjust the height so that both feet can rest on the ground. There should be a back rest with good lumbar support for you lower back, which should also be adjustable. Backrests that lean back in a rocking motion are also a good feature, as they give the back muscles a chance to move. The presence of armrests is up to the operator's preference; the best chairs have armrests that are removable and (yes!) adjustable. If you have the opportunity to shop for a new chair, ask the retailer if they will let you take the chair on trial. The only way to really tell if the chair is right for you is to sit in it through the day.

The keyboard should rest at a height that is comfortable for your arms and shoulders. Put your hands on your keyboard as if you were going to type and check your position. You do not want any strong bending or flexing at the wrists, nor do you want to have your shoulders scrunched up high. Sometimes, the keyboard can be lowered by installing an adjustable, sliding tray underneath the workstation. Wrist relief can be sought by having something soft to rest your wrists on in front of the keyboard; a small, rolled towel will often work well. Also, make sure your chair is adjusted properly. If the chair must go up so you can reach the keyboard comfortably, then get a foot rest to go under your feet. Lastly, take a close look at your desk, some of the newer models have adjustable heights.

Your computer should not be placed with the monitor too close in front of your face. Placing it at a distance protects your eyes from strain. If you have a mouse, place it where you can manipulate it without strain on your arm or wrist.

Lighting

Use proper lighting. It can have a significant impact on your visual comfort and efficiency. The lighting for VDT operation should:

  • Be about 20 to 50 foot candles, which is about half the level used in most offices. Lower lighting can be achieved by using fewer bulbs or fluorescent tubes, installing lower intensity tubes, or using dimmer switches.
  • Match as closely as possible the brightness of the surroundings with that of the VDT screen for optimum comfort and efficiency. However, the contrast between the characters on the screen and the screen background should be high.
  • Minimize reflected glare on VDT screens by keeping them away from windows and other sources of bright light. Use window shades or drapes to block out excessive sunlight. Antiglare screens are also available.

Breaks

Take a break! Many authorities recommend a 15 minute alternate task break every hour if you are a full time user. If you have any duties that take you away from the computer terminal, divide them up through the day, so as to prevent long stretches of work at the terminal. If you have no alternative duties, take at least ten minutes out of every hour to stand and stretch - movement is good for the body!

Exercise

It is a good idea to practice a regular schedule of exercise to offset the sedentary lifestyle of the office. Whatever your choice of exercise, remember that a little done regularly is better than a lot done infrequently. Scheduling in twenty minutes a day, or an hour's worth three times a week can have a dramatic effect on your health, and, ultimately, on your work performance.

Noise and Hearing Conservation

The noise level in any area should be low enough not to cause interference with communication or distraction from work. Environments in which excessive noise levels are present can result in the aggravation of hearing impairments and hearing loss. Adequate personal protective equipment should be available in all excessively noisy areas. Any areas that expose employees to noise levels of 85 decibels or higher for a constant 8 hour period require annual audiometric testing of the affected employees.

 

 

Get a Ergonomic Evaluation

Schedule a work-site specific consultation with a Certified Ergonomic Evaluation Specialist
Contact safety@uvm.edu