Ergonomics

Ergonomics is defined as the multidisciplinary study of the interactions between a worker and their work environment. The goal is to design and arrange equipment or tools such that workers are able to interact with them in a healthy, comfortable and efficient manner.  Examples include the placement of computer screen, keyboard, mouse, chair, desk or other equipment in an office or height of work benches and equipment in work shops.

Poor workplace designs can present ergonomic risk factors called stressors. These stressors include but are not limited to repetition, force, and extreme postures, static postures, contact pressure, vibration and cold temperatures. Well designed work stations, i.e. fitting the work to the worker, helps lessen muscle fatigue, reduces the number and severity of work-related injuries and increases productivity.

Elements of Ergonomic Programs – A Primer on Workplace Evaluations of Musculoskeletal Disorders

UNC Asheville Ergonomics Program

Ergonomics & Computer Use

Setting Up a Comfortable, Healthy Workstation

Typically, there’s nothing wrong with using a basic workstation, but when you spend most of your waking hours sitting at that desk, you may want to consider making it a more comfortable space, for long-term health. Prolonged, intense computer use may cause pain or fatigue in your hands, wrists, arms, shoulders, upper back or neck.

Without proper computer set-up and use, there are many problems that may result. Tendonitis is the most common problem, involving tendon inflammation and localized pain in the elbow, forearm, wrist or hand. Bad posture can cause fatigue, muscle strain, and, in later stages, pain. Back pain, one of the most common complaints of older men and women, is usually the result of years of bad posture. Sit up straight to promote good health.

Keyboard and Mouse Position

When positioning your keyboard and mouse, you should keep in mind that you want to reduce unnecessary strain in your fingers, wrists, arms, and shoulders, keeping them in as neutral and relaxing a position as possible. While you’re typing, your wrists should not be resting, but held up in line with the backs of your hands. This reduces strain to your wrist that may result from holding it at an unnatural angle, and allows you to move your arms to reach the keys, rather than stretching your fingers to reach them. Use a foam pad or towel in front of your keyboard to rest your wrists and forearms while you’re not typing. Because you want your arms free to move your hands around the keyboard while typing, you should only use armrests on your chair when you’re not typing. Holding your wrists up is not very tiring because most people are not actually typing continuously for long periods, so you’ll have plenty of time to rest your arms while you think about what to type next.

Your fingers should be in a straight line with your forearm. This is made easier by tilting the back edge of the keyboard down (the reverse of typical keyboard tilts). The keyboard should ideally be just above your lap so your elbows are bent at least 90°. If you can’t move your keyboard, try adjusting the height of your chair, though this may cause problems if you can’t adjust your monitor accordingly. If your wrists ache or tire, look into buying an ergonomic keyboard that angles out from the center, making it easier for you to keep your hand and forearm in a straight line. Aching and strain caused by typing may be reduced by typing more gently – avoid banging the keys.

Hold the mouse lightly, don’t grip hard or squeeze it, and position it close to the keyboard so you don’t have to reach. If you’re troubled by pain in your wrist and forearm, use an ergonomic mouse that’s moved with a finger instead of the wrist. Keep your arms and hands warm – cold muscles and tendons are at greater risk of injury.

Monitor Position

Your monitor should be slightly below eye level and straight ahead, not to one side. It should be about arm’s length away from your face so you can easily read the screen, not leaning your head forward, which puts strain on your neck. To protect your eyes, reduce the glare from the monitor’s screen by turning off overhead lights or closing the window blind. Glare screens are also available.

Chair Position

The position of your chair is important to help you maintain good posture. Good posture involves keeping your bones and muscles in line, which promotes efficiency, endurance, and an overall feeling of well-being. If you slouch, your bones are not properly aligned, and your muscles, joints, and ligaments take more strain than they were meant for.

Your chair should support your back in an upright and relaxed arch position. If the back of your chair doesn’t provide enough support, try putting a rolled towel or cushion between the small of your back and the chair. The height of the chair should allow you to have your feet resting firmly on the ground, with your thighs roughly parallel to the floor. If your chair is too high, use a footrest to keep your knees and hips level.

To make sure your posture is correct, sit with a neutral spine position, with your hips at about 90°. If your back is straight, supported by back and abdomen muscles, you can relax your shoulders without slouching.

Desk Stretching Exercise

Prolonged periods of sitting at a desk, combined with long commutes, can cause loss of flexibility in the muscles in your legs, hips, back, shoulders and neck. To prevent injury while sitting at your desk, try these desk-stretches throughout your day.

  • Finger Stretches
  • Wrist Flexion
  • Trunk Rotation
  • Standing Calf Stretch
  • Arm Rotation
  • Ankle Rotation
  • Forward Lean
  • Wrist Extension
  • Back Arching
  • Shoulder Shrug
  • Head Extension
  • Neck Rotation

Repetitive Strain Injury (RSI)

Repetitive Strain Injury results from forceful, awkward, and/or repetitive use of your limbs, producing damaged muscles, tendons, and nerves. The severity of RSI cases varies widely. Tendonitis is the most common example of RSI, while carpal tunnel syndrome is a more rare and serious disorder. RSI occurs frequently among computer users, musicians, lab workers, and other people with occupations requiring repetitive movements.

Although RSI is a broad term that encompasses several disorders, general symptoms include tingling or loss of sensation in fingers, inability to grasp objects between thumb and fingers, decrease in the size of hand muscles, and pain in the wrist, elbow, shoulder, or neck. If using a computer is painful, but necessary, try to vary your work activities so you’re not using the keyboard and mouse for long periods of time. You can make adjustments to your workstation to make yourself more comfortable.

In order to prevent RSI, adjust your desk and computer area to promote good posture. Remember that the human body is not made to sit still for long periods of time, so get up and move around as much as you can. This may involve taking 30-60 second breaks every ten minutes or so, and getting up to walk around and stretch your muscles every hour. You can also vary your motions by changing tasks. Type for a while, then read, take notes by hand, or organize papers. Stretching your wrists, shoulders, and neck will help reduce muscle tension. Roll your shoulders, rotate your head from one side to the other, massage your shoulders, and stretch your wrists by pulling the fingers back toward the wrist. When you’re typing, be sure not to bang on the keyboard, and avoid lazy wrists.

Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) and thoracic outlet syndrome are two of the most common repetitive strain injuries. These conditions are disorders of the tendons, nerves, arteries, or veins occurring at the wrist and upper arm, respectively. In CTS, repeated bending or use of the wrist and fingers results in the compression of the median nerve (runs along the palm side of the wrist) causing intermittent numbness, tingling, and pain in the side of the hand including the thumb through the inside of the ring finger. The hand’s communication with the brain is disrupted and the fingers have difficulty sensing temperature and gripping objects. You may also notice swelling of the hand and forearm. Pain and numbness in the fingers not only occur while typing, but also at night. The advanced stage is characterized by decreased muscle bulk in the thumb area and decreased sensation.

Ergonomic Assessments

Computer Workstations

The way we sit, stand and move at our computer workstation can have a direct correlation to back, neck, arm and hand injuries. Often, minor adjustments in posture, furniture and reducing the duration of time spent performing a single task can minimize the risk for such injuries. With the time spent using computers at work and at home continuing to grow, it is important that everyone has basic knowledge of ergonomic principles related to the computer workstation.

Everyone’s physiology and workstation setup is unique, so the self-guided evaluation is the most effective first step. The vast majority of improvement can be made with simple adjustments by using the checklist (below) as a guide, watching the self-guided video, or requesting a prevention focused work space assessment by contacting EHS at (828) 251-6038.

OSHA Ergonomic Evaluation Checklist – Computer Workstations eTool

WSDLI Office Ergonomics Self-Guide Video

OSHA E-Tools Purchasing Guide Checklist

Work Associated with Physical Tasks

Several ergonomic assessment tools for physical tasks can be found at the Washington State Department of Labor & Industries website.

NIOSH Lifting Equation

The National Institute for Occupational Safety and Health (NIOSH) Lifting Equation mobile application, NLE Calc, is a tool to calculate the overall risk index for single and multiple manual lifting tasks. This application provides risk estimates to help evaluate lifting tasks and reduce the incidence of low back injuries in workers.

NIOSH Lifting Equation App

The NIOSH lifting equation calculator (NLE Calc) is based on the Applications Manual for the Revised NIOSH Lifting Equation (Pub No. 94-110) and can be used to calculate the recommended weight limit (RWL) and lifting index (LI) for single or multiple lifting tasks. The LI is an index of the relative physical stress for performing a particular lifting task, while the composite LI or CLI is an index of the overall physical stress for performing multiple lifting tasks. NIOSH recommends an LI and CLI of 1 or less for protecting workers from physical stress related to development of low back disorders. Please refer to the Applications Manual for the Revised NIOSH Lifting Equation publication for examples and details on how calculations are performed and what the results imply.

Applications Manual for the Revised NIOSH Lifting Equation