How can a Computer Monitor become Problematic?

• If a computer monitor is not positioned properly, it can lead to numerous types of chronic injury, especially of the neck, eyes, and back.

• Computer monitors are often positioned too low for its user, which may bring about a downward eye glaze, an increased neck angle, and forward bending of the upper back.
• With the neck and upper back in this position, stress on the spine significantly increases.
• This position also brings about fatigue much earlier throughout the workday.
• Vertical gaze direction, ocular surface area, and viewing angle are all affected as well.

• Computer monitors that are positioned too high (i.e.: above the horizontal of eye gaze) lead to shortening of the neck and upper back muscles beyond their optimum lengths and lengthening of the muscles in the front of the neck.

How should I Properly Position my Computer Monitor, and why is this Important?

• The monitor should be positioned directly in front of you at an arms length away.  Make sure it is perpendicular to the window, if you have one in your office, in order to avoid glare on the screen.

• In order to minimize the load on the musculoskeletal system, the eye gaze inclination to a visual target, in this case the computer monitor should be approximately 6-9º below the horizontal (about 10 cm below eye height).

• Large-sized monitors for convenient use of larger icons and symbols will likely necessitate a gaze at the proper angle and a more erect body posture.

• Working within proper viewing angles will minimize the surface of the eyeball, which, in turn, will help the eye to retain its moisture and be better equipped to perform computer work.

Problems Caused by Computer Keyboards

• Computer keyboards can increase carpal tunnel pressure whenever the hands deviate sufficiently from a neutral position, which can prevent the free flow of fluids into the palm of the hand.
• Research has shown that sustained increases in carpal tunnel pressure of > 30 mm Hg disrupt blood flow and impair the nerves of the wrist and hand.  Carpal tunnel pressure is typically > 40 mm Hg when flexing or extending the wrists during typing tasks.
• Maintaining this position for an extended period of time can lead to injury of arm and hand musculature as well as the tendons and nerves within the wrist and hand.

• In addition to increased carpal tunnel pressure, repetitiveness and exaggerated force application when using a keyboard are risk factors directly related to repetitive stress injury. 

• The standard, flat design of a typical keyboard requires users to make unhealthy postural adaptations to conform to the keyboard, and when using a computer keyboard for > 5 hours, the likelihood of injury significantly increases.

Tips for Proper Keyboard Use

• Using a downward tilting keyboard tray (with no more than a 15° tilt):
• significantly reduces wrist extension while typing and at rest
• considerably improves both low back pain and shoulder pain
• wrists and hands maintain a more neutral position > 60% of typing time

• Open or fixed keyboards are better ergonomically than standard keyboards. 
• Open keyboards (with keys that slope up at an angle from the keyboard base) cause significantly less twisting of the wrist when typing.
• Fixed keyboards (with keys split down the middle and angled) decrease the amount of wrist motion from left to right and maintain the wrist in a more neutral position.

• Don’t use a wrist rest!
• Research has shown that using a wrist rest doubles the pressure inside the carpal tunnel
• This is because the floor of the carpal tunnel is a more flexible ligament that transmits external pressures directly into the carpal tunnel.

• Keyboard keys should not stick or need excessive force to be operated.

• Longer horizontal distances between the keyboard and the edge of the desk keep the wrist in a more neutral position and reduce chronic injury.

How Does Mouse Use Lead to Discomfort?

• When using a mouse, workers typically extend their arms, raise their shoulders, and/or position their elbows far away from their body for several minutes at a time without awareness of their position or breaks from mouse use.

• Mouse use has been associated with an increased risk for upper extremity musculoskeletal disorders, such as carpal tunnel syndrome, because carpal tunnel pressures during mouse use are typically greater than pressures known to alter nerve function and structure.
• Elevated carpal tunnel pressure during mouse use is an effect of both wrist extension and excessive fingertip force applied to depress the button and grip the sides of the mouse.

• It has been estimated that workers use a mouse an average of 78 times per hour, accounting for about 23.7% of computer work time.

• The highest levels of EMG activity during computer work occur in the forearm during mouse activity compared with other computer tasks.

How Can I Prevent Symptoms?

• Use an external mouse, and make sure the mouse is at elbow height.

• Optimal positioning of the mouse is next to the keyboard on a sliding keyboard tray.

• Minimize prolonged dragging tasks and frequently perform other tasks with the hand used for the mouse.

• Consider placing the mouse on the left side of the keyboard as it reduces the postural constraints of the upper extremity using the mouse.

• A quick-fix solution is using a “mouse bridge,” which is a stand on which the mouse sits on top of the number keypad.

What are the Effects of Improper Office Lighting?

• Inadequate office lighting may cause visual discomfort, which can lead to neck, shoulder, and/or forearm pain.

• Severe headaches account for 48% of work-related aches and pains and are directly correlated with problematic office lighting.

• Computer workers with improper office lighting may experience symptoms of visual discomfort such as red-eye, a gritty sensation within the eye, and sensitivity to light.

• Visual discomfort has been proven to interfere with employee’s job performance and overall productivity.

What are the Causes and Effects of Glare?

• Excessive office lighting via natural means (i.e.: bright sun coming through the window) or artificial means (i.e.: overhead lighting or one’s own reflection when wearing light-colored clothes) can act as a major source of glare, which can become a significant problem.

• Glare can significantly reduce visibility depending on the proximity of the source of glare to the viewer.

• Glare has significant correlations to eye focusing problems and tired eyes and has been shown to lead to an increased number of typing errors.

Tips for Safe Office Lighting

• The Human Factors and Ergonomics Society recommends that any luminous source within the computer user’s field of view should not exceed three times the screen luminance. 

• There is considerable literature to support the fact that the room’s surrounding light should be brighter than the central target, in this case, the computer display.

Why is Proper Lighting Important?

• Appropriate office lighting has been shown to increase creativity potential, especially if the office contains windows.

• Higher visual acuity due to optimal office lighting conditions leads to better performance and/or lower levels of eye strain.

Facts about Prolonged Sitting Postures

• Research suggests that joint forces in the lower back are significantly higher when in a prolonged seated position as opposed to a prolonged standing position. 

• Seated work increases the risk for low back pain due to sustained static loads imposed on the spine.

• Sitting for prolonged periods of time also causes continuous compression on the intervertebral discs, which hampers the flow of fluid and decreases joint nutrition.

Why is Office Seating Problematic?

• When sitting, it is very easy to slump into a posture which significantly changes the shape of the spine and drastically increases the pressure on the intervertebral discs in the low back.
• Slumping posture can result in low back pain and over a prolonged period of time can cause more serious back problems.

• Many office chairs have traditional, padded, fixed-height lumbar (low back) supports that are unlikely to provide a comfortable or appropriate seat for people of various body types.

• People do not always prefer chairs that correspond to their body’s characteristics and therefore fail to adjust their chairs accordingly.

What Type of Office Chair is Optimal?

• Using a dynamic (adjustable) chair as opposed to a fixed chair is an easy way to help prevent low back pain associated with sitting.

• Dynamic chairs allow opposite movements of the seat and back support, which accommodate a reclining posture, allowing for relaxation of the back muscles.

• Office chairs should have a lumbar (low back) support positioned between the second and fifth lumbar vertebrae (lower four vertebrae of the spine). 

• A chair should allow for easily varied sitting postures, in order to allow the spine to move rather than attempting to constrain people to an ‘ideal’ sitting position.

All above information from N. Baker & K. Jacobs (1999) Boston University. Sargent College

Ergonomic Strategies for Using a Briefcase

Effects of carrying a heavy briefcase

· Heavy briefcases worn over one shoulder cause uneven weight distribution across the back muscles and may restrict blood flow at the shoulder.

· Heavy briefcases place extra pressure on the nerves of the neck and shoulders and can result in pain in the neck, shoulders, and lower back. Pain may be described as pins and needles, tingling, stiffness, numbness, or tightness.

· Avoid carrying a briefcase with your thumbs—this will cause excess pressure on the joints in your hands/fingers.

Tips for selecting the right briefcase

· Consider a wheeled briefcase.

· Choose a briefcase that is proportionate to your body size and no larger than what is needed.

· Avoid selecting briefcases made of heavy material such as leather. This only adds extra weight! Instead. Select a briefcase made of lighter materials such as microfiber and nylon

· Select briefcases with built-in compartments. This will help to distribute the weight more evenly.

· Straps:

o Select a briefcase with padded straps to distribute equal weight across your shoulder.

o Avoid thin and long straps; straps should be wide and adjustable. Ensure that any pressure caused by the straps does not cause discomfort.

Tips for packing your briefcase correctly

· Make time every evening or morning to review the contents of your briefcase. Remove unnecessary duplicates such as extra pens and notebooks. Only keep the items needed for that day and leave other items at home or in your car.

· Consider purchasing an extra set of accessories (e.g., power cord and battery) to leave at your office so you do not have to regularly carry heavy items back and forth between your home and office.

· Clip your cell phone to your waistband.

· Always pack the heaviest items at the bottom of your bag and make use of built‐in compartments to distribute the weight.

Tips for carrying your briefcase correctly

· Briefcases with short handles:

o Switch positions frequently to avoid fatigue from muscle overuse.

· Briefcases with shoulder straps:

o Place the strap diagonally across the opposite shoulder to help distribute the weight evenly across the back.

o Square your shoulders and avoid lifting your shoulders to keep the shoulder strap from slipping.

o Alternate shoulders by switching the briefcase from side to side.

o While carrying your briefcase, consider resting it on the floor, counter or railing when waiting or standing in line.

These tips were provided by Brittney Nichols, OTS brittneynichols@gmail.com), Priscilla Nova, OTS (priscillanova@gmail.com) and Karen Jacobs, EdD, OTR/L, CPE, FAOTA (kjacobs@bu.edu) of Boston University

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