711 Introduction to Ergonomics

Computer Workstations

The monitor and keyboard positions, lighting, and seating are especially important in preventing work-related WMSDs and eye discomfort. Shared workstations should be easily adjustable so the screen and keyboard can be at the proper level.

Below are components of proper computer workstation design that you should address to maintain proper posture.

Work Surfaces

• Depth: Should be deep enough (typically 24–30+ inches / 60–76+ cm minimum) to allow proper keyboard positioning while maintaining a comfortable monitor viewing distance of approximately 20–40 inches (50–100 cm) from the eyes to the screen.
• Width: Wide enough to accommodate the keyboard, mouse (or other input device), and reference materials without crowding or awkward reaching. Minimum functional width often 27–30+ inches (68–76+ cm) for keyboard + mouse side-by-side.
• Height: Adjustable (ideally between ~22–30 inches / 56–76 cm for seated work) to fit the individual user or multiple users. The goal is to position the keyboard and mouse at or slightly below elbow height with shoulders relaxed.
• Additional Recommendations:
  • Provide sufficient leg room (knee clearance: minimum ~17–24 inches depth, ~20+ inches width; foot clearance deeper) so legs and feet can move freely without obstruction.
  • Avoid sharp or hard edges that contact wrists, forearms, or thighs.
  • Rounded or padded edges are preferred.
  • Consider bi-level or split surfaces (one for keyboard/mouse, one for monitor) for optimal independent adjustment.

Keyboards

• Design: Thin profile (low height) and detachable (separate from monitor) to allow flexible positioning.
• Positioning:
• Low enough so wrists remain straight (neutral posture) and shoulders relaxed.
• Elbows should be at approximately 90–120 degrees, close to the body.
• Keyboard should sit at or just below elbow height when seated with arms relaxed.
• Best Practices:
• Tilt the keyboard slightly negative (back edge lower) if possible to maintain neutral wrist posture.
• Use wrist rests sparingly and only for resting between typing — avoid resting while typing.
• Consider alternative keyboards (split, tented, ergonomic, or vertical) for users experiencing discomfort, wrist extension, or pronation issues.
• Position the keyboard directly in front of the user, centered with the body.

Mouse or Trackball

• Position: Place within easy reach, at the same height as the keyboard, close to the body to minimize reaching and shoulder abduction.
• Usage: Keep the mouse close to the keyboard; avoid extended reaching.
• Alternatives: Trackballs, trackpads, or other pointing devices can reduce repetitive gripping and forearm pronation for some users. Consider ambidextrous or vertical mice for comfort.
• Best Practices: Use a mouse pad with wrist support if needed, but prioritize proper overall posture over reliance on pads.

Monitors

Chairs

• Back Support: Adjustable lumbar support to maintain the natural curve of the lower back.
• Seat Pan: Adjustable height and depth (seat pan should allow 2–3 fingers of space behind the knees).
• Knee Angle: Approximately 90–100 degrees (or slightly more). Use a footrest if needed to achieve proper posture without pressure on the thighs.
• Base: Rolling base with five prongs (casters) for stability and mobility.
• Armrests: Adjustable (height, width, depth) and padded; should allow shoulders to remain relaxed with elbows close to the body.
• Best Practices:
• Feet should be flat on the floor or supported by a footrest.
• Sit back fully in the chair with back supported.
• Avoid "perching" or sitting too far forward.
• Test chairs for comfort over extended periods before final selection.

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