Repetitive Strain Injury (RSI)

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Repetitive Strain Injury (RSI)
ECE 417/617Elements of Software Engineering
Stan Birchfield Clemson University
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You are a computer athlete
A dangerous occupation
This is also dangerous
As a typical computer user, you walk several
miles each day on your fingertips
(250 keystrokes / min) (2 in / keystroke) 4
hours 2 miles
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What is RSI?

• Repetitive Strain Injury (RSI)
• is pain or nerve problems in upper extremity
  (hands, arms, or shoulders)
• can also include neck and back
• is a soft tissue disease (muscles and nerves)
• is an overuse syndrome
• Symptoms
• burning, numbness, tingling, pins-and-needles
• dull aching OR specific, intense pain
• Controversial
• many deny it exists
• sufferers receive little support from employers

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The cost of RSI

• 20 billion per year Information Week, Nov. 9,
  1992
• 29,000 average compensation
• accounts for 60 of all job-related injuries
  Department of Labor
• Approx. ¾ of all jobs require using a computer

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Carpal tunnel syndrome

• Carpal Tunnel Syndrome is a specific type of RSI
• Swelling increases pressure on nerves to fingers
• Problem is only in wrist
• Most RSI is more widespread (neck, back, arms,
  shoulders)

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What causes RSI?
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Cantilevers
stress
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Bad posture
pronation
slouching
ulnar deviation
dorsiflexion
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Anatomy of hand nerves
brachial plexus

• Thoracic outlet
• b/w collarbone and rib 1
• Brachial plexus
• braided nerves
• also supplies shouder, neck, and arm muscles

• Three nerves
• Medianthrough carpal tunnel
• Ulnarfunny bone
• Radialextensor muscles

top view
bottomview
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Traditional solutions

• Surgery
• Wrist braces
• Anti-inflammatory drugs
• Pain killers
• Cortisone shots
• Ergonomic keyboard, mouse, etc.

Why should you be cautious?
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Keep in mind

• Long-term problem ? long-term solution
• The pain may move
• The pain may go away temporarily, even though the
  problem is not solved
• Musculoskeletal system (muscles, tendons, and
  bones) adapts
• Body is meant to move
• Ergonomics are important, but beware of trying to
  achieve perfect posture

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Outline of a solution

1. Stretching
2. Movement
3. Strength

Also posture, massage, remove wallet from back
pocket,hot/cold treatment, ergonomic keyboard /
mouse, better chair, ...
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Computer vision syndrome (CVS)

• Computer screens are different from printed
  material
• Contrast is not sharp
• Edges of characters are not well-defined
• Our eyes have difficulty focusing
• Instead, eyes drift to the resting point of
  accommodation (RPA)
• Eyes involuntarily move to RPA, then strain to
  regain focus
• Results
• Fatigue, tired eyes from continuous flexing
• Dry eyes from not blinking enough

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Final advice

• You think RSI will never happen to you
• When you start feeling pain, you will
• ignore it
• learn to bear it
• expect it to go away on its own
• When your pain disappears temporarily, you will
  think problem is solved
• When your pain intensifies gradually, you will
  continue to ignore it until it is serious
• ? Pain is your bodys way of telling you that
  something is wrong! Be aware! Do not ignore the
  symptoms! Seek help when the pain first appears,
  before it becomes a serious problem!

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For further reading

• Damany and Bellis,Its Not Carpal Tunnel
  Syndrome!
• Pascarelli, Repetitive Strain Injury