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Consider the spine: it bears our weight, keeps us
stable and lets us move in myriad ways. Thanks to this column of
soft tissue and bone, we can walk, lift a child, somersault and
And boy, do we sit. Many of us work at a desk or bench, where our
backs hardly move — unless slumping counts — while
we make countless peripheral motions like pipetting, typing and
using a mouse. Job-associated travel also requires sitting, often
in cramped quarters.
Then — a twinge. Our wrists ache; our elbows burn; our
backs go from feeling pokey to downright sore.
Enter ergonomics, the discipline of adjusting the environment
to fit the human in it.
|Dr. Mark A. Vettraino shows his own cervical
X-rays during a class on ergonomics, the discipline of adjusting
the environment to fit the human in it.
"You don't have to work in pain," says Nerhosshia Davis-Smith,
ergonomics program manager with the Division of Occupational Health
and Safety (DOHS), Office of Research Services. "We want people
to know we are here."
Sixty-four percent of recorded injuries/illness es at NIH's Occupational
Medical Service (OMS) in 2005 involved some form of repetitive
stress injury (RSI). Caused by incorrect posture and/or uninterrupted
repeated motions, RSIs are musculoskeletal disorders that include
carpal tunnel syndrome, "tennis elbow" and "trigger finger" in
which soft tissues — such as muscles, nerves, tendons and
ligaments — are injured.
The physical stress in factory settings may be obvious; it's not
as obvious in the lab and office, so education is crucial. Also
known as repetitive motion disorder and cumulative trauma disorder,
RSIs are preventable and treatable.
DOHS conducts at least 40 ergonomic evaluations each month at
NIH, Davis-Smith reports. In 2001, according to the Bureau of Labor
Statistics, non-fatal occupational injuries across the U.S. topped
1.5 million; over one-third were musculoskeletal disorders (i.e.,
RSI). The costs are enormous.
In response, DOHS is offering its Ergonomic Lecture Series, which
kicked off June 7 with "The Body vs. the Office," by Dr. Mark A.
Vettraino, a specialist in ergonomics and human factor design,
covered basic principles of anatomy and physiology "to show," he
said, "how the body wears out, and why, so you can assess your
He focused on the spine, pointing to 60-degree arcs in each of
its normal curves (neck, mid-back and low-back). "So it's physically
impossible to sit at 90 degrees," he explained, "although you're
told to. Then you get sore between the shoulder blades from the
weight of supporting that 12-pound bowling ball" — also known as
your head. Better to lean back slightly, he suggested, from 91
to 112 degrees.
In a brief case history, he showed X-ray slides of a cervical
(neck) spine with osteoarthritic changes. The cause? Neither the
patient's diet nor his job had changed. But his computers had — from
a desktop to a laptop. Sitting long and leaning forward had put
too much force on the neck; repeated stress caused not only soft
tissue inflammation, but also changes to the bones. Solution: To
better align head, neck and computer, prop the laptop on a 3-ring
binder. You can reverse such joint disease, Vettraino said, as
long as the degenerative changes are structural, not physiological.
"At age 10," he explained, "you begin to lose direct blood supply
to the discs [the pulpy cushions between spinal vertebrae]. The
only way the disc absorbs nutrition is through motion, when it
uses osmosis. Sitting causes changes in the disc matrix, which
settles from a semi-liquid jelly to a semi-solid clay." The body
transmits that wear and tear on the soft tissue to the bone.
"If it doesn't move, it fuses," he stressed.
The patient outcome? "This is an X-ray of my own neck," he said, "and
now I have to practice what I preach."
- DO yoga — probably the best exercise for the spine.
- DO stretch every 30 to 45 minutes.
- DO keep keyboard and mouse in your "primary" zone, within elbow's
reach, no further away than the knees, with mouse on the same
platform as keyboard.
- DO seek your own comfort level when adjusting the monitor.
The eyes have a natural sweep of 30 degrees, so the rule of thumb
is to keep the roof of the mouth parallel to the ground.
- DO keep wrist and forearm straight, in neutral position.
And DO keep knees at an angle, from 0 to 3 degrees, either above
or below hip joint. Why the range? Because one out of five folks
has some abnormality in his or her lower back, he explained. "We're
not all textbook-normal. This depends on the individual. So we
give them that range because unless we do an exam, we can't identify
who they are. That's why I say take these as guidelines and seek
your own comfort level."
The medical profession needs to get more involved with ergonomics,
he noted, and ergonomics needs to catch up to the medical field.
His lecture was an inspiring point where the two could meet.
For a schedule of remaining talks, visit http://dohs.ors.od.nih.gov/ergo_speaker.htm.
To learn more about the Ergonomics Program at NIH, visit http://dohs.ors.od.nih.gov/ergonomics_home.htm.