"Dr. David M. Rempel is an occupational medicine physician at the University of California, San Francisco, and a professor of bioengineering at the University of California, Berkeley. He is also director of the ergonomics research laboratory at the University of California.
Q. Since the late 1980s, there has been much controversy over whether typing on a computer or other repetitive workplace activities could cause repetitive strain injuries of the hand, arm and shoulder. Has that debate been settled?
A. There has been some settling of the issue. It is pretty clear that jobs that involve high-force hand activities and repetitive hand motions — such as in manufacturing or heavy industry or meatpacking — are associated with wrist tendinitis and carpal tunnel syndrome and other arm disorders. Many companies have been making efforts to modify their workplaces to reduce those loads, and they have had some effectiveness in reducing injuries in the workplaces.
But there is still some controversy in the scientific community about whether keyboard and mouse use causes carpal tunnel syndrome.
Q. What is known about carpal tunnel syndrome and computer use?
A. Recent research indicates that the risk of carpal tunnel syndrome, when using the keyboard for less than 20 hours a week, is relatively low or nonexistent. That’s a new finding that has emerged over the past 10 years.
What is still missing is an understanding of what happens when people use the computer keyboard for more than 20 or 30 hours a week for many years. There, the question of carpal tunnel syndrome and keyboard use is still unanswered.
What is also interesting is that in the last few years, strong evidence has emerged that if you use a computer mouse for more than 20 hours a week, your risk of carpal tunnel syndrome is increased. It looks like the mouse may be more problematic than the keyboard, at least for carpal tunnel syndrome. And mouse use is also associated with elbow and shoulder problems.
Q. Many researchers have shifted away from using the term ”repetitive strain injury.” Why is that?
A. Well, the term “repetitive strain injury” has embedded within it the concept that repetition is the cause. But the actual cause may not be repetition per se; it might be prolonged finger loads or static forces or high forces. And so the use of the term has largely been replaced by specific diagnoses that are more exact — carpal tunnel syndrome or wrist tendinitis. Or researchers use a more generic term like musculoskeletal disorder.
Q. Why is it that some people develop these musculoskeletal illnesses when friends or colleagues who are doing exactly the same activities do not?
A. That’s a great question. It may have to do with a difference in their workload. Some people may have a higher hand workload than others. It may have to do with the way they do their work; they may apply larger forces when performing the same task, or forces for longer durations.
If you look at people who do identical hand activities, there’s a slightly increased risk for women than men. This difference is probably due to the relative lower strength of women than men. There are also differences in hand-intensive activities that they do at home or outside of work.
In addition, there may be some personal factors that put a person more at risk: for example, obesity and medical conditions like diabetes." (Continued via NY Times Health, Ingfei Chen) [Ergonomics Resources]