Excessive force is sometimes an issue even if you're not moving your fingers. Holding them rigidly in anticipation of the next tap when you're taking notes on a tablet or zapping enemies in a game on your smartphone requires so-called isometric tension, which puts stress on muscles and tendons. To appreciate the effect, let your arm hang loosely at your side, with your fingers curved naturally. Now, force your finger to maintain the same position by tightening your muscles and joints. Feel the difference? As with larger muscles, the more relaxed you are, the better.
Avoiding eyestrain when using mobile devices. It seems intuitive that the more your eyes have to work to see what's on your touchscreen device, the more likely they'll suffer -- just like reading a book in dim light for hours can lead to headaches, eye pain, and other conditions. Although the physical mechanisms behind many of these conditions are surprisingly obscure, the symptoms are no less real.
In broad terms, the risk of eyestrain and similar problems from tablets and smartphones is directly related to three inherent attributes of the display: resolution (the sharpness of the image), contrast (how bright or dark characters and images are compared to the background), and brightness (how much light the display emits). Since the days of dim, low-resolution screens in early PDAs, technology has made substantial strides in all three areas, and sharp, bright displays like the one in Apple's iPhone and Samsung's Galaxy smartphones are thankfully commonplace nowadays.
But newer high-resolution screens pose problems of their own. Because they pack more pixels per square inch, they're capable of displaying ever-smaller fonts. Like the fine print on paper documents, tiny characters can be difficult to read and cause eyestrain, even if you adjust the brightness to a level that's comfortably balanced with the ambient lighting. Smartphones with touchscreens that support multitouch zooming usually let you selectively magnify text that's too small, though that gets tiresome when you're viewing a page on a handheld. Glasses tailored for reading tablet displays may help, especially if your vision has declined because of age (just as many people benefit from wearing "computer glasses" whose prescriptions are tweaked for sustained computer usage).
Environmental factors also play a role in aggravating some visual complaints. Unlike desktop workspaces, where it's usually not too difficult to find a monitor position that avoids glare from lights, mobile devices are often used in situations where the surroundings are constantly changing. As with laptops, the best you can do is to be aware of what's around you and avoid reflections. And because dryness contributes to some symptoms, avoid arid settings or ask an eye care professional to recommend lubricating drops.
Where we stand, where we're going
Health problems from laptops and mobile devices are probably underreported, in part because people don't know about the risks and may attribute symptoms to other causes. In the 1990s, heightened alertness to computer-related disorders led to a flood of complaints and spawned an industry devoted to helping suffering desktop computer users.
Although it's unlikely that we'll see a similar response to health problems caused by mobile devices, vendors are working on solutions like onscreen keyboards with tactile feedback. Eventually, we may even see smarter devices that alert us when we're using them unsafely. Until then, it pays to be aware of the hazards and take sensible precautions.
This story, "The hidden danger of touchscreens," was originally published at InfoWorld.com. Follow the latest developments in Microsoft Windows and mobile technolgoy at InfoWorld.com. For the latest developments in business technology news, follow InfoWorld.com on Twitter.