The decades-old prescriptions of office ergonomics sought to minimize musculoskeletal damage to people who were sitting fixedly at their desks for hours at a time. But today's office ergonomics experts increasingly do not see sitting for long periods as a good thing.
Meanwhile, the upsurge of mobile devices would seem to offer a way to alleviate the problem -- but it turns out that such devices come with their own ergonomic baggage.
"For decades, ergonomics was billed as a way to get people to stay at their desks longer and more productively," notes Dr. James Levine, director of obesity solutions at the Mayo Clinic, in Rochester, N.Y. and Phoenix. "Over the past six or seven years we have realised the consequences of people sitting too long, and it is an astonishing list."
Specifically, he lists (in no particular order) diabetes, low productivity, hypertension, apathy, clinical depression, hyperlipidemia (elevated levels of lipids in the blood), low moods or mild depression, cardiovascular diseases, obesity, back problems, deep vein thrombosis and mental sluggishness.
"Modern thinking is that we need to reverse the process of 40 years and get people out of their chairs and off their bottoms," Levine says. "Office productivity and school grades improve as people get mobile, as they get up and move. They will tell you that they feel brighter and sharper. They will say, much as I hate the term, 'I feel more alive.' About 10 years ago I had senior scientific colleagues screaming at me in lecture halls about this, saying I was wrong, but now there is international recognition that sedentaryness is killing people."
Mobile's new ergonomics
Oddly enough, no one is saying that mobile devices hold the answer with their potential for personal mobility. This may be because, as it turns out, the mobile gadgets introduce new ergonomic problems.
Tablets, for instance, might at first glance seem to free people from their desks, but in fact people tend to place them flat on their desks and read them as if they were books, explains Dr. Alan Hedge, director of the Human Factors and Ergonomics Laboratory at Cornell University in Ithaca, N.Y. With a book, people will occasionally change posture as they turn the page, but with tablets they can remain hunched for long periods, he notes.
"Leaning forward doubles the compressive forces on the vertebrae in your lower back compared to leaning back," explains Hedge. "When leaning back 20 degrees in a lounge chair you are really relaxing and halving the compression. That is why we say 'sit back and relax,' not 'hunch forward and relax.' "
One result of hunching is a syndrome called iPad Neck -- chronic soreness of the back of the neck and upper shoulders. Hedge recommends propping up the tablet or putting it on a holder so you can read it with a straight neck.
Overuse of tablets may also interfere with getting a good night's sleep, says Dr. Mariana Figueiro, director of the Light and Health Program of the Lighting Research Center at the Rensselaer Polytechnic Institute in Troy, N.Y. Exposure to bright light in the evening will suppress the body's production of the sleep-aid chemical melatonin, making it harder to go to sleep.
The use of an iPad at full brightness for two hours is enough to trigger melatonin suppression, she has found. (She also tried the experiment with TVs and CRT computer screens, but did not find any suppression, presumably because they are less bright and used at greater distances from the eye.)
Some old-school ergonomics still apply
You've probably heard them since the fourth grade, but the admonitions about posture in relation to office ergonomics still hold true.
"As a rule of thumb, you should be able to touch the screen with your fingertips," says Dr. Magdy Akladios, associate professor at the University of Houston-Clear Lake. "The knees, hips and elbows should be at a 90-degree angle. But it's also okay to, for instance, cross your legs -- as long as you don't do it for eight hours straight."
The keyboard should also be flat on the desk. "There is no functional reason for the feet on the back of the keyboard," adds Linda Weitzel, senior ergonomist for Xerox in Rochester, N.Y. (One keyboard maker says the feet serve only to improve visibility for those who can't touch-type.)
Ignoring the rules is as risky as ever. "The complaints have not changed that much since the 1990s," says Weitzel. "The number one problem is back complaints, since they are sitting all day long. Part of it is how effective the computer is today. Whereas five years ago office workers still printed out documents, today they don't even have to get up and go to the printer because they are forwarding documents electronically, or sending links."
In the face of discomfort, act immediately. "The best fix is to stay away from the cause," says Akladios. "You need to prevent the problem motion and introduce a new set of motions, or take frequent breaks. Rather than do any one specific thing, you need to do something different from what you have been doing."
Extensive typing on a tablet opens another can of worms, Hedge warns. "We've done a lot of work on this," he says. First, it slows people down compared to typing on a regular keyboard since it provides no feedback, the varying resistance of a key as it's pressed.
Second, "the fingers tend to get sore since there is no give on that surface. It's like drumming your fingers all day on your desk," Hedge says. "For the convenience of technology we have moved people away from typing and back to poking and prodding, dramatically reducing their productivity. It's ludicrous."
Haptics, which attempt to provide that missing feedback from flat screens, might be a help here -- eventually. But the technologies are still being developed and not yet widely adopted in mobile devices.
Laptops, meanwhile, are considered non-ergonomic by nature, since there is no way to adjust the distance between the keyboard and screen. "Your hands want to be close to your chest, but your eyes want to be focused on something two feet in front of you," making an ergonomic posture unobtainable with a laptop, Hedge explains.
Using laptops on a desk, in place of a desktop, only compounds the problem, he adds. "Desks are usually about 30 inches high, which is a good height for writing by hand on paper but dreadful for typing, as it is too high unless you are taller than 6'2". Then you are adding the height of the laptop."
But he notes that the problem can be alleviated by the use of LCD monitor arms, which hold the laptop in an elevated position where its screen can be used as the system display. An add-on keyboard and mouse can be placed on the desk.