Mobile technology couldn’t have even been imagined in the smoke and booze-filled “Mad Men” days, and in the office environment, ergonomics wasn’t exactly a priority. The chairs were hard and typewriters stationary; maybe the afternoon cocktail numbed any wrist pain from the repetitive use of this “device.”
As the typewriter evolved into the desktop and wrists were completely wrecked, ergonomics became a buzz word and repetitive motion injuries (RMI) a problem.
In fact, according to the Bureau of Labor Statistics, 10 years ago carpal tunnel syndrome accounted for a median of 27 days out of work. Today RMI still account for a large percentage of workman’s comp claims and mobile technology has brought a whole new world of constant motion.
OSHA has an ergonomic evaluation checklist
based on a desktop environment whose No. 1 suggestion is that the head and neck be to be upright, or in-line with the torso (not bent down/back). and facing forward. Going down the list, the trunk should be perpendicular to the floor, shoulders and upper arms in line with torso; forearms, wrists and hand straight and in line (forearm at 90 degrees); wrists and hands straight, thighs parallel to the floor; lower legs perpendicular; and feet flat.
Ok. Now try that with a tablet. It’s hardly feasible.
The old guidelines don’t much apply to the mobile worker of today, and the ergonomics of mobile technology, tablets in particular, is obviously in its infancy as the devices themselves are fairly new. Still, there is already research pointing to the long-term effects of hunching, scrunching, swiping, squinting and other repetitive habits that go along with tablet use.
A combination of researchers from the Department of Environmental Health, Harvard School of Public Health, Microsoft Corporation, the Department of Orthopedic Surgery, Brigham and Woman’s Hospital and Harvard Medical School, in their paper, “Touch-screen tablet user configurations and
case-supported tilt affect head and neck flexion angles.” concluded, “The use of media tablet computers is associated with high head and neck flexion postures, especially compared to those for typical desktop computing scenarios.”
Flexibility and Strain
Dr. Jack Dennerlein, Harvard Medical School, one of the paper’s authors, broke it down simply in an email to Mobile Enterprise: “The good news is that mobile technology allows us to take on many different postures. The issue is that many of these postures put physical strain on our bodies. For short periods of time these strains are not a huge problem; however, users often let the technology engage them for long periods of time so the interaction of strain and duration increases risk for pain and injury.”
Interestingly, part of the reason it’s a challenge to study the way people position themselves while using tablets, is what also makes them so appealing to use — their “high portability.”
Since there are no design or usage guidelines like those cited earlier for desktop environments, the authors say, “Hence, there is an imminent need for evaluation of tablets while in their early stage of acceptance in order to build a set of recommended guidelines to optimize system performance and users’ well-being.”
There are so many potential display positions and locations during the use of a tablet. The authors note that past studies of computer work have investigated how display/monitor positioning affects neck and shoulder posture and muscle activity.
Higher display locations lead to decreased flexion that approach with more neutral, and recommended, postures; but facing down leads to increasingly flexed postures. “Biomechanical models of the neck musculature show that excessive head flexion leads to large muscle loads and strain. As a result, it is generally hypothesized that very low monitor positions may put users at risk of developing neck and shoulder discomfort or musculoskeletal disorders.”
With most mobile device users typically running around heads down in their phones, it’s easy to assume a similar bad behavior when it comes to tablets. In order to try and represent typical user situations, researchers placed the participants in several positions.
Task, Configurations, Type
The tasks performed included Internet browsing and reading, game playing, email reading and responding, and movie watching. These were done while seated in a lounge type chair and with an ottoman-style footrest as an available option. “The goal was to have the subject sit in a comfortable position that would be similar to how they would use their own tablet at home or travelling,” stated the report.
They used an iPad 2 and a Motorola Xoom. Each was held landscape and had a propriety case (Smart Cover and Portfolio Case) that could be adjusted to prop or tilt the device. “Four user configurations, which consisted generally
of a location (on the lap or table) and a support condition (handheld or in a case), were tested.” The four configurations were tablet held on lap, tablet in case on lap, tablet on table in case and tablet in case propped at a higher angle.
“Overall, the observed head and neck flexion angles are far from
neutral angles,” said the report. “Only for the ‘Table-Movie’ configuration, where the device was set in its steepest case angle setting and at the greatest horizontal and vertical position, did posture approach neutral.
Notably, the differences in head and neck angles were likely driven by differences in case design, “which drastically altered the tablet tilt angle and corresponding viewing angle.”
Essentially, according to the report, “Results suggest that continuous use of tablets for longer durations should incorporate placement of the device on higher surfaces and with steeper case angle settings.”
Mobile Enterprise asked Dennerlein what he suggests. “Keep moving!” he replied. “Don't get stuck in any one position for too long. The other thing is to go ‘hands free’ — get a good stable case that allows for multiple viewing angles. This frees up your hands and arms to do other things and to keep them moving. Having multiple viewing angles allows for better head neck postures.”
Hands free with a case or viewing angle is one thing, but as the research points out, “steeper tilt angles may be detrimental for continuous input with the hands.” In other words, how do you work on a tablet hands free?
The report itself often acknowledges that this research is preliminary and the authors concluded that “further studies examining the effects of tablet and configuration on arm and wrist postures are needed to clarify and complete the postural evaluation.”
Indeed, when asked about the long-term effects, Dennerlein said, “We don't know, really. What we fear is that the reoccurring pain will lead to chronic pain and chronic musculoskeletal disorders. The other issue that we fear is that this technology will lead to more sedentary behavior, which has specific health risks including cardiovascular diseases and metabolic disorders.”
Dennerlein is involved in additional research on this topic and he is not the only one. For example, the Ergonomics Program
, affiliated with the Center for Occupational and Environmental Health, a University of California umbrella organization has ongoing projects as well.
One is on tablet design. The project summary says: “Can the shape and texture of tablets be changed so that they are more secure and comfortable to hold in one hand? We are testing different tablet designs to evaluate their impact on productivity, comfort, and biomechanics. In the first study, 30 experienced users tested eight tablet prototypes while forearm electromyography, upper body posture, productivity and usability were evaluated. The study findings will be useful for designers of tablets and smart phones.”
Dr. David Rempel, Director, Ergonomics Program, University of California, Berkeley confirmed that, “The study is done and we have submitted a manuscript it to the journal Ergonomics.”
Stanford University has already come up with an “Ergonomics Guidance for Mobile Devices”
When it comes to tablets, they too suggest to concentrate on neutral, non-flexion position. “Sync the tablet with a compaitble computer montior or television to improve neck pstures and increase screen size. Place the tablet keyboard in a position that allows the shoulders to relax and elbows to rest at the sides.”
The University of Arizona has also delved into the topic. Its report on “The Impact of Musculoskeletal System during Mutlitouch Tablet Interaction
s shows similar findings and notes that device positioning can introduce stress to the body. The study concluded: “Poor design strategies can cause biomechanical and physical stress to the musculoskeletal system and are associated with work-related musculoskeletal disorders.”
In addition, The Portland State University senior capstone team, working with Intel, created a robotic tablet charging device for individuals with limited mobility. The prototype, completed in 2012, is designed to transport a tablet to a charging station, so that users who are unable to reach a wall outlet due to ergonomics can have access. The device is able to travel more than 40 ft wirelessly, turn 360 degrees and operate on multiple surfaces.
What are you reading this on right now? Are you sitting up straight?