When Using an iPad, How Low Should You Go?

The lower you hold your iPad, the more likely you are to experience shoulder and neck pain, a study shows.

We’re used to staring at computer and laptop screens, so it’s easy to think that using the iPad and other touch-screen devices is a no-brainer. But according to a team of researchers from Harvard School of Public Health, Microsoft and Brigham and Women’s Hospital, the use of media tablet computers is associated with high head and neck flexion postures, leading to muscular stress and pain.

People who use tablets tend to use them in positions that could mean “more of a concern for the development of neck and shoulder discomfort,” said Jack T. Dennerlein of Harvard and the study’s lead investigator. The study is “Touch-Screen Tablet User Configurations and Case-Supported Tilt Affect Head and Neck Flexion Angles.”

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One significant difference between tablet and desktop or notebook computers is that a tablet’s touch screen integrates display and user input. Instead of just looking at the screen, the user touches it, and generally does so from varied positions—and the sudden popularity of the device means no one has really assessed the best ways to use it ergonomically, the researchers noted.

The inherently flexible, portable nature of the touch-screen tablet makes it easy to use in ways that can cause neck and shoulder pain. Lying on the couch, sitting propped up in bed, at a table—using a tablet in nearly any position can be at the whim of the user.

 

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Because computer work has been and continues to be associated with neck and shoulder pain, many studies have examined how the positioning of the display or monitor affects neck and shoulder posture and muscle activity. Studies have shown that the higher the display, the lower the incidence of head and neck flexion. When a device’s display is lower down, the vantage point led to a higher degree of flexed postures, and an associated increase in neck and shoulder activity and pain. As a result, using a monitor in a very low position could be a factor in neck and shoulder pain.

The purpose of the study was to investigate head and neck posture for various positions common in typical tablet computer use, and how head and neck posture varies with different tablets and their case designs, with different tilt angle settings.

Fifteen experienced tablet users completed a set of simulated tasks with two media tablets, an Apple iPad2 and a Motorola XOOM. Each tablet had a proprietary case that could be adjusted to prop up or tilt the tablet computer. The Apple Smart Cover allows for tilt angles of 15° and 73°, and the Motorola Portfolio Case allows for tilt angles of 45° and 63°. Four user configurations were tested: Lap-Hand, where the tablet was placed on the lap; Lap-Case, with the tablet placed on the lap in its case set at the lower angle setting; Table-Case, with the tablet placed on a table with its case at the lower angle; and Table-Movie, with the tablet placed on a table with its case at the higher angle.

During the experiment, users completed simple computer tasks such as Internet browsing and reading, game playing, e-mail reading and responding and movie watching. Head and neck postures and gaze angle and distance were measured using an infrared three-dimensional motion analysis system.

 

 

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Head and neck flexion varied significantly across the four configurations and across the two tablets tested. The iPad2 was associated with more flexed postures when it was placed in its case. This appeared to be driven by differences in case design, which drastically altered the tablet tilt angle and the corresponding viewing angle. For both tablets, the gaze angle changed in a similar fashion to the head flexion across all configurations, with nonperpendicular viewing angles causing increased head and neck flexion. Head and neck flexion angles were greater, in general, than reported for desktop or notebook computing.

Only when the tablets were used in the Table-Movie configuration, where devices were set at their steepest case angle and at the greatest horizontal and vertical position, did user’s posture approach neutral. This suggests that tablet users should place the tablet higher, on a table rather than a lap, to avoid low gaze angles, and use a case that provides steeper viewing angles. But the suggestion comes with a caveat: Steeper angles may be detrimental for continuous input with the hands.

Further studies on the effects of tablet and configuration on arm and wrist postures are needed, Dennerlein said. He noted that the results will be useful in updating ergonomic computing standards and guidelines for tablet computers, which “are urgently needed as companies and health care providers weigh options to implement wide-scale adoption of tablet computers for business operations."

The study is available here.

 

Russell and Barclays Launch LDI Index Series

Russell Investments and Barclays launched a set of investable liability-driven investment (LDI) fixed-income benchmarks for U.S. corporate pension funds. 

The Barclays-Russell LDI Index Series combines the capabilities of the two organizations to offer pension fund investors a standard set of rules-based and transparent fixed-income benchmarks that are designed to offer better liability tracking properties than traditional benchmarks currently in use.

“In speaking with clients through LDI consulting and asset management conversations, it became clear that plan sponsors needed a way to more accurately hedge their liabilities, but they also still wanted a transparent and investable index set to benchmark their fixed-income managers against. Currently available fixed-income index products were not fully addressing those needs,” said Martin Jaugietis, CFA and director of LDI Solutions at Russell Investments. “By collaborating with a leading fixed-income index provider like Barclays, we are able to fill this gap.”

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The Barclays-Russell LDI Index Series is available for a wide range of investors, including defined benefit pension plans, dedicated fixed-income asset managers looking to broaden their LDI product suite and plan sponsors with more than half of total pension assets in LDI fixed income that want a more appropriate measure of liability returns.

The Series consists of six high quality, mostly corporate-bond-based, benchmarks with target durations of 6, 8, 10, 12, 14 and 16 years. Each LDI index is reconstituted annually back to the targeted maturity minimum range to reflect changes in market yields while minimizing turnover and rebalanced monthly to remove bonds falling below the maturity threshold or quality standard and add newly issued bonds that qualify. Issuer concentration is reduced through a 2% issuer cap. When using the Series, investors will be able to select a single LDI index or a combination to most accurately reflect their specific liabilities.

“By better matching the risk and return characteristics of typical liability streams with a smart cash bond-selection strategy, the Barclays-Russell LDI Index Series is a useful performance target for investment portfolios designed to fund specific liabilities,” said Brian Upbin, head of Benchmark Index Research for Barclays. “This rules-based index series will give asset owners, asset managers and investment managers a new portfolio benchmarking tool.”

 

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