Subject wearing motion sensors and VR headset

Better design can stop virtual reality causing real injury

Image credit: Jay Kim

Researchers from Oregon State University (OSU) have been investigating ways in which users of virtual reality (VR) headsets could fully benefit from the activity without causing physical risk to participants.

The study assessed how some common VR movements contribute to muscle strain and discomfort, with the team hoping the alternative gestures they suggest will ensure future user safety of this fast-growing technology that is used not only for gaming but also increasingly for education and industrial training.

“There are no standards and guidelines for virtual and augmented reality interactions,” said researcher Jay Kim of OSU’S College of Public Health and Human Sciences. “We wanted to evaluate the effects of the target distances, locations and sizes so we can better design these interfaces to reduce the risk for potential musculoskeletal injuries.”

VR users wear a headset and engage in full-body, three-dimensional movements – this compares to conventional computer users, where a desk or the arms of a chair offer some level of support for the hands and arms.

As part of the study, sensors were placed on participants’ joints and muscles, and the team used motion capture to record their movements and electromyography to measure electrical activity in their muscles while performing common VR gestures. Wearing an Oculus Rift VR headset, the participants were either pointing to specific dots around a circle or colouring in a certain area with their finger.

The researchers repeated the tests with the visuals placed at eye level, 15 degrees above eye level, 15 degrees below eye level and 30 degrees below eye level.

Motion capture and electromyography sensors measure the study participant’s movement and muscle activity while performing common VR movements.

Motion capture and electromyography sensors measured the study participant’s movement and muscle activity while performing common VR movements

Image credit: Oregon State University

Kim found that regardless of the angle, extending the arm straight out causes shoulder discomfort in as little as three minutes. And with prolonged use, as VR often requires, this may lead to major health problems such as 'gorilla arm syndrome' and rotator cuff injuries.

Furthermore, Kim said the heavy VR headset may increase the burden on the cervical spine, risking greater neck strain.

In computer users, the relationship between awkward postures or repeated movements and musculoskeletal disorders is well known. “We wanted to see how the VR compares to conventional computer-human interactions,” Kim said.

The aim of the study was to establish a baseline of optimal object placement and angles. This is to ensure VR developers going forward can design games and programs that minimise user discomfort.

Researchers focused on neck and shoulder movements and found the performance in the colouring task was worst when the participants had to tilt their heads down 15 and 30 degrees.

The most extreme postures and highest muscle activity were observed with targets at 15 degrees above eye level, as participants were forced to constantly maintain their extended neck and elevated arm position. The discomfort was greatest in the pointing task at 15 degrees above eye level, the team said.

“Based on this study, we recommend that objects that are being interacted with more often should be closer to the body,” Kim suggested. “And objects should be located at eye level, rather than up and down.”

The findings could have a massive impact, given VR’s growing demand, according to the team, with tech analysts projecting that roughly 168 million people worldwide will have some form of VR installed by 2023.

A major portion of users are gamers; however, VR’s practical applications have extended to other sectors such as healthcare, the military, education and training. In coal mining, for example, trainees use VR to practise new skills that would be dangerous to learn on-site.

Kim’s main goal is to avoid the mistakes of the past. When personal computing was first emerging in the 1980s and ’90s, he said, people often didn’t think of the risks of overuse until it was too late. With VR, he said, “We’d like to learn now rather than later.”

In November 2019, researchers from Imperial College London announced details of a VR experience with Arctic scenes that could help people suffering from chronic pain.

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