Use of tablet computers can place strain on the muscles that support the head and neck. A study has investigated which positions put the greatest strain on the neck, to determine best ergonomic use of a tablet computer.
The use of tablet computers has increased dramatically, especially in the younger demographic. As of 2014 an estimated 42% of people over the age of 18 own a tablet computer. The risk of neck pain is substantially increased with the use of tablet computers, and a recent study has evaluated the biomechanics of the head and neck while using a tablet computer. The study calculated gravitational demand, defined as “the ratio of gravitational moment due to the weight of the head to maximal muscle moment capacity”. Gravitational demand was calculated for various postures and working conditions including: with or without a desk, with or without an accessory, while reading, or during typing tasks.
Thirty three people took part in the study, and were split into two separate groups; one for reading, and one for typing tasks. Once participants had completed their 2-5 minute task, both photos and radiographs were taken to assess their posture. The study reported a gravitational demand up to 5 times higher than seen with neutral posture when using a tablet computer. This gravitational demand was reduced if the tablet was in a high propped position. When using the tablet in the flat position, the gravitational demand was greater than when using it propped up. Similarly, when using the tablet in the lap, the gravitational demand was higher compared with having it propped up in a low position, or flat on the desk. When participants were allowed to choose their own posture, there was not a significant reduction in gravitational demand.
Overall, the study found that gravitational demand varies depending on display heights. In positions of higher gravitational demand the neck flexion is also greater, and this has been correlated with neck pain.
A better understanding of the biomechanics involved in tablet use will provide information from which to develop ergonomic recommendations, such as those currently available for desktop computer display height and keyboard placement. The results of the current study suggest that the best positions to be using a tablet are on a desk, in the high propped position, either with or without accessories. However, after surveying the participants, the authors found that the majority of people used their tablet in their lap. This is the position that places the greatest gravitational demand on the head and neck.
The results of the study suggest that it may be beneficial to try using it in the propped up position on a table or desk, to reduce the gravitational demand placed on your head and neck.
Vasavada, AN, Nevins, DD, Monda, SM, Hughes E, Lin DC. “Gravitational demand on the neck musculature during tablet computer use” Ergonomics Published online: 02 Feb 2015.
Image courtesy of bplanet at FreeDigitalPhotos.net
Written by Deborah Tallarigo, PhD