Original Research Article
Year: 2023 | Month: July | Volume: 13 | Issue: 7 | Pages: 290-306
DOI: https://doi.org/10.52403/ijhsr.20230741
A Predictive Model to Quantify Joint Torques and Support Reaction Forces When Using a Smartphone While Sitting with and Without Support: Toward a Risk Scale Proposition to Prevent Musculoskeletal Disorders
JACQUIER-BRET Julien1,2, GORCE Philippe1,2, MERBAH Johan3
1International Institute of Biomechanics and Surgical Ergonomics,
2Université de Toulon, CS60584, 83041 TOULON CEDEX 9, France
3Association Er Bio-Connect – CS 10121, 83418 HYERES CEDEX, France
Corresponding Author: Julien Jacquier-Bret
ABSTRACT
New portable technologies such as smartphones are developing in a very important way and their use rate is increasing every year. Faced with this growth, it is relevant to consider the risks of developing musculoskeletal disorders related to their increasing utilization. The objective of this study was twofold: 1) to propose a predictive model of the upper body joint angles, torques and reaction forces during smartphone interaction in seated position based on subject’s anthropometric data, environmental conditions and interaction strategies in the sagittal plane; 2) to propose risk scales for joint torques provided by the model and which could be integrated with information on posture as part of the musculoskeletal disorders prevention. One of the original aspects of the predictive model was to consider postural strategies between the trunk and the neck during smartphone interaction. The validation was carried out by comparing experimental data collected from 12 subjects who had to perform texting and web browsing task while sitting on a chair with or without support and the data simulated by the model under the same conditions. The results showed a satisfactory ability of the model to reproduce the subjects' posture. However, more marked differences were observed for reaction forces and for shoulder and elbow flexion when trunk flexion was significant. A validity domain for each parameter was computed for different seat and support heights according to the subjects' body mass index. From these data, joint torques risk scales have been constructed, to characterize the risks incurred by the users.
Key words: Predictive Model, Musculoskeletal disorders, Risk scale, Sitting, Posture, Torque/Force.