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Mobile input device type, texting style and screen size influence upper extremity and trapezius muscle activity, and
David M Kietrys1, Michael J Gerg2, Jonathan Dropkin3
1School of Health Related Professions, Rutgers, The State University of New Jersey, 40 E. Laurel Road, Stratford, NJ, USA.
Applied Ergonomics
|May 12, 2015
Summary
Texting with physical keypads increases muscle strain compared to touch screens. Using one thumb also elevates wrist extensor activity, and larger screens may worsen muscle and neck posture, potentially increasing musculoskeletal disorder risk.
Area of Science:
- Ergonomics
- Human-Computer Interaction
- Occupational Health
Background:
- Texting is a prevalent activity among college students.
- Understanding the ergonomic implications of different texting methods is crucial for preventing musculoskeletal disorders (MSDs).
Purpose of the Study:
- To investigate the impact of input device type (physical keypad vs. touch screen), texting style (one-handed vs. two-handed), and screen size on muscle activity and cervical posture.
- To identify potential ergonomic stressors associated with mobile phone texting.
Main Methods:
- College students performed a short texting task using various devices and styles.
- Muscle activity in the upper extremities and trapezius was measured using electromyography.
- Cervical posture was assessed.
- Data were analyzed to compare muscle activity and posture across different conditions.
Main Results:
- Physical keypads elicited greater thumb, finger flexor, and wrist extensor muscle activity than touch screens.
- One-handed texting (using one thumb) resulted in higher wrist extensor activity compared to two-handed texting.
- Larger touch screen sizes correlated with increased finger flexor, wrist extensor, and trapezius muscle activity, and a trend towards greater cervical flexion.
- Participants adopted different postures (e.g., device on lap) with larger screens.
Conclusions:
- The type of input device and texting method significantly influence upper extremity muscle activity and posture.
- Larger screen sizes may introduce additional ergonomic stressors, potentially contributing to musculoskeletal discomfort.
- Further research is needed to establish the direct link between observed texting-related ergonomic stressors and the risk of developing musculoskeletal disorders.
