The Effect of Phone Design on Upper Extremity Discomfort and Muscle Fatigue

Objective: To compare a small cellular clamshell phone with a traditional office phone in the development of discomfort and muscle fatigue over time during phone use. Background: Phone use involves low-level static exertions that may be influenced by phone design. Phone design and its interactions w...

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Bibliographic Details
Published in:Human factors 2007-08, Vol.49 (4), p.602-618
Main Authors: Chany, Anne-Marie, Marras, William S., Burr, Deborah L.
Format: Article
Language:English
Subjects:
Adult
Applied physiology
Arm - physiology
Biological and medical sciences
Cellular telephones
Design
Ergonomics
Ergonomics. Work place. Occupational physiology
Fatigue
Female
Hand - physiology
Human factors research
Human performance
Human physiology applied to population studies and life conditions. Human ecophysiology
Humans
Male
Medical sciences
Muscle Fatigue
Muscle pain
Muscles
Musculoskeletal system
Pain Measurement
Space life sciences
Telephone
United States
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Summary:Objective: To compare a small cellular clamshell phone with a traditional office phone in the development of discomfort and muscle fatigue over time during phone use. Background: Phone use involves low-level static exertions that may be influenced by phone design. Phone design and its interactions with anthropometry may change shoulder and hand postures assumed during use, which in turn may modify the length-strength relationship and moment arms of the muscles. Method: Ten adults participated in a study that simulated phone use using a small clamshell and a traditional office phone. Discomfort information and electromyographic (EMG) muscle activity were monitored on four upper extremity muscles. Discomfort and fatigue data (EMG median frequency shifts) were analyzed to assess differences between phones as well as differing effects attributable to anthropometry. Results: Median frequency shifts supported discomfort claims and indicated muscle fatigue in the deltoid and thenar muscles. Biomechanical measures demonstrated that participants with short limb lengths developed more severe signs of thenar fatigue. Participants with longer arms developed greater discomfort in the neck, shoulder, and back. The deltoid confirmed this occurrence, showing signs of muscle fatigue. Conclusion: Phone design and anthropometry influenced the development of discomfort and fatigue during phone use. Phone design dictated grip style, resulting in differing discomfort and fatigue levels. Anthropometry influenced the severity of the discomfort and fatigue present in the shoulder and hand. Application: Use of small clamshell phones may contribute to a lack of rest and recovery from typical workday exposures. It should be explored from an ergonomic perspective.
ISSN:0018-7208
1547-8181
DOI:10.1518/001872007X215683