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Updated: May 2, 2026
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Kinematic Analysis Using 3D Motion Capture of Drinking Task in People With and Without Upper-extremity Impairments
Published on: March 28, 2018
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Upper extremity kinematic and kinetic adaptations during a fatiguing repetitive task
Jin Qin1, Jia-Hua Lin2, Gert S Faber3
1Department of Work Environment, University of Massachusetts, Lowell, MA 01854, USA; Liberty Mutual Research Institute for Safety, Hopkinton, MA 01748, USA.
Summary
Repetitive work causes muscle fatigue and musculoskeletal disorders. This study found that workers adapt their movements to reduce shoulder strain, with similar strategies across age groups, though older adults showed greater adaptation effort.
Area of Science:
- Biomechanics
- Ergonomics
- Occupational Health
Background:
- Repetitive low-force contractions are prevalent in workplaces.
- These contractions can lead to muscle fatigue and work-related musculoskeletal disorders.
- Understanding motion adaptations is crucial for preventing injuries.
Purpose of the Study:
- To investigate motion adaptations during simulated repetitive light assembly work.
- To examine changes in movement over time and differences between age groups.
- To identify strategies for reducing biomechanical loading on the shoulder.
Main Methods:
- Ten younger and ten older adults performed simulated assembly tasks.
- Upper extremity kinematics were recorded using a motion tracking system.
- Joint angles, scapular elevation, and joint net moments were analyzed.
Main Results:
- Joint angles and torques decreased across task sessions.
- Kinematic variability increased in the shoulder but decreased distally.
- Motion adaptations were sensitive to the task-break schedule.
- Older adults exhibited greater adaptation effort than younger adults.
Conclusions:
- Kinematic and kinetic adaptations help reduce biomechanical loading on a fatigued shoulder.
- Elbow and wrist joint adaptations may compensate for shoulder variability.
- Motion strategies for muscle fatigue are similar across age groups, with older adults showing more pronounced responses.
