Abstract
Measurement of thumb force in the industrial filed is important to quantify the risk of manual tasks. However, few studies have assessed the thumb force. Therefore, the purpose of this study was to investigate the relationship between actual thumb force and perceived force according to the force levels and gender. A total of 31 healthy participants (23 males and 8 females) were asked to exert a maximum thumb force (MTF) and random levels of target thumb force (10, 30, 50, 70, and 90% MTF). Results indicated that females exerted approximately 73.6% (100.6 N) of the strength exerted by males (136.7 N). Based on the differences between actual and perceived thumb exertions, the highest accuracy was achieved at 50% MTF, designated as “50%-phenomenon”. At 10% and 30% MTF levels, participants tended to exert greater strength (over-exertion) than the perceived exertions, whereas participants showed less strength (under-exertion) than the perceived exertions at 70% and 90% MTFs. Participants generally exerted greater and lesser thumb force than the perceived exertions at levels lower and higher than 50% MTF, respectively. Thus, the relationship between the actual and perceived force of exertion displayed a nonlinear S-shaped curve.
Highlights
Work-related musculoskeletal disorders (WMSDs) are widespread in professions including construction, mining, manufacturing, and service industry
The results showed significant differences in perceived exertion levels depending on the type of muscle: the RPE (Rating of Perceived Exertion) in the legs was greater than the force of the arm)
The objective of the current study was to investigate the relationship between actual thumb force exertion and perceived thumb force exertion according to the various levels of exertions (10, 30, 50, 70, and 90% maximum thumb force (MTFs)) and genders
Summary
Work-related musculoskeletal disorders (WMSDs) are widespread in professions including construction, mining, manufacturing, and service industry. Rapid repetitive activities and overexertion of thumb (forceful exertions) in physiotherapy, sports, and assembly lines were reported as the leading causes of thumb injuries [3,4] Manual tasks such as initiation of fasteners and insertion of objects are frequently encountered in the automotive assembly industry and are associated with excessive thumb force ranging from 5.1 kgf to 17.0 kgf [5]. This level of exertion may trigger an occupational injury and represent a risk factor for WMSD. Accurate measurement of thumb exertion at work and appropriate interventions, such as personal protective equipment, or modification of facilities according to the degree of thumb
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