title: Effects of tool handle dimension and workpiece orientation and size on wrist ulnar/radial torque strength, usability and discomfort in a wrench task.
abstract: The effects of tool handle dimension (three modified designs of wrenches with 30-50 mm diameter cylindrical handles and traditional design with rectangular cross-sectional (5 mm × 25 mm) handle), workpiece orientation (vertical/horizontal) and workpiece size (small/large) as well as user's hand size on wrist ulnar/radial (U/R) torque strength, usability and discomfort, and also the relationship between these variables were evaluated in a maximum torque task using wrenches. The highest and lowest levels of maximal wrist U/R torque strength were recorded for the 30 mm diameter handle and traditional wrench design, respectively. The prototype handle with 30 mm diameter, together with 40 mm diameter handle, was also better than other designs as they received higher usability ratings and caused less discomfort. The mean wrist torque strength exerted on a vertically oriented workpiece (in the sagittal plane) was 23.8% higher than that exerted on a horizontally oriented one (in the transverse plane). The user's hand size had no effect on torque exertions. The wrist torque strength and usability were negatively correlated with hand and finger discomfort ratings. The results are also discussed in terms of their implications for hand tool and workstation configuration in torque tasks involving wrenches.
authors.affiliation: Department of Occupational Health and Ergonomics, Faculty of Health, Tabriz University of Medical Sciences, Tabriz, Iran. Electronic address: dianati@tbzmed.ac.ir.
authors.forename: Iman
authors.initials: I
authors.lastname: Dianat
authors.affiliation: Department of Occupational Health and Ergonomics, Faculty of Health, Tabriz University of Medical Sciences, Tabriz, Iran. Electronic address: srahimi1351@gmail.com.
authors.forename: Soleyman
authors.initials: S
authors.lastname: Rahimi
authors.affiliation: Department of Management, Science and Technology, Amirkabir University of Technology, Tehran, Iran. Electronic address: moeinnedaei@yahoo.com.
authors.forename: Moein
authors.initials: M
authors.lastname: Nedaei
authors.affiliation: Tabriz Health Service Management Research Center, Faculty of Health, Tabriz University of Medical Sciences, Tabriz, Iran. Electronic address: m_asgharl862@yahoo.com.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Asghari Jafarabadi
authors.affiliation: Department of Physiotherapy, Faculty of Rehabilitation, Tabriz University of Medical Sciences, Tabriz, Iran. Electronic address: eterafoskouei@tbzmed.ac.ir.
authors.forename: Ali E
authors.initials: AE
authors.lastname: Oskouei
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003612:Dairying / Q000295:instrumentation*; D004867:Equipment Design; D006804:Ergonomics; D018737:Hand Strength; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology*; D013647:Task Performance and Analysis; D019415:Torque; D014955:Wrist Joint / Q000502:physiology*
keywords: Hand tools; Handle diameter; Spanner wrench; Wrist torque