Much lower hand strength values were demonstrated in a study by Kunelius et al. involving Australian auto workers compared to the normalized hand strength data of Mathiowetz et al. Since the research results were similar to earlier investigations involving Australian subjects, the authors suggest that global population differences should be recognized when using international normative strength data.
Other key findings included:
· A negative correlation between hand grip, lateral pinch and palmar pinch strength and years worked on the trim line
· A negative correlation between hand grip, lateral pinch and palmar pinch strength and age
· A positive association between height, weight, hand length, and hand breath and hand grip, lateral pinch and palmar pinch strength
· Despite hand dominance, greater grip strength was seen in the right hand.
Volunteers (138 males, 23 females) were recruited from the trim line of a Ford Motor Company plant in Australia. Demographic data was collected involving age, gender, hand dominance, number of years worked on the trim line, and whether it was their usual work area. If the employee was on restricted duty as a result of an upper extremity injury, the employee was eliminated from the study.
Height, weight, hand length and hand breadth anthropometric data was measured. Following standard procedures set by Mathiowetz et al., grip strength was assessed using a Jamar dynamometer. Lateral and palmar pinch grips were evaluated according to standard methodology while using a B and L Engineering pinch gauge. Three trials were taken of each hand strength measurement with the mean value assigned to the subject.
The mean strength (kg) of right hand dominant subjects was:
· Right grip – 40.18
· Left grip – 36.79
· Right lateral pinch – 9.33
· Left lateral pinch – 9.05
· Right palmar pinch – 7.68
· Left palmar pinch – 7.47
The mean strength (kg) of left hand dominant subjects was:
· Right grip – 31.75
· Left grip – 29.63
· Right lateral pinch – 7.89
· Left lateral pinch – 7.57
· Right palmar pinch – 6.80
· Left palmar pinch – 6.65
Those less than the mean age (38.5 years) had significantly stronger right sided grip and right sided palmar pinch strength then their older cohorts but no difference in lateral pinch strength. For all age groups, the right hand exhibited greater grip strength. Those younger than the mean age demonstrated greater lateral and palmar pinch strength with the right and compared to the left. Those older than the mean age demonstrated no difference between hands regarding lateral and palmar pinch strength.
There was no difference in grip, lateral pinch, or palmar pinch strength between subjects with little job experience (less than 5 months) and subjects considered very experienced (greater than 20 years on the job).
Author identified reservations effecting the interpretation of this research were:
· English was a second language for many volunteers; there may have been some communication confusion that influenced behavior
· Subjects with large fingers experienced some discomfort when generating palmar pinch force on the gauge due to a pointed edge; this could have effected their force values.
Article Title: Development of normative data for hand strength and anthropometric dimensions in a population of automotive workers
Publication: Work 28: 267-278, 2007
Authors: A Kunelius, S Darzins, J Cromie and J Oakman
This article originally appeared in The Ergonomics Report™ on 2007-06-06.