Ulnar deviation and short-term strength reductions as affected by a curve-handled ripping hammer and a conventional claw hammer

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Abstract
Sixteen volunteers were engaged to study the influence of a curve handled ripping hammer (E) and a conventional claw hammer (C) on ulnar deviation and strength decrement during similar work tasks. The subjects were asked to drive 20 pre-started box nails, 8-9 cm in length, into a stabilized board with the striking rate paced at 72 beats min−1Bilateral grip strength was determined by the use of a, calibrated force monitor before and after the assigned work task. A repeated measures design was used with the order of E and C determined randomly. In addition, cinematographic procedures were used to determine ulnar deviation using a professional carpenter as the subject. It was found that E affected a strength decrement for peak and average values that was 52 and 42% less, respectively, for E in comparison to C. Ulnar deviation was found to be 2-6 times greater for C. It was concluded that the design of E is advantageous with respect to work efficiency and the occupational health of the worker