result workers frequently choose to alternate between hand use and various

Result workers frequently choose to alternate between

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result, workers frequently choose to alternate between hand use and various postures to avoid discomfort during sustained and repetitive tasks. Individual anthropometry and strength likely play a role in these choices, although this was not borne out in the current study. The dominant arm has been found to be more susceptible to MSD than the nondominant arm (Shiri,Varonen, Haliovaara, & Viikari-Juntura, 2007), suggest-ing differences in exposure to physical load fac-tors between hands. Force differences between dominant and nondominant hands were only observed in the chuck pinch (Figure 2), where the force generated by the dominant hand (83.2 ± 16.2 N) was greater than the nondominant (75.9 ± 16.2 N) hand. Therefore, it is assumed that hand dexterity may play a greater role in this particular grip type. In addition, the chuck pinch may be used more frequently; thus, skill level may be associated with the type of pinch used and the force generated.Regardless of hand, the thenar pinch was the only pinch grip type that had higher forces in the wide span (106.6 ± 21.2 N). All other pinches had an increase in force in the narrow span with the two-handed pinch having the highest force Figure 2.Mean maximal pinch grip force (N) with standard deviation for all postures. (A) Three pinch grip types using both dominant and nondominant hands as well as narrow and wide grip spans. (B) Two-handed pinch using narrow and wide grip spans. The * designates this grip was significantly different (p< .05) from the thenar and chuck variation pinches in its respective grip and hand dominance condition. The + indicates there was only a statistically significant difference between the respective condition and the thenar pinch (no significant difference between chuck and chuck variation pinch). The two-handed pinch was not included in the ANOVA but is shown for comparison.
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GRIPTYPEINSYRINGEUSE1093(112.1 ± 18.6 N). This could suggest that the the-nar pinch may be best to use when the syringe is mostly full or at the start of a treatment and that use of the two-handed pinch would be best once the syringe is nearly empty or at the end of the treatment. This strategy may promote a lower relative effort throughout the push and decrease the risk of fatigue and consequently, injury.A note of caution arises with repeated use of the thenar pinch. This pinch involves compres-sion on the thenar eminence and thus the recum-bent branch of the median nerve, which may increase the risk of injury to the surrounding tissues. Often, the choice of pinch grip used in the field is influenced by the object gripped and the task performed (Imrhan & Sundararajan, 1992), in this instance, a syringe. As a result, the two-handed pinch may be the best option since it produces greater force while avoiding the com-pression of important nerve structures. However, as suggested in tool design, increasing the size of the contact surface area, placing padding on the contact surface, and limiting total exposure time may avoid such point compression of this area and allow the thenar pinch to be beneficial for
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  • Fall '07
  • Statistical significance, Median nerve, Hand strength, pinch grip

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