Журнал эргономики
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Quantitative and Qualitative Evaluation of the Lift-assist Device during Jackhammering Task

Blake Johnson, Wilkistar Otieno and Naira Campbell-Kyureghyan

Background: Jackhammers are commonly used on construction sites, and their general use comes with several injury risks, especially focused on lifting the jackhammer. A Lift-assist (LA) device is available that is aimed at eliminating the risk to the user from lifting. However, to date no scientific study has been conducted to determine if the LA provides any benefits to the user. The goal of this study was to make quantitative comparisons and qualitative assessments of operating a jackhammer with and without a LA.

Methods and findings: Eight experienced jackhammer operators broke a 0.9 × 0.9 m section of concrete with two different weights of jackhammers with and without a lift-assist. Muscle activity of the upper body was reduced (approx. 40%) during the lifting portion of the task when using the LA. The reduction of the muscle activity required to lift the jackhammer also enabled the subjects to retain a better posture throughout the lift. Additionally, grip pressure was reduced in the lifting portion of the task. While the LA reduced the time required to lift the jackhammer, no change in overall task completion time was observed due to large variations in the time effect of the lift-assist among subjects and the relatively minor contribution of lifting time to the total task time. A longer study that allowed subjects to better adapt to the LA might be required to assess potential effects on task efficiency. Overall the subjects perceived the LA to provide a benefit to the user during the jackhammer task, and reduced the physiological stress experienced by the operator during the lifting portion of the task.

Conclusions: These results indicate that use of the LA can potentially translate to a reduction in lifting related injury risks to the operator.