Study of the response of the area of the palm to impact: Relationship between the physical characteristic of the palm impact and the subject perception of the severity of the palm impact

• This study aimed at measuring subject's perception of severity of impact when using the base of the palm of the hand.
• The subject perception of the severity of impacts to the palm was most affected by the level of the force of the impact.
• The vertical force resulted in higher perceptions of severity.
• Interactions and covariates were statistically significant in some of the models tested.

Even though using the hand as a hammer causes injury, the practice continues, and may be increasing, in industry and in jobs that require intensive manual labor. This was an exploratory study aimed at measuring the relationships between the forces of strikes, the relative angles of strikes, and/or the number of strikes (up to 3) with the perception of severity of strikes when using the base of the palm of the hand. Eight subjects struck a metal force plate with the base of the palm of the hand at three levels of force, three levels of angle with respect to the surface of a force plate, and with three different numbers of times in a trial. Subjects were then asked to give a psychophysical rating after each trial. The subjective perception of the severity of each impact and force-time curves were recorded. From each force-time curve, peak force, maximum acceleration of force application, and the area of the force curve from initiation to peak were determined. Sixteen ANOVA models were analyzed.Results indicated that the subjective perception of the severity of impacts to the palm was most affected by the level of the force of the impact. Other factors, interactions, and covariates were statistically significant in some of the models tested. This study concluded that the vertical force (normal to the palm of the hand) was the determining factor governing the perception of severity of an impact to the palm of the hand.Relevance to industryThis research has an applications in industries where workers use their hands to strike solid objects in order to move them or to attach them to other components.