Association between objective and subjective measurements of comfort and discomfort in hand tools

In the current study, the relationship between objective measurements and subjective experienced comfort and discomfort in using handsaws was examined. Twelve carpenters evaluated five different handsaws. Objective measures of contact pressure (average pressure, pressure area and pressure-time (P-t) integral) in static and dynamic conditions, muscle activity (electromyography) of five muscles of the upper extremity, and productivity were obtained during a sawing task. Subjective comfort and discomfort were assessed using the comfort questionnaire for hand tools and a scale for local perceived discomfort (LPD). We did not find any relationship between muscle activity and comfort or discomfort. The P-t integral during the static measurement (beta=-0.24, p<0.01) was the best predictor of comfort and the pressure area during static measurement was the best predictor of LPD (beta=0.45, p<0.01). Additionally, productivity was highly correlated to comfort (beta=0.31, p<0.01) and discomfort (beta=-0.49, p<0.01).