Thermal monitoring of hand stress during keyboard typing

Repetitive tasks such as keyboard typing increase hand and forearm temperature after a certain time due to muscular activity. This activity can be objectively quantified by the measurement of temperature changes over time. In this study changes in both hands were recorded while one hand was typing on a standard keyboard and the other one remained static. The temperatures of hands and forearms were recorded using thermal imaging. The infrared camera was positioned in a vertical static position recording an image once a minute over a period of 15 minutes. The thermograms of the 12 healthy volunteers participating in this study were analysed with the software package CTHERM. Results show that after 5 minutes the temperature of the typing forearm increased by 0.5°C compared to the other one. The hands over the same period of time show a difference of only 0.1°C. After 15 minutes the difference between both forearms was 1.2°C but between both hands only 0.4°C. In order to better assess thermal effects of keyboard stress on hands an additional vascular stress test immediately after the mechanical stress may produce increased discrimination. This investigation also shows that other factors such as handedness, age and Body Mass Index affect temperature changes caused by mechanical stress.