Effect of direct and indirect hand heating on hand comfort and finger dexterity during cold exposure

grantor: University of TorontoIn the past, torso heating has been shown to be an effective method of keeping the extremities warm without hampering finger dexterity. This thesis examined the effects of different levels of torso heating (using an electrically heated vest) and body clothing insulation to determine the most effective means by which the extremities (fingers and toes) could be kept comfortable for three hours during exposure to -15°C air while vest heater power was reduced. Finger dexterity was measured using two different tests to determine if finger dexterity could be maintained during torso heating. The results indicate that the extremities can be maintained at a comfortable level (finger and toe skin temperature above 25°C) for three hours, but only when an adequate combination of clothing and heating are provided. The effect of torso heating on bare hand comfort was also examined during exposure to -25°C air while the rate of body heat storage, core temperature, mean body skin temperature, finger temperature, finger blood flow, finger comfort and finger dexterity were measured during direct (using electrically heated gloves) and indirect hand heating (using active torso heating). The results indicate that during direct hand heating, the rate of body heat storage ( S&d2; ) was not a good indicator of extremity temperature over time, whereas during indirect hand heating, ( S&d2; ) was a good indicator of extremity temperature. Overall, indirect hand heating was found to be more effective in preventing a decrease in finger dexterity over time compared to direct hand heating if it is necessary to remove contact gloves to do a task, but both methods were equally effective if contact gloves were worn during the task. It is important to note that the last finding is limited to doing a short (