Finger dexterity, skin temperature, and blood flow during auxiliary heating in the cold

Human Protection and Performance Group, Defence Research and Development Canada-Toronto, Toronto, Ontario, Canada M3M 3B9 Submitted 21 January 2003 ; accepted in final form 27 April 2003 The primary purpose of the present study was to compare the effectiveness of two forms of hand heating and to discuss specific trends that relate finger dexterity performance to variables such as finger skin temperature (T fing ), finger blood flow ( fing ), forearm skin temperature (T fsk ), forearm muscle temperature (T fmus ), mean weighted body skin temperature ( sk ), and change in body heat content ( Hb). These variables along with rate of body heat storage, toe skin temperature, and change in rectal temperature were measured during direct and indirect hand heating. Direct hand heating involved the use of electrically heated gloves to keep the fingers warm (heated gloves condition), whereas indirect hand heating involved warming the fingers indirectly by actively heating the torso with an electrically heated vest (heated vest condition). Seven men (age 35.6 ± 5.6 yr) were subjected to each method of hand heating while they sat in a chair for 3 h during exposure to -25°C air. fing was significantly ( P < 0.05) higher during the heated vest condition compared with the heated gloves condition (234 ± 28 and 33 ± 4 perfusion units, respectively), despite a similar T fing (which ranged between 28 and 35°C during the 3-h exposure). Despite the difference in fing , there was no significant difference in finger dexterity performance. Therefore, finger dexterity can be maintained with direct hand heating despite a low fing . H b , sk , and T fmus reached a low of -472 ± 18 kJ, 28.5 ± 0.3°C, and 29.8 ± 0.5°C, respectively, during the heated gloves condition, but the values were not low enough to affect finger dexterity. body heat content; heated gloves; indirect vasodilation; body temperature; torso heating Address for reprint requests and other correspondence: D. Brajkovic, Defence Research and Development Canada-Toronto, Human Protection and Performance Group, 1133 Sheppard Ave., West Toronto, Ontario, Canada M3M 3B9 (E-mail: dragan.brajkovic{at}drdc-rddc.gc.ca ).