Heated socks maintain toe temperature but not always skin blood flow as mean skin temperature falls.

INTRODUCTION: This study was conducted to examine whether toe skin blood flow (Q(toe)) could be maintained in subjects exposed to cold air by warming the foot using a heated sock.
METHODS: Four male subjects were exposed to air at 4 degrees C. They wore aramid shirt and trousers, a coverall made from metalized spun bonded polyethylene ("space blanket" fabric), arctic mittens, a 4-ply aramid balaclava, and loose fitting padded boot liners. The subjects rested recumbent on a couch with a pair of heated socks turned on for 120 min and with socks turned off for a further 60 min. Q(toe) was measured using laser Doppler flowmetry. RSULTS: Although the heated socks maintained the skin temperature of the feet above 37 degrees C, Q(toe) was not maintained in two of the four male subjects for the 120 min that the socks were turned on. DISCUSSION: Heated socks cannot be relied on to maintain Q(toe) or to prevent non-freezing cold injuries during prolonged exposure to cold conditions.