Sweating on paws and palms: what is its function?

Man sweats on his palms and the soles of his feet in response to stress and exercise, but not in response to heat. Several functions have been proposed for this type of sweating: increasing friction between skin and substrate; increasing the toughness of the skin; and increasing tactile sensitivity. This study uses a comparative approach to evaluate the role of footpad sweating on increasing friction, utilizing a variety of mammals which possess sweat glands on their footpads (rat, tenrec, hyrax, and dog). We found that all of these animals sweat on their paws while running. Blocking this sweating with atropine sulfate dramatically decreased the coefficient of static friction between the paw and the tread of an inclined treadmill. A similar dose of atropine sulfate had no effect on the coefficient of static friction in a rabbit, and animal that possesses no sweat glands on its paws. We conclude that an important function of this type of sweating is to help prevent slipping between the paw and sthe substrate during running or climbing, and we postulate that the sweating observed in response to stress may play an important role in preparing an animal for fleeing from stressful situations.