The sweating foot: local differences in sweat secretion during exercise-induced

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Aviat Space Environ Med. 2006 Oct;77(10):1020-7.

The sweating foot: local differences in sweat secretion during

exercise-induced hyperthermia.

NA, Caldwell JN, Mekjavic IB.

School of Health Sciences, University of Wollongong, Wollongong,

Australia.

INTRODUCTION: Little is known regarding local differences in foot

sweat secretion. Since such information is important to our

understanding of sweat gland control for thermoregulatory modeling

and for the design of footwear we explored this topic.

METHODS: Local sweat rates were investigated across core

temperatures from 37-39 degrees C, achieved using endogenous

(cycling) and exogenous heat (water-perfusion garment: 46 degrees

C). Six healthy adults (three men, three women) performed one-

legged, incremental cycling in a heated, climate-controlled chamber

(36 degrees C, 60% relative humidity). Sweat rates were measured at

the forehead and stationary (left) foot (capsules 3.16 cm2): three

dorsal sites (base of toes, second metatarsal, and mid point), the

lateral, and the central plantar surfaces.

RESULTS: Terminal core temperatures ranged between 38.3-39.1 oC,

with peak heart rates of 155-187 bpm. Most foot sweat rates were <

50% of that observed at the forehead: dorsal 1 (38%); dorsal 2

(54%); dorsal 3 (37%); lateral (24%); and plantar surfaces (18%).

When averaged across the trial, local sweat rates were: 2.61

(forehead); 0.98 (dorsal 1); 1.39 (dorsal 2); 0.95 (dorsal 3); 0.62

(lateral); and 0.47 mg cm2 2 min-1 (plantar).

CONCLUSION: Two key observations emerged. First, sweat secretion

from the experimental foot averaged 30 ml x h(-1), peaking in the

last 5 min at 50 ml x h(-1). Second, approximately 70% of the

measured sweat flow emanated from the upper skin surfaces, with only

30% coming from the plantar surface.