Eccrine sweat glands are most numerous on the soles and palms and then, in decreasing order, on the head, trunk and extremities. The sweat concentration of sodium is genetically determined, and can be considerably decreased with physical training. As an athlete becomes heat acclimatized, the sodium concentration of sweat decreases, sweating begins earlier in exercise, and sweating is more copious. In other words, the athlete may lose as much as 6.6 pounds per hour via sweating while being able to replace only 2.2 pounds per hour by absorbing fluids. Athletic events associated with high sweat rates for several hours guarantee player dehydration.
Sweat literally becomes the water of life.
For sweat to have its beneficial cooling effect, it must evaporate. For each liter of sweat which evaporates, the athlete loses 580 Kcal of heat. The sweat which dramatically drips to the ground at the feet of the athlete is water wasted. Wiping sweat from the face and hands provides comfort and a better grip, but little cooling. The athlete's sweat-drenched shirt offers mute testimony to the ineffectiveness of his sweating.