Profuse sweating is caused when core body temperature increases significantly during exercise due to metabolic heat production. The brain signals the body to dispel the excess heat through sweat glands to cool the body down. Generally, the fitter someone is, the more efficiently they are able to control their body temperature. Blood is shunted to the skin’s surface more quickly via blood vessels that exude heat away from the body. Fitter people also lose less salt since it is reabsorbed by the body’s cells as it travels from the sweat glands to the skin’s surface. The result: copious amounts of sweating and more rapid cooling to assist in more efficiently controlling and cooling core body temperature.