Human body has around four million sweat glands and around three million are eccrine sweat glands while the remaining are apocrine sweat glands. Sweat is produced by these glands. Exercise, hot summer days or tense situations cause sweating. Sweating acts as a thermoregulatory function for the body. Sweat on evaporation creates cooling effect. It is assessed that an average adult produce up to a quarter of a gallon of sweat per day. Quantity in children reaches those levels only by puberty.
Eccrine sweat glands are distributed across the body. They are , however, found in great numbers on forehead, palms , cheeks and over soles of feet. They produce an odourless clear fluid that consists of water and salts. Sodium and potassium are major components of the salts. Evaporation of the sweat so produced by eccrine glands does not cause foul smell.
Apocrine glands are mainly found in in the urogenital and axilla region. The colourless fluid produced by these glands contains proteins and fats. Bacteria present in hairy areas like armpits and genital areas of the body break the fluid into products with a characteristic odour. Eccrine glands are present from babies to aged. But, apocrine glands develop and start functioning only around puberty stage. Thus, the sweat produced by the apocrine glands in adults is the cause for the foul smell.
Under certain circumstances, sweat in a child too may carry foul smell. Sometimes the apocrine glands become active due to the presence of prematurely circulating sex hormones. ‘Fish Odour Syndrome’ is a rare genetic condition that leads to formation of trimethylamine, with an offensive fishy smell. Hence, if the sweat of a child causes foul smell despite good personal hygiene, seeking medical advice is a good option.
Genetic factors determine how much a person sweats and howmany sweat glands a person has. Other factors like gender, weight, health and fitness level also affect the quantity of sweat produced. Heavier people need to spend more energy during physical activity and have higher sweat rates. In gyms, the people sweat more are generally observed to be the fittest. Physically fit persons can excercise harder and longer producing more sweat.
Sweating has many positive health impacts. Apart from the temperature-regulating effect, sweating excretes toxins, including arsenic, mercury, lead, and cadmium, improves circulation, offers pain relief and clear the pores. Exercise results in sweating. Sauna therapy is being used in treating rheumatoid arthritis and high blood pressure.