METHODICAL STUDIES OF THE ESTIMATION OF T HE ELECTROLYTIC LOSS OF SODIUM, POTASSIUM, CALCIUM, AND MAGNESIUM THROUGH THE SKIN DURING A 10 KMRUN

An estimation of the electrolytic losses through the skin was evaluate d in a run over a distance of 10 km on a 400 m Tartan-trac. Na, K, Ca, and Mg excreted by the skin were collected in standardised clothing a nd thereafter washed out. The remaining electrolytes on the skin were collected by washing the body with deionized water. In addition, the c oncentrations of hormones and metabolites in blood before and after th e race were ascertained. Mean ambiant temperature and relative humidit y amounted to 21-degrees-C and 35 %, respectively. The mean performanc e was 40.5 min. and the average body weight loss was 1.45 kg. The only significant changes in the serum concentrations were the increases of free fatty acids and glycerol. This can be explained, together with a slight increase of glucose and a decrease of insulin, by a higher sym pathoadrenergic activity. In the mean 20 mg calcium, 5 mg magnesium, 2 00 mg potassium, and 800 mg sodium were lost by the skin per kg body w eight loss. Those amounts compared well with corresponding data found in literature. The described method can be proposed for further experi ments.