During a winter swimming competition, 78 swimmers, 44 men (age 17-70) and 34 women (age 16-66), were examined before and after the race. The distances swum were from 100 to 1000 m, the water temperature (Tw) was 5.8 oC.
Swimming times ranged between 3:20 and 22 minutes. Our results confirm a considerable stress response expressed by irritation of the sympathetic nervous system resulting in an increase in FFA and the leukocyte count.
However, the entire endocrine system was also activated, manifested in an increase in cortisol, prolactin and in changes to thyroid hormone levels. Biomarkers NGAL and cystatin C indicate kidney ischemia with possible reduced GFR.