Higher prevalence of exercise-associated hyponatremia in female than in male open-water ultra-endurance swimmers: the ‘Marathon-Swim’ in Lake Zurich The stress-associated hyponatremia has been studied for runners, triathlets and cyclists, but not in floats.$ We studied the prevalence of stress-associated hyponatemia at the marathon swimming in Zurich Lake and found amazing results. The can be read below https://pubmed.ncbi.nlm.nih.gov/21748367/