Biochemical and hematological changes following the 120-Km open-water marathon Swim

Data on physiological effects and potential risks of a ultraendurance swimming are scarce. this report presents the unique case of a 61-year old athlete who completed a non-stop open-water 120-km ultramarathon swim on the warta river,poland. pre-swimming examinations revealed favorable conditions (blood pressure,110/70 mmhg; rest heart rate,54 beats/minute,ejection fraction,60%,20.2 metabolic equivalents in a maximal exercise test). the swimming time and distance covered were 27 h 33 min and 120 km,respectively. blood samples for hematological and biochemical parameters were collected 30 min,4 hrs,10 hrs and 8 days after the swim. the body temperature of the swimmer was 36.7 °c before and 35.1 °c after the swim. the hematological parameters remained within the reference range in the postexercise period except for leucocytes (17.5 and 10.6 x g/l noted 30 minutes and 4 hours after the swim,respectively). serum urea,aspartate aminotransferase and c-reactive protein increased above the reference range reaching 11.3 mmol/l,1054 nmol/l/s and 25.9 mg/l,respectively. symptomatic hyponatremia was not observed. although the results demonstrate that an experienced athlete is able to complete an ultra-marathon swim without negative health consequences,further studies addressing the potential risks of marathon swimming are required. © journal of sports science and medicine.