POST-SWIM ORTHOSTATIC INTOLERANCE IN A MARATHON SWIMMER

Two swims (1993 and 1994) are described which led to post-swim orthost atic intolerance and one episode of syncope in a 50/51-yr-old well-tra ined and experienced marathon swimmer. The swims of 33 km and 38 km to ok 12 h 30 a and 17 h 35 min, respectively. Water temperature in each swim was above 23 degrees C and rectal core-temperature stayed above 3 7.0 degrees C. Air temperatures differed, ranging from 23 degrees to 3 7 degrees C and 15 degrees to 21 degrees C, respectively. Regular flui d consumption totalled approximately 5.0 and 6.0 l, respectively. Fift een minutes after completing the 1993 swim, the swimmer experienced or thostatic intolerance and fainted at the lakeside; hospital tests reve aled an elevated creatine phosphokinase (CK) of 521 U . l(-1). The 199 4 swim was abandoned due to severe muscle cramps and CK was found to b e markedly elevated at 909 U . l(-1). Orthostatic intolerance was reco rded in both cases; however, no cardiac abnormalities were found. Afte r overnight rest and intravenous saline infusions of 3.0 and 1.5 l, re spectively, the orthostatic intolerance was relieved. Based on previou s descriptions of exercise-associated collapse in marathon runners, th e swimmer's orthostatic intolerance and syncope are attributed to bloo d pooling in his legs due to inactivation of the venous muscle pump on completion of the swim.