Blood-pressure response to swimming in ice-cold water.

The cardiovascular responses to cold were studied in a group of 28 subjects who enjoyed swimming in ice-cold water in winter ("ice-bears"). History and clinical examination had revealed no abnormalities except hypertension (180/105 mm Hg) in 1, while 3 other subjects had a diastolic value of 95 mm Hg. Systolic blood-pressure increased significantly while the subjects were waiting undressed in cold air in the cabin by the pond. Neither immersion nor swimming in the ice-cold water caused further increase in systolic blood-pressure, and diastolic blood-pressure showed only a modest rise. 4 min later, blood-pressure had returned to control values. Electro and vector cardiographic signs remained unchanged. Although very high pressures were recorded in several subjects, no signs of left ventricular hypertrophy or of cardiovascular of cerebrovascular damage could be detected.