Effects of exercise in the cold on blood clotting and platelets

Abstract

The tendency to blood clotting as measured by Lee-White clotting time (CT), partial thromboplastin time (PTT), and platelet adhesiveness (PAC) was studied in 10 normal subjects before and after a standardized bicycle exercise done at 25 C inside and at an average temperature of -20 C outside. Inside exercise caused a shortening of CT from 674 to 465 sec, of PTT from 88 to 78 sec, and PAC increased from 65,000/mm3 to 185,000/mm3; P < .05 for all tests, suggesting an increased tendency to blood clotting. In contrast, exercise done in the cold produced no significant changes in these parameters. Heart rate, rectal temperature, and changes in plasma proteins were similar for both types of exercise. platelet adhesiveness; clotting time Submitted on July 20, 1964