Abstract
Blood plasma cholesterol levels were followed in six experimental and six control subjects during a five-week training program (two-mile run for time, five days per week) and an eight-week detraining period. Plasma cholesterol levels were determined by the Duboff-Stevenson ultramicro method. Plasma cholesterol levels were significantly reduced during the course of intensive training. A temporary rise in plasma cholesterol occurred during exercise, probably indicative of fat mobilization and ultimate utilization during physical exercise. Plasma cholesterol levels returned to pretraining levels within four weeks after training was stopped. The diurnal and weekly blood cholesterol variations were rather small, 2 percent and 2.7 percent, respectively. The pathways by which exercise assists in the lowering of plasma cholesterol levels are discussed.