Changes in lipoprotein profiles during intense military training.

The effects of intense military training on lipoprotein concentrations were monitored in a group of 44 Navy trainees. Dietary intakes and lipoprotein profiles were obtained before and after 5 weeks of physical conditioning and after 5 days of continuous, extremely intense physical and psychological stress. Body weight did not change significantly and dietary intakes were consistently high in saturated fat and cholesterol. After physical conditioning, serum total cholesterol and triglyceride concentrations were unchanged, while high-density lipoprotein (HDL) concentrations increased 31% (p less than 0.05). After 5 days of severe stress, total cholesterol and low-density lipoprotein concentrations decreased 17.2% and 30%, respectively (p less than 0.05), whereas HDL concentrations increased 12.1%. These data indicate that marked changes in lipoprotein profiles occur, not only with long-term physical conditioning, but also with strenuous training that lasts several days, despite high energy, fat, and cholesterol intakes.