Effects of dietary protein on physical work capacity during severe cold stress

¹ Division of Research, Lankenau Hospital, Philadelphia, Pennsylvania

The effect of four different diets (I: 3,000 kcal, 70 g protein; II: 3,000 kcal, 4 g protein; III: 1,500 kcal, 70 g protein; IV: 1,500 kcal, 4 g protein) on physical work capacity (treadmill running at 7.5 mph and 8.6% grade) was studied in normal young men at ambient temperatures of 22 and 8 C. In 9 days at 22 C there was no difference between the diets with respect to performance capacity. At 8 C no significant deterioration in physical work capacity was observed in nude subjects living on diet I for 9 days, but a marked deterioration occurred after 5 days on diet IV. A significant deterioration also occurred on diet II, as well as on diet III. It is thus evident that a marked reduction in calories or in protein causes deterioration in physical work capacity in men exposed to severe cold stress. In the cold, resting metabolism of men on all diets increased about twofold, resting pulse rate increased by about 20–30 beats/min on an average, and the pulse rate at submaximal work load was similarly increased. There was a significant increase in the urinary excretion of catecholamines in the cold.