Performance Capacity in Acute Starvation With Hard Work

Abstract

Four men were subjects for a 2.5-day fast (series A) and 12 men for a 5-day fast (series B). The avg. total calorie deficits were estimated to be approx. 9000 and 16,000 cal. Mean wt. losses were 4.5 kg. (6.7%) and 7.8%). The men walked at 3.5 mph on a 10% grade (an avg. expenditure of 550 cal/hr.) for 4 hrs. each day in series A and for 3 hrs. in series B. Few signs of loss of fitness were observed during the 1st day. On the morning of the 2d day, work pulse rates increased 10-15 beats/min., work ventilation increased and blood sugar decreased 25 mg./l00 ml. Only a small increase in work pulse rate (5 beats/min.) was noted during the remainder of the fasting period. Ability to perform exhausting "anaerobic" work was definitely impaired after the 1st day of starvation. On the 2d day the score of the Harvard Fitness Test decreased to 70% of the control value and on the 4th to 40%. There was no change in the max. O2 intake/kg, of body wt. during the course of the 5-day fast. The physiological response to a fixed anaerobic task showed no deterioration at the end of the 1st day, as measured by blood lactate concn. On the 5th day there was a definite increase in blood lactate concn. and in the 10-min. O2 debt. Recovery of performance was studied after 4 and 5 days of refeeding.