Metabolism Experiment No. 68. 55 



Metabolism Experiment No. 68. 



This experiment, which lasted two days, followed immediately a series of 

 experiments covering 11 consecutive days, made with the same subject inside 

 the respiration calorimeter. The previous series has been reported elsewhere." 



While in the majority of the fasting experiments here reported, accurate 

 knowledge of the metabolic activity before the fast was not available, in this 

 instance the metabolism for several days before the fasting period was accurately 

 measured. 



Three series of experiments preceded the fasting period. The first was a 

 3-day experiment, during which the subject was engaged in hard muscular 

 labor riding a bicycle ergometer 15 for 6 hours each day and received a diet 

 furnishing about 100 grams of protein and 4630 calories of energy per day. 

 The diet during this period consisted in large part of carbohydrates. The 

 second was also a work experiment of 3 days' duration, during which a diet 

 containing approximately the same amount of nitrogen as the preceding, but 

 with slightly increased energy, averaging not far from 4750 calories per day, 

 was given. During this experiment the diet consisted in large part of fat, 

 chiefly in the form of cream. The third series consisted of 4 experiments, 

 beginning with a 1-day experiment, during which a diet containing 19.11 grams 

 of nitrogen and 5393 calories of energy, chiefly in the form of cream, was 

 provided. On this day the subject did an unusual amount of muscular work 

 on the bicycle ergometer, riding until far into the night. The severe work day 

 was followed by a rest experiment of 1 day, during which the subject spent the 

 most of his time in bed, recuperating from the excessive work of the preceding 

 day. The diet contained 15.4 grams of nitrogen and 2369 calories of energy. 

 During the next experiment, which was also of 1 day's duration, the subject 

 prepared the ergometer and removed clothing for riding, but immediately 

 dressed himself and did not ride, the purpose being to determine the energy 

 required for the extraneous muscular work other than that involved in riding 

 the ergometer. The diet for this day furnished 14.11 grams of nitrogen and 

 2062 calories of energy. On each of the two following days the subject rode 

 the bicycle ergometer for 6 hours. The riding corresponded to the free leg- 

 motion of coasting, since no resistance was applied to cause the subject to do 

 work. During these two days, which are of more especial interest in considering 

 the subsequent fasting period, the diet supplied about 11 grams of nitrogen 



14 U. S. Dept. Agriculture, Office of Exp. Sta. Bui. 175. 



15 The bicycle ergometer is an apparatus for measuring accurately the external 

 muscular work of riding. It is practically a stationary bicycle. For a description, 

 see Carnegie Institution of Washington Publication No. 42, p. 164. 



