264 CARNEGIE INSTITUTION OF WASHINGTON. 



half of their caloric requirements prior to the test. Another group of 12 

 students volunteered to serve as a control group, and they were later also 

 subjected to a short period of restricted diet. As a result of these two series 

 of tests, it has been concluded that with adults very considerable drafts upon 

 body material, either as a result of complete withdrawal of food or of prolonged 

 curtailment of the food-supply, msiy be made without great discomfort and 

 without permanent detriment. We may further say that a moderate curtail- 

 ment of diet is productive of neither distress nor permanent impairment of 

 the lower animals. It is of special interest to note that one of the most 

 important deductions from these series of observations on humans has been 

 taken up from a practical point of view in the study of animal nutrition. 

 This paper was given before the Medical Department of the University of 

 Buffalo, New York, June 3, 1921, as the second Harrington Lecture. 



(8) Gaseous exchange and physiological requirements for level and grade walking. Henry 

 Monmouth Smith. Carnegie Inst. Wash. Pub. No. 309 (1922). 



This publication covers the results of an extended study of the metabolism 

 and energy requirements of several men during standing and during both 

 horizontal and grade walking. Observations were made also on pulmonary 

 ventilation, respiration-rate, body-temperature, and pulse-rate, the latter by 

 aid of the string galvanometer. Measurements were obtained of the work 

 performed in lifting the body by the heel-and-toe action of walking. The 

 energy expended in transporting one kilogram of body-weight a horizontal 

 meter and for one kilogrammeter of grade work and the efficiency with which 

 this work was performed are reported. A study was made of the response in 

 the pulmonary ventilation, respiration, and pulse as the subject changed from 

 rest to work; also of the time necessary for equilibrium to become reetsablished 

 after the walking had ceased. 



It was found that the average standing metabolism for all the subjects was 

 1.18 calories per kilogram of body-weight per hour, or 28.4 calories per 24 

 hours. By using their standing requirements as a basis, it was established that 

 with the two main subjects (W. K. and E. D. B.) the increase in energy 

 expended due to horizontal walking was 0.490 and 0.478 gram-calorie, respec- 

 tively, for each horizontal kilogrammeter of work done. Variations in speed 

 under 80 meters per minute had no effect upon the results, but above that point 

 the energy expended increased proportionately with the increase in speed. 



In grade walking the total heat expended increased uniformly per kilogram- 

 meter of work performed at each grade, but was somewhat less when the same 

 amount of work was derived from a high grade and a low speed than when due 

 to a low grade and a high speed. The total outlay was from 12 to 15 gram- 

 calories per kilogrammeter for amounts of work ranging from 300 to 600 kilo- 

 grammeters per minute. 



From the results of this study it may be said that the net efficiency with 

 which a person can walk up grade is not far from 30 per cent when the work is 

 under 500 kilogrammeters per minute, but with greater amounts of work the 

 efficiency decreases as the work increases. 



The pulmonary ventilation and pulse-rate in grade walking increased rapidly 

 as the work performed increased. The respiration-rate also increased. The 

 pulmonary ventilation showed for W. K. and E. D. B. an increase of approxi- 

 mately 350 to 800 per cent when 900 kilogrammeters of work were performed. 

 For a similar amount of work the pulse-rate increased some 90 to 125 per cent 

 and the respiration about 75 to 100 per cent. 



In the transition from standing to grade walking, the body appeared to 

 adjust itself to the new demands for increase in the pulmonary ventilation, 



