246 



METABOLISM OF HEALTHY MAN. 



minute. The oxygen absorbed amounted to 0.3 gram per minute, and the 

 heat production to 1.2 calories per minute. It is thus seen that for each act 

 of opening and closing the food aperture, which, on an average, occupied 25 

 seconds, the excretion of carbon dioxide and the heat production were approxi- 

 mately the same as in one minute of sitting (resting), or an increase of over 

 100 per cent. If the actual time required to carry out the operation is taken 

 into consideration, the excess in heat production over that which would be pro- 

 duced during the time required for the operation would be 200 to 300 per cent. 



When it is seen that rising from a chair, taking one step, and returning 

 may involve an increased heat production over the resting metabolism of 100 

 per cent or more, it is clear that the sum total of minor body movements in 

 the course of a day may actually accumulate to a considerable amount and 

 thus raise the heat production during resting metabolism much more than one 

 would ordinarily appreciate. This makes it extremely difficult to estimate 

 beforehand the energy output of individuals where the minor muscular move- 

 ments are not satisfactorily recorded. The experiments here reported are the 

 result of an attempt to accumulate data regarding some of the simpler opera- 

 tions or movements which may take place in ordinary life. They have a prac- 

 tical value in connection with the interpretation of certain of the experiments 

 made with this apparatus, but they likewise throw considerable light upon the 

 metabolism involved in a simple body-movement. 



Table 103. Increase in the metabolism in food-aperture experiments as compared 



ivith, metabolism during rest. 



For explanation of this series of movements see pp. 61 and 62. 



