8 Metabolism of Healthy Man - . 



the investigators using these two chambers are concerned, there have not been 

 as vet any records of experiments in which there was continued muscular 

 activity of the subject approximating that of the ordinary routine of man about 

 a dwelling house. The apparatus has been used in most instances for studying 

 the influence of muscular work, particularly static work, upon the metabolism, 

 and but few of the results reported by these investigators can be used as indices 

 of the normal 24-hour metabolism. 



Metabolism during Specific Activities and Movements. 



During sleep. In general, any type of respiration chamber makes it wholly 

 impracticable to attempt to carry out 24-hour experiments in which a subject 

 lives with the same amount of muscular activity as if he were about his ordinary 

 life. There remains, therefore, at the present time the only alternative of 

 selecting such portions of different experiments, if possible made with the same 

 subject, as will enable us to obtain a correct impression of the metabolism 

 during separate muscular activities, represented by those of the daily life. Of 

 these by far the simplest, and fortunately thus far the most accurately deter- 

 mined, is the metabolism during sleep. A large number of experiments have 

 been made with the respiration calorimeter formerly at Wesleyan University, 

 at Middletown, Connecticut, in which the subjects rested with a reasonable 

 degree of comfort, and during the night were, in the majority of instances, 

 sleeping under fairly normal conditions. Up to the present time the results 

 of these experiments, although they have been presented in a number of reports, 

 have never been collected so as to throw definite light upon the metabolism of 

 normal, healthy men during sleep. 



During waking hours, influenced by rest, by variations in weight or height, 

 and by act of undressing and dressing. In order to obtain more satisfactory 

 results regarding the metabolism during rest, awake, a number of experiments 

 were made in which the conditions were those of comparative rest, the subject 

 remaining seated in an arm chair for the most part or all of a period of 3 to 8 

 hours. In some experiments food was taken in moderate amounts during the 

 period itself ; in others, the experiment was made either immediately after a 

 meal, or 12 hours or more after the last meal. A few other experiments were 

 made in which the subjects remained inside the chamber for 24 hours and the 

 results are useful for comparison with the previously published experiments. 



Another important point that has as yet been too little emphasized in the 

 reports of American investigators in this line is the influence of variations in 

 body-weight upon the metabolism. Accordingly, certain experiments were so 

 designed as to include the study of the metabolism of men of considerable 

 body-weight and also of men of unusual height. 



The average normal man dresses and undresses at least once a day. This 

 involves considerable muscular activity for a greater or shorter length of time 

 and his body is exposed to colder environment than the layer of air usually 



