PHYSICAL ENDURANCE AND ACTIVITY. 647 



is by no means sufficiently large to in any wise account for the actual 

 changes in the net energy consumption. On the other hand it is true 

 that horizontal walking is the easiest part of a man's activity to main- 

 tain up to a normal standard amount under conditions of physical 

 weakness and discomfort. A man can walk with comfort and pleasure 

 when he would avoid running and exercise more strenuous than walk- 

 ing, unless prompted by necessity or some special motive. It seems 

 probable, therefore, that if we had quantitative estimates for physical 

 activity more strenuous than walking, these might follow the fluctua- 

 tions found with the walking, and the variations in activity might con- 

 ceivably be larger. It is not surely indicated that they would be large 

 enough, however, to account for the energy differences from period to 

 period of the experiment. Such correlations between activity and 

 energy intake are not definitely proved in this research to be physio- 

 logical necessities. The influence of mental attitude, ranging from 

 depression, with much restricted diet, to the feeling of euphoria, with 

 more liberal diet, would make for a similar correlation. 



In interpreting the records of activity and in attempting correlations 

 with diet, clear distinction must be made between those periods in the 

 research that should more strictly be considered as transitional periods 

 and those that are maintenance periods. With Squad A we have at 

 the beginning of the experiment a distinctly transitional period. Imme- 

 diately after the Thanksgiving recess we have a period of greatly 

 reduced diet to overcome the excess eating during this vacation. A 

 similar short transitional period appears in the early part of January. 

 With Squad B the entire reduced diet period must be considered as a 

 transitional period. Strictly speaking, the two periods of preemmently 

 maintenance levels for Squad A are those about the middle of Decem- 

 ber and the latter part of January. 



For purposes of analysis it is quite unfortunate that the transitional 

 period in the early fall was coincidental with the period of fair weather, 

 thus contributing towards considerable walking. After October 18 

 it is apparent from the figures in the last colunm of the table that there 

 -is no pronounced tendency for these subjects to reduce materially their 

 physical activity, at least as indicated by the pedometer records. It 

 should still be pointed out, however, that this table does not indicate 

 the probable number of miles that these men would have shown 

 in the week prior to dietetic restriction. 



PEDOMETER CONTROL WITH SQUAD B ON NORMAL DIET. 



To secure important evidence of the probable activity as recorded 

 by the pedometer of a homogeneous group of college men not on diet, 

 arrangements were made for observations on Squad B during the 

 period of December 13 to 19. The homogeneity of these squads is, of 

 course, difficult to determine with strictest accuracy. They were 



