270 METABOLISM DURING WALKING. 



with the change to walking on these three days is not large in compari- 

 son with that shown in subsequent figures, the records in figure 33 

 being chosen for low grades and speeds. This increase does not become 

 apparent for approximately 10 to 15 minutes after the walking began, 

 and the rate of increase is relatively gradual. In the first two curves, 

 A and B, there is usually no noticeable fall in temperature when, as in 

 both experiments, the subject sat down at the close of the walking 

 periods. In the curve for the 10 per cent grade (curve C), a more rapid 

 rise in temperature is evident, with a tendency to a decrease between 

 the periods. This is apparent, also, after the second walking period 

 with the 5 per cent grade in curve B, when the temperature during 

 walking had reached 37.46 C. The curve for the 10 per cent grade 

 (curve C) shows a sudden fall in temperature following the change to 

 walking before the heat due to the exercise becomes noticeable. This 

 was possibly owing to change in resistance of the leads when the sub- 

 ject removed the blanket (see p. 37), or possibly to some change in the 

 position of the thermometer itself. 



In figure 34 are three different types of curves (February 2 and 25 and 

 March 8). Here the grades were 25 and 30 per cent, with speeds from 

 46 to 60 meters per minute. The curves all show an immediate rise in 

 temperature as soon as walking began, the response being within 

 2 or 3 minutes. This is in contrast to the curves in figure 33. The 

 rise in temperature in curve B was 1.23 C. during 28 minutes of walk- 

 ing, with a maximum of 38.30 C. With the same grade, but a speed 

 of 51 meters, the increase in three periods of walking was 1.45, 1.49, 

 and 1.52 C., respectively. (See curve C.) As soon as the walking 

 stopped and the subject sat down, the temperature fell as rapidly as it 

 rose and in approximately 40 minutes had reached the original level. 

 The effect of difference in position may be seen by the fact that the fall 

 at the end of the periods was greater and more rapid in curve C, when 

 the subject sat down with the cessation of walking, than in curve B, 

 when the subject stood in the intervals between the walking periods. 

 In the last period in curve B the walking was stopped, although the 

 measurement of the metabolism was continued somewhat longer. 

 While the rise in temperature ceased and the records almost imme- 

 diately showed a level when the walking stopped, the fall in temperature 

 in this case did not occur until the close of the period. Curve A in 

 this figure shows a record for an experiment in which but three observa- 

 tions were taken during each period. In this experiment the subject 

 sat down after each period and the temperature did not rise so high nor 

 fall so abruptly as in curve C, in which the grade and speed were greater 

 and the walking was continued through two periods and the corre- 

 sponding interval before the subject sat down. 



In figure 35 are four curves (February 29, 22, 17, and 18) of the tem- 

 perature changes when E. D. B. was walking with a speed of 68 to 50 



