298 



METABOLISM DURING WALKING. 



that the pulse-rate per minute could be easily counted, but the time- 

 intervals on the paper were too small for the accurate measurement 

 of the duration of the individual pulse-cycle. Therefore, in order to 

 have our period of measurement long enough to secure reasonably 

 accurate readings to 0.01 second, the cycles were measured in groups 

 of 10. The results given accordingly represent the average duration 

 of a pulse-cycle as calculated from the measurement of the time re- 

 quired for a group of 10 pulse-cycles. The changes in the average 

 duration as thus determined give a clearer measure of altering heart- 

 rate than could be obtained by the usual method of counting the pulse. 

 The changes in the duration of the pulse-cycle in the transition from 

 standing to walking are shown in the four curves in figure 39. In this 

 figure each point on the abscissa represents the average of 10 consecu- 

 tive pulse-cycles, while the duration of the pulse-cycle is given in 0.01 

 second as the ordinate. The pulse-rates equivalent to the measured 

 durations are shown on the right. As the duration of the cycle is 

 changing, the time required for a group of cycles also changes, but the 

 approximate elapsed times are indicated for groups of 100 cycles by 

 email figures and inclusion marks below the curves. The point at 

 which the subject began to walk is shown on the curve by the letter X. 



/' 



100 100 200 300 100 

 PULSE CYCLES 



100 200 300 100 100 200 100 100 200 300 



Fio. 39. Duration of pulse-cycles of E. D. B. in transition from standing to 

 grade walking, aa indicated by average cycle duration for measured 

 groups of 10 pulse-cycles. 



Beginning of walking at X. A, Feb. 18; B, Feb. 21; C, Feb. 19; D, Feb. 22. 

 The time required for groups of cycles, varying in number, is indicated by 

 email figures and inclusion marks at the bottom of the charts. 



The cycles to the left of X accordingly represent measurements for the 

 standing position and to the right those for grade walking. The 

 average grades and speeds used in the walking are indicated for each 

 curve. 



In figure 39, a noticeable feature is the wide variation in the duration 

 of the pulse-cycles while the subject was standing, as shown by the 

 variability of the portion of each curve at the left of X. The measure- 

 ments for the standing position were made with the same degree of 

 accuracy as those obtained during the walking, and there is no reason 

 to doubt the presence of these wide differences. Measurements of 



