38 METABOLISM DURING WALKING. 



apparatus used consisted of an Erlanger sphygmomanometer, with 

 which a permanent record was secured on the kymograph. Only the 

 systolic pressure, however, was noted. To assist in determining this 

 point, we also employed a Nicholson sphygmomanometer, placing a 

 cuff on the forearm and noting the first indication of the pulse from the 

 movement of the Fedde pith-ball. 1 The pressure was then read on the 

 Erlanger sphygmomanometer. This double method of securing the 

 systolic pressure was found to be more satisfactory under these special 

 conditions than the use of a stethoscope on the brachial artery or placing 

 entire reliance upon the tracing of the pointer on the Erlanger sphyg- 

 momanometer. 



The cuffs were placed on the subject's right arm before the experi- 

 ment began and were worn by him during the entire forenoon. In the 

 standing experiments, three determinations were made as near to the 

 second, sixth, and tenth minutes of each period as possible. In the 

 walking experiments, the pressure was applied towards the end of the 

 usual preliminary walk. When all was in readiness, the treadmill was 

 stopped and two determinations of the systolic pressure were made as 

 quickly as possible. The walking then began again immediately and 

 the period commenced with but little loss of time, usually not more 

 than 1 or 2 minutes. At the close of the period, while the subject was 

 still walking, the pressure was again applied, and as soon as the tread- 

 mill stopped a second series of records was secured. The average of 

 these two observations, namely, the records after 10 minutes of pre- 

 liminary walking, and after 10 or 12 minutes of walking in the period 

 proper, are recorded as the blood-pressure for the walking period. It 

 should be clearly understood, however, that these values were made 

 while the subject was standing and 10 to 20 seconds after he had 

 stopped walking. 



ROUTINE OF EXPERIMENTS. 



The approximate routine of an experimental period during a walking 

 experiment was as follows: On the arrival of the subject at the Labora- 

 tory, records were made of the last meal taken and the hour it was 

 eaten to insure that the subject was in a post-absorptive condition. 

 The electrodes for the pulse-record were then adjusted, and if the 

 exercise was to be severe, a change was generally made to a walking- 

 suit. The man was then weighed with clothing, after which the rectal 

 thermometer was inserted. When the subject mounted the treadmill, 

 a safety belt attached to the ceiling was buckled loosely about his waist. 

 The counters for recording the number of steps and the step-lift were 

 connected and read, also both of the revolution counters on the tread- 

 mill. The sub j ect then began the preliminary walking period. During 

 this period a certain amount of air was withdrawn from the ventilating 



1 Wiggers, Circulation in health and disease, Philadelphia and New York, 1915, fig. 53, p. 198. 



