EXPERIMENTS WITH HORIZONTAL WALKING. 175 



at the different speeds. Apparently the exercise of walking at the 

 normal speeds used for the most part in this research was not sufficient 

 to produce any marked changes in body-temperature. Referring again 

 to table 47, in which it has been necessary to compare only the average 

 temperatures, it is seen that although the highest absolute temperature 

 and largest increases over the standing values are with the highest 

 speeds, the lowest speed also has a high average temperature as well as 

 large increase, and that the increases over the standing temperatures 

 are irregular. The average walking temperature would depend upon 

 the duration of walking as well as upon the speed. Consequently, no 

 definite statement as to the influence of speed can be made other than 

 that, in the intermittent periods here conducted, the maximum in- 

 crease for any speed below 100 meters per minute did not exceed 

 0.5 C., and that for moderate speeds the temperature increase would 

 probably be not far from 0.25 C. 



BLOOD-PRESSURE DURING HORIZONTAL WALKING. 



The increase in the supply of oxygen to the tissues with increased 

 demand due to exercise is dependent upon a chain of processes. The 

 increase in pulmonary ventilation and pulse-rate, the change in the dis- 

 tribution of the blood-flow to those muscles more in need of oxygen, and 

 the general increase in the blood-flow itself, all contribute to the imme- 

 diate supply of oxygen. The increase in the blood-flow is one of the 

 largest, if not the largest, factor in maintaining this addition to the 

 oxygen-supply, and Krogh and Lindhard 1 have shown that during 

 work the blood-flow may be eight times that during rest. This increase 

 in blood-flow is, at least above certain limits, accompanied by an in- 

 crease in blood-pressure. It thus becomes of interest to record the blood- 

 pressure during periods of exercise, and this was done with E. D. B. for 

 both the standi ng and walking experi ments over a period of several weeks . 

 During this time there were 13 days on which records of the blood-pres- 

 sure were made for both standing and horizontal-walking periods. These 

 horizontal- walking values are recorded in table 1 la (p. 67) . It should be 

 recalled that they were taken just prior to and immediately following 

 the periods of walking proper, as it was not possible to read the pres- 

 sure during the act of walking. (See p. 37.) Cotton, Rapport, and 

 Lewis 2 have recently shown that the blood-pressure immediately on 

 the cessation of exercise indicates little or no increase above the rest- 

 ing value, but within 10 seconds it begins to increase and continues to 

 rise for a period of 30 to 60 seconds, after which it again tends to fall to 

 normal value. While it is possible that the readings as reported by us 

 may not have occurred at the point of maximum pressure following 

 walking, it is quite certain that the readings were close to it and beyond 



'Krogh and Lindhard, Skand. Arch. f. Physiol., 1912, 27, p. 100. 

 'Cotton, Rapport, and Lewis, Heart, 1917, 6, p. 269. 



