PHYSIOLOGICAL CHANGES IN TRANSITION. 277 



done. This can hardly be regarded as significant, and the probable 

 explanation lies in the technique, for, though the procedure was uni- 

 form, there was probably a variation of 10 to 15 seconds between the 

 cessation of work and the time of reading the pressure. Cotton, Rap- 

 port, and Lewis 1 have shown that the blood-pressure changes rapidly on 

 cessation of exercise, rising abruptly for the first 20 to 60 seconds and 

 then falling to normal in from 1 to 4 minutes. With such small differ- 

 ences in the blood-pressure as here reported, any error in the time of 

 reading would account for this lack of uniformity between the work 

 and the increase in the blood-pressure. 



The values found are similar in degree to those obtained for the same 

 subject when he was walking on a level (see table lla, p. 67), though 

 the increases over the standing values are here a trifle higher on the 

 whole. It is evident that these measurements do not cover a suffi- 

 ciently wide range of work to warrant an estimate of the effects of 

 grade walking upon the blood-pressure, other than to note an approxi- 

 mate increase of 10 mm. in blood-pressure when the work was 300 kg. m. 

 or less. This increase corresponds roughly to an average increase in the 

 oxygen consumption of 500 c. c. per minute, 2 or 9 c. c. per kilogram of 

 body-weight, which is of the same range as that found in the experi- 

 ments with level walking. Liljestrand and Stenstrom 3 with the sub- 

 ject N. S. during level walking found an oxygen increase of 850 c. c. 

 for a rise of 10 mm. in blood-pressure, while for the much lighter sub- 

 ject G. L. the increase in the oxygen consumption was 650 c. c. for an 

 increase of 8 mm. in blood-pressure. These increases would correspond 

 to an increase in the oxygen consumption of 8 and 10 c. c. per kilogram 

 of body-weight. 



PHYSIOLOGICAL CHANGES IN TRANSITION FROM STANDING TO GRADE WALKING 



AND THE REVERSE. 



It is of importance to find out, if possible, how quickly the body re- 

 sponds to the demands made upon it when varying amounts of muscu- 

 lar work are done and how soon it may be said that the body has 

 adapted itself to the new conditions, for the comparison of the results 

 obtained in this research presupposes that the metabolism has not 

 suffered any change in degree within the daily experimental period and 

 that a sufficient period of exercise has been allowed before the beginning 

 of each day's observations for the bodily functions to become settled. 

 It is, furthermore, important to determine how long the effects of mus- 

 cular work are present after the subject is again at rest. Observations 

 were accordingly made in the grade- walking experiments of the changes 

 in the rates of respiration, pulmonary ventilation, oxygen consumption, 

 and pulse during the transition from standing to walking and from 

 walking to standing. 



Cotton, Rapport, and Lewis, Heart, 1917, 6, p. 269. 2 See table 59, p. 229. 



3 Liljestrand and Stenstrom, Skand. Arch. f. Physiol., 1920, 39, p. 211. 



