121 



BLOOD PRESSURES IN MAN, NORMAL AND PATHOLOGICAL 313 



tolic pressure. The methods adopted by Bo wen (19) (systolic pres- 

 sures only) and by Lowsley (86) (systolic and diastolic by the Erlanger 

 sphygmomanometer) enabled the course of the pressure changes to be 

 followed throughout the period of exercise (stationary bicycle) . They 

 found a rapid rise at first, reaching a maximum in a number of minutes, 

 (Bowen, 5 to 10 minutes, Lowsley, 5 to 25 minutes) then slowly de- 

 clining and after the end of the exercise sinking to normal or subnor- 

 mal levels. 



McCurdy (96) measured systolic pressure during brief maximal 

 effort (heavy lifts involving thoracic fixation, etc.) lasting about 5 

 seconds, and found an average rise from 111 mm. before the effort to 

 180 mm. during and 110 after. 



Measurements made "immediately" or at certain periods after- 

 wards are not valid guides to the actual height of the pressure during 

 the exercise, though such have been used by some observers in com- 

 paring the blood-pressure response to effort in different types of sub- 

 jects. Thus some observers have taken estimations half a minute 

 after the termination of exercise as a standard. Cotton, Lewis and 

 Rapport (28) making repeated measurements found a fall to, or nearly 

 to, normal in 10 seconds then a rise reaching a maximum in 20 to 60 

 seconds, there is then a gradual fall, reaching the resting level in from 

 1 to 4^ minutes after the end of the exercise (20 pound dumb-bells). 

 Similarly Chailly-Bert and Langlois (27) recorded a fall in 5 seconds 

 after the cessation of exercise to about normal, followed by a subsequent 

 rise. Graupner (58) and Barringer (9) had previously described a 

 secondary rise after the end of the period of exertion with a Zuntz 

 ergometer and with dumb-bells respectively. These observations 

 mainly deal with systolic pressures. The interpretation put upon their 

 results by Cotton, Lewis and Rapport is that, assuming the veins to 

 be depleted during the period of exertion, these veins fill up with blood 

 when the muscular action ceases and so cut down the return of blood 

 to the heart and the arterial pressure, until the veins have refilled and 

 the inflow into the heart is restored, leading to the subsequent rise in 

 presence of the continuance of the factors, other than the pumping 

 action of the muscles, operative during the exercise. 



This interpretation has been disputed by Bainbridge (6) who re- 

 gards the veins as being full during the period of exertion, and the fall 

 of arterial pressure to be due to the cessation of the pumping action 

 of the muscles inducing a momentary stasis of blood in the capillaries, 

 involving a temporary diminution of the venous return to the heart. 



