Mav 26, 1904] 



NA TURE 



91 



Exercise. 



The fundamental effects of exercise on the blood pressure 

 may be readily studied in an epitomised form by placing 

 Jhe pad of the ha'modynamometer over a small superficial 

 artery, like the superficialis vols, and then throwing all 

 the muscles into a state of tension for sixty seconds (the 

 inn on which the observation is made being excluded from 

 I lie contraction). In Fig. 4 you observe that the complete 

 .nterial pressure curve of muscular contraction is made up 

 of two elevations, (a) primary and (c) secondary, separated 

 by a fall (15) which is just as decidedly below the normal 

 [iressure as the second rise is above it. The first elevation 

 \.\) is synchronous with the tension, and the second (c) 

 appears after the muscles are relaxed. 



Now these oscillations of the arterial pressure are all 

 seen on a larger scale in ordinary exercise, each stage 

 being, of course, prolonged in proportion to the duration 

 of the exercise. The primary rise is invariably followed 

 by a gradual fall, even during the continuance of the 

 exercise, and by a rapid and decisive fall on its cessation, 

 and that fall is succeeded during rest by a second 

 rise. 



Sir Lauder B 



and Dr. Tunnicliffe are, I believe. 



MUSCULAR TENSION 

 I MINUTE 



3 MINUTES 



-The effect of ml 

 1 ; (8) fall < 



the arterial pressure ; (a) rise from r 

 elaxing the muscles ; (c) .secondary rise during rest. 



the only observers who have furnished trustworthy data 

 un the blood pressure in man, both during muscular move- 

 ment and immediately after its cessation, and their data 

 accord with my own.' 



The secondary rise of blood pressure which I have in- 

 variably found to supervene during rest after exercise does 

 not, however, seem to have been recognised by other 

 observers. 



Exercise invariably increases the exudation of tissue- 

 lymph. Inasmuch as it is rapidly absorbed on the cessation 

 of exercise, the observation must be made without delay. 



How are these effects of exercise produced? According 

 10 Ludwig and Gaskell (Ludwig's "Arbeiter," 1877), 

 during a short tetanus the flow from the elTerent vein of 

 the muscle, after the first spurt of blood, may fall to 

 practically nil. Therefore we may infer that muscular 

 contraction causes partial or temporary occlusion of the 

 intra-muscular vessels, and that this increase of peripheral 

 resistance, along with reflex cardiac stimulation, will go 

 far to explain the rise in the arterial pressure. 



At the same time, the capillary pressure within the muscle 



1 " Remarks on the Effect of Resistance Exercises upon the Circulation 

 in Man, Local and General," by Sir Lauder Brunton ,ind F. W. Tunnicliffe, 

 M.D. (Brit .I/,-,/. Journ-, October 16, 1S97.) 



NO. 1804, VOL. 70] 



will fall, and lymph will not be exuded. But the state of the 

 circulation is different in the non-muscular parts, for all 

 the blood pressures (arterial, capillary, and venous) are 

 markedly raised during the sustained tension of the muscles. 

 Hence the effusion of lymph in the finger. On the other 

 hand, when the contraction ceases, the intra-muscular 

 capillary pressure will rise, and lymph will then be 

 effused into the muscles. That the muscles when relaxed 

 after contraction become full of blood is shown by the work 

 of Ludwig and his pupils, and by .Sir Lauder Brunton and 

 Dr. Tunnicliffe, who have furnished graphic evidence of 

 the dilatation of the intra-muscular arteries which follows 

 contraction {op. cit.). 



As after food so after exercise the contractibility of the 

 muscles (as indicated by the tension test) diminishes in pro- 

 portion to the amount of lymph effused. 



Exercise likewise provides us with some instructive facts 

 as to how tissue-fluid is removed. Observation has shown 

 that a short muscular contraction of si.xty seconds will 

 produce two effusions, one during the contraction which 

 is entirely absorbed in sixty seconds, and another which is 

 immediately afterwards thrown out, and disappears jusfas 

 quickly, so that in four minutes we have two successive 

 effusions which entirely clear up. The rapidity with which 

 lymph disappears from the tissues in a state 

 of rest certainly favours the notion of absorp- 



tion rather than that of transmission along the 



lymphatics. Now, experimentation on animals 

 has shown that muscular action of some kind 

 is necessary to ensure a flow of lymph along 

 the lymphatics, so we may conclude that during 

 exercise the muscular action will more par- 

 ticularly favour that passage for the lyinph. 



F.\riGUE. 

 Observation has shown that the rise in the 

 arterial pressure produced during the con- 

 tinuance of exercise becomes less and less pro- 

 nounced in proportion to the duration of the 

 exercise ; for example, the initial increase of 

 from 15 to 20 mm. gradually subsides until, 

 after the lapse of a certain time (which varies 

 with the tone of the individual and with the 

 external temperature), the arterial pressure 

 will not exceed 100 mm. Hg, and if the exercise 

 is further continued it will even fall lower, to 

 95, 90, or 85 mm. This point was also 

 observed by Sir Lauder Brunton and Dr. 

 Tunnicliffe. 



Why should the rise of pressure, normally 

 induced by exercise', be effaced or even re- 

 placed by a fall when e.xercise is prolonged? 



Inasmuch as the lymph exuded during 

 exercise obstructs the contractile pressure of 

 the muscular fibres on the intra-muscular 

 arteries and arterioles, the peripheral resist- 

 ance caused by e.xercise will be reduced, and the arterial 

 pressure will gradually fall. In fatigue, no amount of 

 will e.xerted over the muscles can raise the arterial pressure 

 at all ; the muscles, though capable of ordinary contrac- 

 tion, become, as it were, lymph-logged. But massage 

 quickly disperses the lymph, and the contractibility is re- 

 stored. Human instinct, without knowing the "why," 

 practised what is now taught by physiological inquiry. We 

 read in the " Odyssey " how the women rubbed and kneaded 

 their weary heroes returned from battle, and thus invigor- 

 ated them, and we know that from time immemorial rubbing 

 was the sovereign remedy for fatigue. 



The physiology of fatigue includes another important 

 factor, namely, diminished gravity control over the blood 

 pressure. The outcome of exercise is the production of 

 hypotonia in the vaso-motor mechanism, which is the central 

 fact, as it were, of fatigue. 



Rest. 

 During rest after exercise there is developed a steady 

 and persistent rise of the blood pressures and a correspond- 

 ing effusion of lymph, and the volume and duration of this 

 second outflow- of lymph are always proportionate to the 

 vaso-dilator or reducing effect of exercise. The physio- 

 logical intent of it is to repair and recharge the muscles, 



