CORBESP ONDENCE. 



841 



CORRESPONDENCE. 



THE PHYSIOLOGY OF EXERCISE. 

 Messrs. Editors : 



"TTTHILE all must agree with Professor 

 VV Richards as to the importance of 

 physical exercise to the brain-worker, there 

 are some points in his article on " The In- 

 fluence of Exercise upon Health," in the 

 "Monthly" for July, 1886, requiring com- 

 ment. 



On page 328 he says : " When we use 

 our muscles, their contractile force upon the 

 blood-vessels helps the blood along its chan- 

 nels, and thus takes a little labor from the 

 propelling heart. It beats faster, but with 

 less effort." 



It is admitted that contracting muscles 

 by their lateral pressure promote the flow of 

 blood through the veins; but the work of 

 the heart is not lessened thereby, because 

 the force of the heart-beat is not expended 

 in propelling the blood through the veins, 

 but (according to Foster) in expanding the 

 elastic arteries and overcoming the friction 

 between the blood and the walls of the ar- 

 teries and capillaries. This friction is called 

 the peripheral resistance. Now, whatever 

 diminishes the caliber of the terminal arter- 

 ies and capillaries increases the peripheral 

 resistance ; and, if the contracting muscles 

 have any effect upon these vessels, it is to 

 lessen their caliber and so increase the pe- 

 ripheral resistance, thus throwing more work 

 upon the heart. 



The heart beats faster, but does it beat 

 with less effort ? Du Bois-Reymond (" The 

 Physiology of Exercise," " Popular Science 

 Monthly," July, 1882) says: "Under con- 

 tinuous severe exertions, as in mountain- 

 climbing and long walks, the heart begins 

 to beat faster and more strongly ; because, 

 according to Traube, it is stimulated by ex- 

 cess of carbonic acid formed in the laboring 

 museles; according to Johann Miiller, be- 

 cause it participates in a by-motion." 



How is it, if muscular exercise lessens 

 the work of the heart, that excessive and 

 long-continued muscular exertion causes hv- 

 pertrophy and even valvular disease of that 

 organ ? Yet such is the case, according to 

 such eminent authorities on medical matters 

 as Drs. Da Costa, A. L. Loomis, the late 

 Austin Flint, and others. This is a matter 

 of great importance from a medical stand- 

 point, for, if muscular exercise lessens the 

 work of the heart, our medical writers have 

 all gone wrong in saying that the most es- 

 sential item in the treatment of a diseased 

 and overtaxed heart is rest. 



Again, the professor quotes Maudsley as 

 follows: "By one organic element of "the 



body the blood is purified from the waste 

 matter of a higher element, which would be 

 poisonous to it." This is undoubtedly true. 

 The lungs, kidneys, and other excreting 

 organs certainly do eliminate materials 

 which would be poisonous to other organs. 

 But Professor Richards applies this remark 

 to the muscular and nervous systems, which, 

 I think, he is not warranted in doing, as I 

 shall endeavor to show. 



He says (page 332, July "Monthly"): 

 " A tired brain and quivering nerves may 

 not be more wearied by physical exercise, 

 but may be refreshed by it. This refresh- 

 ment may result from two processes : First, 

 by drawing the excessive blood-supply from 

 the before active organs ; and, secondly, by 

 purifying the blood so that it may be ready 

 to properly nourish the brain." 



In the first place, it is not the excessive 

 blood-supply that makes the brain tired, the 

 increase of blood being caused by the in- 

 creased demand of the functionally active 

 organs. In the second place, contracting 

 muscles, as the result of the chemical 

 changes that take place in their substance, 

 form lactic acid, keratin, and carbonic acid. 

 The last, according to M. Foster ("Text- 

 Book of Physiology "), acts upon the cen- 

 tral nervous system as a narcotic poison. 

 The brain forms keratin during functional 

 activity. Now, since one product of mus- 

 cular action is a narcotic poison, and an- 

 other is a waste product of the brain, it is 

 inconceivable how the blood is purified and 

 better fitted to nourish the brain. 



If, as Professor Foster says, "the fa- 

 tigue of which, after prolonged and un- 

 usual exertion, we are conscious in our own 

 bodies arises chiefly from an exhaustion 

 of the central nervous system concerned in 

 the production of voluntary impulses," then 

 Professor Richards's statement, that the time 

 for exercise is when the brain is tired and 

 one feels inclined to rest and to forego ex- 

 ercise, is open to question. May it not be 

 that the indisposition to take active exercise 

 when fatigued by brain-work is rather con- 

 servative, just as is the natural tendency to 

 rest after a full meal during the process of 

 digestion ? Respectfully, 



A. B. ROSENBERRY, M. D. 



Sheboygan Falls, Wisconsin, July 8, 1886. 



A CUEIOU3 OPTICAL PHENOMENON. 

 Messrs. Editors : 



A strange phenomenon was observed 

 here at a few minutes before sunset yester- 

 day evening. A heavy storm had come up 



