306 



Scientific Proceedings (116). 



158 (1740) 



The lactic acid in the blood of dogs in exercise. 



By A. BAIRD HASTINGS. 



[From the Department of Physiology, Columbia 

 University, New York.] 



In the course of our study of fatigue, it became desirable to 

 make determinations of the concentration of lactic acid in the 

 blood. Ryffers method was used with the modification that the 

 formaldehyde standard was tested against a known lactic acid solu- 

 tion in each experiment. The blood was obtained from the 

 jugular vein of dogs which were exercised on a motor-driven 

 treadmill. The results of typical experiments are given in Tables 

 I and II. 



It will be seen from Table I that severe exercise of short dura- 

 tion brought about a marked increase in the concentration of the 

 lactic acid in the blood. The results given in Table II, however, 

 show that when the exercise was of moderate intensity and long 

 continued, the concentration of lactic acid in the blood was de- 

 creased. We believe that the increase of the lactic acid in the 

 blood in the initial stages of severe exercise may be associated 

 with the hyperpnea occurring at that time, and that its subse- 

 quent decrease, due perhaps to an increased efficiency of the oxida- 

 tive processes, may be related to "second wind." In view of the 

 fact that no increase has been found in the lactic acid in exercise 

 however long continued, its significance as a primary factor in 

 physiological fatigue, not carried to exhaustion, would seem open 

 to question. 



Table I. 



The Effect of Severe Exercise of Short Duration on the Concentration 

 of Lactic Acid in the Blood of Dogs. 



Dog. 



Date. 



Distance 

 in 

 Miles. 



Rate 

 in 



Miles/hr. 



Lactic Acid in 



Before 

 Exercise. 



Mgm./ioo ex. 



After 

 Exercise. 



a. . . : . . 



B 



C 



March 10, 1921 



February 9, 1921 



March 16, 192 1 



0.28 

 0.24 

 0.23 



9-3 

 8.0 

 7.7 



5-3 

 12.4 

 IX.7 



17-3 

 19.9 

 55-3 



