170 



METABOLISM DURING WALKING. 



tilation are linear functions, and Means and Newburgh 1 have shown 

 that the same is true for the oxygen consumption and ventilation in 

 relation to work. 



In figure 13 curves have been plotted for E. D. B. for the total heat- 

 output, oxygen consumption, pulmonary ventilation, respiration, and 

 pulse-rate in relation to the horizontal kilogrammeters (h. kg. m.) 

 of work done, using the average values for the 5-meter speed-groups 

 in table 35, page 144. These curves show how closely the heat-output 

 and the oxygen consumption follow each other with the increasing 

 amount of work done. They also show a constant rate of oxygen con- 

 sumption up to the point of 2,720 h. kg. m. Above this the oxygen 

 increases at a uniform rate with the work done, if we except the h igh point 

 of 3,840 h. kg. m., which represents the work done for the most part in 

 October when the experiments were begun with this subject, and he 

 was unused to the apparatus. The curve above 4,560 h. kg. m. is 

 somewhat more sharply ascendant than below that point, but there is 

 no marked alteration in the oxygen consumption. 



P R V 



Liters 

 100 22 



H. Kgms. 2400 



2800 



3200 



3600 



4000 



4400 



4800 5200 



5600 



400 2.0 



6000 



FIG. 13. Total heat-output (cals.), oxygen consumption (O 2 ), pulmonary ventilation (V), 

 respiration-rate (R), and pulse-rate (P), of E. D. B. and W. K., referred to horizontal kilo- 

 grammeters (h. kg. m.) for experiments with subjects walking on a level at different speeds. 

 (Values per minute.) 



The supply of oxygen necessary to meet the increased needs of the 

 body during work is determined by a number of factors, of which pul- 

 monary ventilation and pulse are of special importance. The pulse 

 and ventilation curves should therefore be compared in relation to the 

 oxygen consumption. Like the curve for oxygen, the two curves for 

 pulse-rate and ventilation show no notable changes with the smaller 

 amounts of work. For the larger amounts the increase in the oxygen 

 consumption is followed more closely by the pulse-curve than by the 

 ventilation curve, as the latter does not increase, but remains practi- 

 cally uniform between 3,400 and 4,300 h. kg. m. This would indicate 

 that the necessary oxygen for the increased needs of the body is met 



J Means and Newburgh, Journ. Pharm. and Exp. Therapeutics, 1915, 7, p. 449. 



