WORK PRODUCTION 



559 



665. Influence of load. With the horse, Zuntz and Hage- 

 mann find that carrying a load on the back causes a distinct 

 increase in the net expenditure for horizontal locomotion per 

 unit of mass moved. The work of ascent, on the contrary, 

 was performed with at least as high an efficiency by an animal 

 carrying a weight as by one without load. With man, Bene- 

 dict and Cathcart find the net efficiency but little affected by the 

 amount of resistance in their bicycle ergometer. Brezina and 

 Reichel find that at moderate speeds the load carried by a man 

 affects but slightly the net expenditure per kilogram and meter 

 distance but that above the point at which the speed begins 

 to affect the latter, the increase is greater as the load is increased. 



666. Influence of grade. The net efficiency with which 

 work of ascent is done decreases as the grade is made steeper. 

 Zuntz and Hagemann in their experiments upon the horse ob- 

 served a decrease of the efficiency from 34.3 per cent to 33.7 per 

 cent as the grade was increased from 10.7 per cent to 18.1 per 

 cent, while for work of draft the efficiency was 31.3 per cent on a 

 0.5 per cent grade but only 22.7 per cent on an 8.5 per cent grade. 



That the same is true in the case of man is illustrated in experi- 

 ments by Loewy, who obtained the following results on three 

 different individuals. 



TABLE 157. INFLUENCE OF GRADE ON NET EFFICIENCY IN WORK 

 PRODUCTION 



The same conclusion was reached in the recent investigations 

 of Brezina and his associates 1 on man. From an extensive 

 series of experiments they compute the net efficiency to have 

 been approximately : 



1 Biochem. Ztschr., 63 (1914), 170; 65 (1914), 16. 



