THE LAWS OF ENERGETIC EXPENDITURE 171 



made the arm work so as to lift different weights, at variable 

 heights and speeds, each lift being followed by a rest. 



1. Study of D e .~ Increased weights can be sustained by con- 

 tracting the flexor muscles 13 times a minute. No work is pro- 

 duced and it is found : 



kg. kg. 

 1-5 3 



cu. cm. cu.cm. 

 40 79 



Weight sustained. 



Expenditure of oxygen 



kg- 

 4-5 



cu. cm. 

 133 



kg. 

 6 



cu. cm. 

 197 



The effort of support is more onerous if the number of con- 

 tractions or, what is identical, the number of excitations furnished 

 by the nerves is increased. Thus : 



Contractions 



Expend, of oxygen 

 for 



This result is very interesting, as it shows that the frequent 

 starts and stops increase the expenditure. One cannot, there- 

 fore, ignore the fact that the action of the nerve on the muscle 

 necessitates a certain consumption of energy and the greater the 

 effort to be produced, the greater will be that consumption. The 

 expenditure of energy in setting in motion heavy weights is thus 

 shown in another aspect. 



2. Study of Ph -f- V. This is the work itself, work estimated 

 in quantity (Ph) and in quality (V). Chauveau varied Ph, 

 leaving h constant, at 442 m. and also the speed, whilst P was 

 varied from^l-5 to 6 kilogrammes. 



By 13 contractions in 1 minute, the weight was lifted to 4-42 

 metres, i.e., 0-34 metres per contraction of the flexor muscles. 

 Under these conditions, the expenditure D</ was measured and 

 knowing D e , Ph -f- V can be found. 



The variations of Ph + V are less rapid than those of the weight 

 lifted, while D<* varies more or less in proportion to the weight. 

 Hence the static effort D, is most felt in the expenditure. 



