THE LAWS OF ENERGETIC EXPENDITURE 169 



T) d = 193 + 68 = 261 Calories, 

 which agrees with the measured expenditure. 



In descending the treadmill under the same conditions of speed, 

 the man spends 125 Calories and the calorimeter registers 164 

 Calories. This is written 



U = Q T or 125 = 164 68 (= 96 Calories). 



It will be seen that some heat has certainly been restored, but 

 in insufficient quantity. The experiment leaves something to 

 be desired, although the principle of the conservation of energy 

 is shown. Also the physiologist must admit some causes of 

 of error in the experiment. The energetic expenditure is shown 

 to be less in resistant work than in motor work, the muscles are 

 less heated ( x ) and the respiration is less intense. Chronophoto- 

 graphy shows a very slightly marked muscular relief (Richer). 



The smaller expenditure in resistant work is explained by the 

 fact that the muscles furnished an effort, which is less than the 

 motor effort, and do so with a view to transforming the accelerated 

 movement of the body due to gravity into a movement of 

 uniform speed. 



In a free fall, there would be no expenditure. The term V in 

 Chauveau's formula decreases as the fall becomes more rapid. 



115. Detailed Examination oJ Chauveau's Formula : Its Prac- 

 tical Results. Chauveau studied the effects of speed and effort 

 on energetic expenditure. ( 2 ) A man weighing 50 kilogrammes 

 worked a treadmill at a speed of 431 metres an hour. This con- 

 stant speed was maintained, and the subject was progressively 

 loaded by 10 kilogrammes at a time to modify the speed of 

 ascension. 



The following results per hour were obtained : 



The minimum expenditure here corresponds to a weight of 

 60 kilogrammes. When the load remained constant (50 kilo- 

 grammes) and only the speed varied : 



(*) A. Chauveau (Comptes Rendus Sciences, 1895, vol. cxxi., p. 26). 

 ( 2 ) A. Chauveau (Comptes Rendus Sciences, 1901, 1st Sept., p. 194).- 



