THE LAWS OF ENERGETIC EXPENDITURE 177 



By modifying the weight, the complete ergogram, at a rhythm 

 of 30, is: 



Load 1 2 4 8 kg. 



Work done 2-34 2-66 1-90 1-04 kgm. 



A weight of 2 kilogrammes allows a maximum daily work at 

 a rhythm of 30 and with a halt of one minute instead of half an 

 hour. Finally the rhythm is of great importance as for the same 

 load of 6 kilogrammes the daily work is 43 kilogrammetres or only 

 1 kilogrammetre according to whether the rhythm is 6 or 15. At 

 the rate of 6, work can go on almost indefinitely if the load does 

 not exceed 6 kilogrammes. 



The maximum work is, therefore, the resultant of an effort and 

 a rhythm suitable for practically continuous action. According 

 to Treves, this condition entails the minimum nervous expendi- 

 ture, the latter being regulated by the effort of the muscles, but 

 the resistance to be overcome must not necessitate too great an 

 effort^ 1 ) Also it is known that the resistance irritates the mus- 

 cular fibres as they are seen to lengthen and shorten. ( 2 ) It is then 

 that the nerves regulate the effort. The limit of load, compatible 

 with maximum work, is smaller if the muscles have already been 

 in action ; whence the tendency in work of any duration, to an 

 effort of progressively decreasing value. Fick ( 3 ) recognised 

 this, and Blix ( 4 ) showed later that a heavy load distends the 

 muscular fibre and renders it unable to produce its utmost. 



It is therefore of great practical importance always to work 

 below the limit of the effort which would have produced the 

 maximum amount of work. 



This sub-maximum ensures a certain economy of force, and 

 does not waste nervous energy by the too-frequently renewed 

 intervention of neuro-muscular excitations (see also 117 and 119). 

 But if, instead of lightening the load, it is necessary to incre ^se 

 it after a short period of work, it is sufficient to reduce the rhythm 

 of the contractions. The role of the will consists, precisely, in 

 assuring the maximum work under the law of the least fatigue. 



121. The Mechanical Maximum and the Economical Maximum. 



It is natural to deduce from the preceding experiments that the 



f 1 ) Trfcves (Arch. Ital. de Biologic, vol. xxxvi., 1901, p. 47 ; Arch, di 

 Fisiol., 1904). 



( 2 ) Von Anrep (Pfliiger's Arch., 1880, vol. xxi., p. 226) ; Blix, Skand 

 Arch. f. Physiol., 1893, vol. iv., p. 399) ; Benedicenti (Arch. Ital. de Biol., 

 vol. xxv., p. 379 ; 1896). 



( 3 ) A. Fick (PflUger's Arch., 1891, vol. 1., p. 189). 



( 4 ) Blix (Skand. Arch. f. Physiol., 1895, vol. vi., p. 240). 



