208 THE HUMAN MOTOR 



subject^ 1 ) Hence after a prolonged period of work the ergo- 

 graphic curve falls rapidly. If we make use of the curve to esti- 

 mate the degree of fatigue, it is important to remember that due 

 allowance must be made for the effect of pain 01 discomfort. ( 2 ) 

 Thus a very intense effort can provoke muscular or nervous pain, 

 so that the curve may show pronounced fatigue before any con- 

 siderable amount of work has been done. 



Furthermore, in some. occupations the fatigue is localised in 

 a single limb, the arm, leg, or fingers. If so, the curve can only 

 show a simple local fatigue. However, the ultimate effect is 

 general, and the fatigue spreads to several muscular groups 

 slowly and progressively. 



" The muscles of the forearm tire the most rapidly, and give a 

 lesser quantity of mechanical work as the result of the general 

 fatigue produced by a walk of 10 kilometres." ( 3 ) 



The secret of attaining the maximum yield from a workman is 

 to proportion the elements of the work so that the muscles con- 

 tract without pain or excess of local fatigue. 



Ergograms reveal also, by their shapes and the quantities of 

 work they represent, the influence of the numerous factors] of 

 human activity : the nature of this or that food, external 

 temperature, position of the body, the magnitude of the effort to 

 be produced, speed of walking, and the rhythm of the movements. 

 By their means ( 120) the speed of economical work and, to some 

 extent, of muscular indefatigability, can be determined, of which 

 the heart offers a curious example. 



An ingenious observation of Galileo ( 4 ) may be quoted (1564- 

 1642) : " The fatigue of the body of an animal depends, according 

 to my idea, on the fact that he uses one of his parts to move the 

 whole ; you will find, on the other hand, that the heart is inde- 

 fatigable, because it only moves itself." 



In feats of strength, such as wrestling, accidents are frequent : 

 fractures, dislocations and abrasions ; hence the need for great 

 resistance, so that the man only yields to fatigue. * If, on the 

 contrary, the man has organic defects, an accident will soon limit 

 his activity, and he stops working without being as yet fatigued. 

 The state of the heart and the lungs also contributes to the exertion 

 of force, and the flow of blood and the respiratory flow are in pro- 

 portion to the effort. The man capable of a great display of 

 muscular force is characteristed by the following features : 



(*) Grandis (Arch, per le Science Medicihe, vol. xxvi., p. 269, 1902). 

 ( 2 ) Pain is often the result of bad tools and a lack of workmanlike ability. 

 () A. Maggiora (loc. cit., p. 217). 

 ( 4 ) Galileo Opere, Milan Edn., 1811, vol. xi., p. 558. 



