PHYSIOLOGICAL EFFECTS OF LABOUR 203 



In climbing a slope of 11-50 cm., rise in 80 metres, the pulse, 

 originally beating at 70, the successive results were : 



96 106 112 



an increase of 



26 36 42 



The duration of 

 the walk was 40 33 30 seconds. 



which verifies the preceding relation between these quantities, 

 and also shows the effect of the slope of the ground and the speed. 

 The increase in the pulse for the same duration of 30 seconds was 

 42 instead of 9. 



Finally, the systolic phase is prolonged during heavy work, 



and the relation * diminishes gradually, the dicrotism 



systole 



becomes less, but the arterial pressure, on the contrary, in- 

 creases. If, however, the exercise is violent, the pressure 

 becomes considerably less. During the performance of work 

 on a bicycle, amounting to 10,000 kilogrammetres in 10 minutes 

 the arterial pressure increased by 30% measured by the Pachon 

 method. 



All these elements taken together indicate the degree of fatigue. 

 Lavoisier was the first to draw attention to a remarkable relation 

 between the quantity of work done and the number of respira- 

 tions and of pulsations. According to this illustrious scientist 

 " the first quantity is proportional to the product of the other 

 two. " (*) Nevertheless this observation cannot be strictly applied. 

 It is only true when the work progresses quietly and produces no 

 fatigue. It is fairly correct for moderate degrees of activity. 



144. Effects of Work on the Muscular Power. It is a fact of 

 common observation that normal work " trains " (entraine) the 

 muscles, provoking a greater irritability of their fibres ( 138) 

 and reducing, perhaps, the period of getting into action which 

 shows itself in beginners by the stiffness of their movements. 



Before a detailed examination of the nature of muscular 

 " training " (entrainement) it must be pointed out that, according 

 to various authorities, it is accompanied by a gain of force. Thus, 

 if the arms are woiked until fatigue ensues, lifting dumb bells of 

 5 kilogrammes each above the head, at the beginning five move- 

 ments can be made in four seconds, but gradually this number 

 can be increased up to 120 movements. ( 2 ) 



(*) Lavoisier, GLuvves Completes, vol. ii., p. 696 (edition officielle). 



( 2 ) G. Manca (Arch. Ital. Biol., vol. xvii., p. 390) ; Henry (Comptes 

 Rendus Sciences, vol. cxii., p. 1473) ; W.-C Lombard (Journal of PhysioL, 

 vol. xiii., p. 1, 1892). 



