Validity of Ergo graph as Measurer of Work Capacity 19 



ment like this is great. The first performances induce a condi- 

 tion of extreme muscle soreness which shows itself chiefly in 

 reducing the height of contractions and thus causing a falling 

 off in the amount of work done. 



Analysis of Practice Effect on the Ergo graph. — There are four 

 discoverable elements entering into practice gain upon the ergo- 

 graph. The first is inurement, which has been discussed as a 

 process of hardening and toughening of the skin where it comes 

 in contact with the apparatus and of habituating the muscles to 

 the strains which the unusual effort imposes. In spite of the 

 best precautions the skin will be bruised and rubbed, and blisters 

 will form where the pressure is greatest. These injuries affect 

 the record after the first trial and continue to exert some influence 

 until the bruises are healed and callouses formed. Muscular 

 soreness and stiffness make their appearance shortly after the 

 first trial and grow more severe for several days. Under such 

 circumstances the reagent can not do his best. These conditions 

 continued throughout the first work period, which is indicated 

 by an average performance decrease for the left hand of B. and 

 for the right hand of M. In the following rest period opportu- 

 nity was given for recuperation. The condition, however, was 

 somewhat aggravated when work was resumed, as is indicated 

 by a decrease in several records. Generally speaking, . inurement 

 comes rapidly and becomes complete before any of the other 

 effects of practice upon the ergograph and is on the other hand 

 most fleeting, thus illustrating that fundamental law of biology 

 which says that which is most recently and easily acquired is 

 most likely to decay and disappear early. A suspension of prac- 

 tice for six days, as in the case of the third rest period, was suffi- 

 cient to reduce some records through the loss in inurement that 

 had already taken place. We shall see in the discussion later 

 how this has affected the growth of practice. 



The second element in the growth of practice is skill or per- 

 fection in the coordination of the movement. It is very difficult 

 to test accurately the growth in this direction. The inexperienced 

 reagent simply can not move his finger in the right manner to 

 lift the weight with any degree of regularity. There is no lack 



97 



