152 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



The method in the present research and in some previous unpub- 

 Hshed studies is clear from an inspection of figures 22 and 23. The 

 subject, connected to the string galvanometer, recUned comfortably in 

 a steamer chair. Above him and within easy reach was suspended a 

 bar of suitable dimensions, which was easily capable of bearing the 

 subject's weight. At a given signal he grasped the bar and raised him- 

 self to the position in figure 23, with his weight entirely free from other 

 support. He remained in this position for a period of 5 seconds and 

 then quickly settled back into the chair and into as complete relaxation 

 as possible. The exertion produced in this way is more uniform than 

 when the subject stiffens his muscles but remains seated. The bar is 

 placed at such a height that, in order to keep the body free from other 

 support, it is necessary to thrust the feet forward and hold them up. 

 This causes muscular tension in abdomen and legs. Thus the whole 

 body is exercised and it is rather unlikely that a subject would find it 

 possible to learn to isolate the muscles most used and to keep the others 

 well relaxed. 



The photographic pulse tracing (electrocardiogram) was continuous 

 for about 8 seconds of rest preceding exertion, during the period of 

 exertion, and for 20 to 30 seconds following the exertion. Sample rec- 

 ords are reproduced in figure 24. It should be noted that these records 

 are made primarily to record heart rates. They are not standard 

 electrocardiograms for three reasons : (1) The deflection of the string of 

 the galvanometer is not standardized, for the string is made taut in 

 order to reduce the large deflection caused by the swift and general 

 body movements. (2) Electrical condensers are placed in series with the 

 string and the subject; in this case 12 microfarads were used. These 

 condensers serve to minimize deflections in the base-line, that is, to 

 cut out or reduce all slow changes in potential, such as those occasioned 

 by movement of the arms and trunk of the subject. This causes, of 

 course, a reduction in the size of the P and T waves of the common 

 electrocardiographic complex. (3) The points of leading off from the 

 subject's body, that is, directly below the arms, while corresponding 

 fairly well to Einthoven's lead No. 1 {LI), are not exactly the same as 

 this or any other commonly used lead. 



Figure 24 shows records for three subjects. In the illustration it has 

 been necessary to cut each record in two. Thus, A' must be considered 

 as belonging at the right hand end of A, and together they form one 

 continuous record. The same appUes to B and B' and C and C . The 

 three sections of a record are clearly marked : At the left is a short sec- 

 tion covering 6 or more pulse cycles representing a period of rest before 

 the exertion (the paper may be regarded as having moved from right to 

 left when the record was being taken). Near the center is the section 

 of the pulse record taken during the moments when the subject was 

 supporting his weight on the bar. The string is seen to have been dis- 



