418 VITALITY AND EFFICIENCY WITH RESTRICTED DIET. 



in the case of this individual the given amount of exercise required a 

 pulse-rate of about a certain level, and that in the case of the lower 

 resting rate the tone of the vagus is higher or is somewhat more affected 

 at the time of the exercise. 



Different subjects show, naturally, individual peculiarities in their 

 curves for changes in pulse-cycle length during and following the short 

 periods of exertion but, in general, the pulse-cycle length required for 

 the exercise tends with any individual to be a constant, no matter what 

 the resting level may be.^ 



It is rather difficult to place the data for these pulse changes in 

 quantitative terms for comparison. An effort in this direction is 

 made in tables 94 and 95 for Squads A and B, respectively. The three 

 figures given for any subject and date represent the average pulse-cycle 

 length in 0.01 second in the three different portions of the record. For 

 example, with Bro on October 28, 0.92" is the average pulse-cycle 

 length of the 6 pulse cycles in the portion of the record which preceded 

 the beginning of activity, 0.66" is the average for all of the pulse cycles 

 which came within the limits of the activity, and 0.67" the average of 

 the 20 pulse cycles which followed the cessation of activity. (See 

 table 94.) With each subject these same conditions for the averages 

 apply. All the members of Squad A, excluding Kon and Spe,"^ show 

 averages for October 28 of 103 for the period of quiet, 75 for the period 

 of activity, and 79 for the first 20 pulse cycles in recuperation following 

 activity. Assuming the duration of pulse cycles during "quiet" as a 

 basis for calculation, we have for activity and rest 72.8 and 76.6 per 

 cent, respectively, as shown in the extreme right-hand column of the 

 table. Therefore the average cycle-length during the period of activity 

 was 27.2 per cent shorter than during the quiet, and in the 20 beats 

 following the activity it was still on the average 23.4 per cent shorter 

 than during the period of quiet.^ 



The low diet average for Squad A for the 5 dates, October 28, 

 November 11, December 9, January 13, and January 27, and for the 

 10 men whose records were averaged {Kon and Spe omitted) are 109, 

 77, and 85 for quiet, activity, and rest, respectively. The activity and 

 rest are but 70.6 and 78.0 per cent of the quiet pulse-cycle length. The 

 individual subjects show an average pulse-cycle length under condi- 

 tions of quiet which ranges from 87 to 125 — Tom and Pea. Two other 

 subjects, Vea and Pec, are very close to this upper value; that is, they 



^ Miles, Carnegie Inst. Wash. Pub. No. 266, 1918, p. 102 ff.; see figs. 12, 13, and 14. This was 

 found to be the case, also, when a subject was under the influence of small amounts of alcohol. 



^ Kon came into Squad A late and Spe was ill after December. These two subjects were 

 omitted from the averages in the neuro-muscular measurements. See p. 557. 



^ While a shorter pulse-cycle length means a faster rate per minute, the quantitative statement 

 for change in the one can not be directly transferred to the other. The average cycle lengths, 

 103, 75, and 79, in terms of rate would equal 58, 80, and 76, respectively. The activity and rest 

 sections therefore show increments of 22 and 18 beats per minute over the quiet, which was 58. 

 These changes in terms of rate are 38 and 31 per cent as compared to the 27.2 and 23.4 per cent 

 for changes in cycle length. 



