PHYSIOLOGICAL EFFECTS OF GRADE WALKING. 263 



The high pulse-rate of H. R. R. in most of the standing and hori- 

 zontal-walking experiments persists, also, in the grade experiments, in 

 which a rate of 140 was found with the subject walking on a 10 per cent 

 grade at a speed of 60 to 65 meters per minute (about 2.5 miles an hour), 

 as compared with a rate of 125 and 103 for W. K. and E. D. B., re- 

 spectively, under similar conditions. (See table 56.) 



T. H. H. shows the exceptional behavior of a falling pulse with in- 

 crease in the speed for the single grade used in his experiments. This 

 is due, in part, to the considerable number of periods on April 6 and 7, 

 when all of the period data for the lowest speed (55 to 60 meters per 

 minute) were obtained. Out of the 9 periods composing the average 

 for a speed of 55 to 60 meters a minute, the 3 highest were the last 

 records of a continuous forenoon performance on April 7 of 6 periods. 

 The average pulse-rate for this speed was therefore high on account of 

 the cumulative effect of the work on these days. However, this will 

 not entirely account for the fact that this subject had a decreasing pulse- 

 rate with increasing work. On April 15, when he performed his largest 

 amount of work, his pulse-rate was distinctly lower than on the pre- 

 vious days. A week intervened between this experiment and the pre- 

 ceding one, but we have no record that his physical condition was 

 different in this experiment from that in any other. Evidently the 

 experiments with T. H. H. were not continued long enough to deter- 

 mine his representative pulse-rate in the performance of a moderate 

 amount of exercise. 



W. K. and E. D. B. offer more data for comparison. These values 

 indicate that, with occasional exceptions, the pulse-rate progressed 

 with the speed for each grade. The increase in the pulse-rate in rela- 

 tion to the amount of work performed is depicted in the curves for 

 these subjects in figures 28 and 29, x which are based upon the averages 

 in table 56. They indicate a practically uniform increase with increase 

 in the amount of work done. The curve for W. K. ascends more 

 sharply than that for E. D. B., the average pulse-rate increasing from 

 1 15 to 176 beats for an increase from 298 to 891 kg. m., or approximately 

 one beat for every 9.7 kg. m. increase in work, while the average pulse- 

 rate of E. D. B. increased from 84 to 186 beats for an increase in work 

 from 59 to 1,569 kg. m., or an increase of one beat for every 14.8 kg. m. 

 increase in work. If these values are referred to the average basal value 

 found in the standing experiments (79 for W. K. and 78 for E. D. B.), 

 the increase for the maximum amount of work is found to ba 123 per 

 cent for 891 kg. m. with W. K. and 138 per cent for 1,569 kg. m. with 

 E. D. B. This would correspond to an increase of approximately 

 7 kg. m. for every 1 per cent of increase in the pulse-rate for W. K. and 

 11 kg. m. for E. D. B. 



'All of the curves in these two figures represent averages of estimates drawn independently 

 by three members of the Laboratory staff. 



