164 METABOLISM DURING WALKING. 



it has been the practice to record carefully the pulse-rates in all the 

 basal metabolism measurements carried out here. Such records were 

 accordingly made in this research. 



The detailed data of the pulse-rates of the subjects during the hori- 

 zontal walking periods, as obtained by the method already described, 

 are given chronologically in tables 8 to 12. It should be stated again, 

 however, that the difficulties which were experienced in this initial 

 work of recording the pulse-rate have made the data incomplete. 

 Accordingly, although the rates as reported for the individual periods 

 are, in a large majority of cases, average values determined at three 

 intervals about equally distributed throughout the period, nevertheless, 

 there are individual averages which represent only one or two readings. 



As the pulse-rates tended to increase during the walking periods, 

 the average value would naturally be affected by the failure to secure 

 either the first or the last reading, and this fact undoubtedly explains 

 some of the irregularities. Although many measurements of the 

 pulse-rate have been made in connection with studies on muscular 

 exercise, the difficulties of actually recording the pulse by the methods 

 commonly used are great when the subject is exercising, and most of 

 the records previously reported have therefore been made immediately 

 at the end of and not during the period of exercise. 1 



As the pulse-rate is subject to sudden and wide fluctuations due to 

 mental and physical conditions, uniformity in results is perhaps more 

 than should be expected, and only comparisons from much larger 

 groups of results than here obtained could yield very definite conclu- 

 sions. For this reason the speed groups in table 35 and the summary 

 in table 44 give, perhaps, the most satisfactory method for comparing 

 the material at hand. However, the results recorded in tables 8 to 12 

 show one point very clearly, namely, that the pulse-rates tended to 

 increase as the periods continued during the forenoon. 



From both tables 35 and 44 it may be seen that H. R. R. had a 

 high pulse-rate as compared with other men walking at similar speeds. 

 With this subject the highest pulse-rate and highest metabolism were 

 obtained on his first day of walking. (See table 8, p. 56.) The two 

 averages for H. R. R. in tables 35 and 44 show that his pulse-rate was 

 increased 6 beats for an average increase in speed of 6.2 meters per min- 

 ute. T. H. H., however, shows the reverse, although the average for 

 the heat-output increased. (See table 35.) W. K. had an increase in 

 pulse-rate between the first and second speed-groups, but a drop of 

 1 beat between the second and third groups. These figures of W. K. 

 do not cover the earlier days of his walking experiments, while the 



1 A striking exception is that too little known but admirable research of W. P. Bowen (Bowen, 

 A study of the pulse-rate in man as modified by muscular work. Contributions to Medical 

 Research, dedicated to Victor Clarence Vaughan by colleagues and former students of the De- 

 partment of Medicine and Surgery of the University of Michigan, Ann Arbor, Michigan, June, 

 1903, p. 462.) 



