240 



METABOLISM DURING WALKING. 



recorded in column o of tables 52 to 55. The standing requirements in 

 tables 3 to 7 and the increments due to walking on a level given in 

 tables 29 to 33 are used for obtaining the total requirements for these 

 two factors. The values used for deduction were either determined on 

 the same day or represent an average value, the selections being noted 

 in the footnotes to tables 52 to 55. These increments in the heat-output 

 which are due specifically to the grade have been plotted for W. K. 

 and E. D. B. for each grade on the basis of kilogrammeters of work. 

 (See figs. 25 and 26.) It is seen in these figures that the heat increment 

 is a linear function of the work done, as was the total heat (see figs. 21 

 and 22), but in these curves, with the basal and horizontal require- 

 ments eliminated, the amounts of heat produced for the same amounts 

 of work with different grades more nearly coincide and the curves as a 

 whole make a more nearly uniform and continuous grouping, thus indi- 

 cating that the heat increment is practically independent of whether 

 the given amount of work is produced by altering the rate of walking 

 or the grade. 



Cals. 

 13.tf 



12.0 

 11.0 

 10.0 

 9.0 

 8.0 

 7.0 

 6.0 

 8.0 

 4.0 

 3.0 

 2.0 



P. ct 5 

 GRADE 





r 



35-40 



10 



15 



20 



25 



30 



35 



40 



45 



FIG. 27. Average increments in heat-production due to grade- 

 lift in walking experiments with E. D. B. (Values per min- 

 ute from table 56.) 



To show the relation between the increment in the heat-output and 

 the grade and speed used in walking, the data for E. D. B. in table 56 

 have been plotted for the various speeds and grades and the curves 

 given in figure 27. It will be seen from these curves that a change in 

 speed from 35-40 meters to 75-80 meters per minute (or approximately 

 1.5 to 3 miles per hour) on a 20 per cent grade increased the heat-output 

 due to the grade walking approximately 4.5 calories, while a change 

 from a 5 per cent grade to a 20 per cent grade increased this factor 



