158 METABOLISM DURING WALKING. 



tables 29 to 33.) By using the factor 426.6 for the mechanical equiva- 

 lent of heat, 1 we may likewise compute the probable proportion of the 

 increment in the heat-output which was due to the work of the step- 

 lift. These percentages are given for each experiment in the last 

 column of tables 29 to 33, in which 2.34 gram-calories is taken as the 

 heat equivalent of 1 kg. m. 



Thus, by reference to table 29, we find that A. J. O., with a body- 

 weight of 75 kg. and walking at a speed of 63.1 meters per minute, 

 accomplished on February 24 in the first period 4,733 h. kg. m. per 

 minute, and by his steps lifted his body to an elevation of 1.72 meters 

 in 1 minute, thus performing 129 kg. m. of work. His standing basal 

 metabolism for this day was 1.30 calories per minute. His walking 

 metabolism for this period was 3.67 calories. The increase due to the 

 walking was therefore 2.37 calories, which is equivalent to 0.501 gram- 

 calorie per horizontal kilogrammeter, and 18.4 gram-calories per kilo- 

 grammeter of work for the step-lift. 



The values for the energy cost of this work of lifting the body (see 

 column j, tables 29 to 33) show expenditures from as high as 47 gram- 

 calories per kilogrammeter for H. R. R. to as low as 12 gram-calories for 

 E. D. B. The average cost per kilogrammeter of step-lift for A. J. O. 

 is 15.3 gram-calories, with a percentage of increment due to the 

 elevation of the body of 14 to 17 per cent. The percentage of incre- 

 ment for H. R. R. is as low as 5 per cent on his first day of walking and 

 does not exceed 8 per cent at other times. With T. H. H. the average 

 cost per kilogrammeter due to step-lift was 22.1 gram-calories, and the 

 average percentage of increment 1 1 per cent. 



The values for W. K. show considerable variation, the elevation of 

 the body ranging in the periods between 0.7 and 2.07 meters per min- 

 ute, with the amount of work done varying between 36.8 and 104.5 kilo- 

 grammeters. The least amount of work done was on March 16, and 

 these values are so much less than the other values for this subject that 

 they may fairly be questioned. The original records show nothing, 

 however, to indicate any defect in the technique to account for this 

 variance. The average heat-output per kilogrammeter due to step- 

 lift was 25.5 gram-calories, with considerable variation from day to 

 day. The daily average for the percentage of increment due to step- 

 lift ranged from 6 per cent on March 16 to 14 per cent on March 25. 

 The average for the first 6 days in March was 9 per cent and of the 

 last 6 days 10 per cent, but this difference is not sufficient to imply any 

 improvement in this respect, as these figures can at best be considered 

 as only approximate. 



'Armsby, Principles of animal nutrition, New York, 2d ed., 1906, p. 233. A so-called "best" 

 value of 426.7 is reported in the Smithsonian Physical Tables, Washington, 1920, 7th rev. ed., 

 table 212, p. 197. Our computations were made previous to the publication of this edition by 

 means of the slightly lower figure. 



