6 METABOLISM DURING WALKING. 



calorie at a speed of 183 meters per minute with a load of 11 kg., and 

 from 0.48 to 0.72 gram-calorie with a load of 26 kg. The last value was, 

 however, for a speed of 110 meters per minute. They also found the 

 average cost per horizontal kilogrammeter for thrse subjects walking 

 with a 9 kg. load at speeds of 55, 82, and 110 meters per minute to be 

 0.48, 0.51, and 0.65 gram-calorie. 



Liljestrand and Stenstrom 1 report a series of respiration experiments 

 with the subjects either walking or running. These authors used the 

 Douglas bag, with the men in the post-absorptive condition. The 

 walking was done on a level track of oval form in the stadium a:. 

 Stockholm. The distances walked were 100 meters, with a preliminary 

 period of 1 minute or longer. Measurements for both the sitting and 

 standing positions were also made. The investigators report their 

 values as oxygen consumed per horizontal kilogrammeter. After 

 deducting a resting value for sitting, they assumed a respiratory quo- 

 tient and calculated for the subject N. S. (body-weight 80 kg.) an 

 average cost per horizontal kilogrammeter of 0.517 gram-calorie for 

 walking at a speed of 50 to 75 meters a minute. For a speed of 75 to 

 100 meters per minute the cost was 0.613 gram-calorie, and above 100 

 meters per minute it was 0.830 gram-calorie. For the subject G. L. 

 (body- weight, 60 kg.) the energy cost at similar speeds was 0.491, 

 0.574, and 0.710 gram-calorie, respectively. 



In their experiments with the subject running these authors found 

 that the cost per horizontal kilogrammeter fell with the increase in 

 speed. For the subject N. S., with a speed of from 144 to 175 meters 

 per minute, the heat expenditure was 1.004 gram-calories per hori- 

 zontal kilogrammeter. This fell to 0.796 gram-calorie for a speed 

 between 225 and 250 meters per minute. Similar results were 

 found with the subjects G. L. and E. S. 



Cathcart, Lothian, and Greenwood 2 have considered the energy 

 expended in relation to the velocity of walking and take exceptions 

 to the generalization of Brezina and Reichel that the cost of movement 

 remained constant up to a velocity of 80 meters per minute and there- 

 after increased geometrically. They contend that as a general physio- 

 logical law it involves a discontinuity at a fixed point between the 

 speed and the energy expenditure, and other evidence points to 

 uneconomical work at low speeds. Furthermore, as an interpolation 

 formula, they consider the data upon which it is based are insufficient, 

 for although they cover a wide range of speed and load, they relate to 

 but one subject. These authors, using the data of Brezina and Reichel, 

 show that the relation between the energy cost per unit of time and 

 speed may be represented with equally good approximations to the 



'Liljestrand and Stenstrom, Skand. Archiv f. Physiol., 1920, 39, p. 167. 

 2 Cathcart, Lothian, and Greenwood, Journ. Hoy. Army Med. Corps, April, 1920. 



