DISCUSSION OF RESULTS. 81 



73.1 kilograms, this would correspond to a work equivalent of 276.32 

 kilogrammeters or 0.65 large calorie per minute. Since the total 

 increase over the standing metabolism due to walking averaged 2.81 

 large calories per minute, it is seen that approximately 23 per cent of the 

 energy required for the work of forward progression was employed in 

 raising the body in a vertical direction. 



These experiments give no data regarding the amount of energy 

 required to lower the body after being raised at each step. Various 

 assumptions are found for this in the literature, ranging from one- 

 quarter to three-quarters of the work done in the elevation of the body, 

 but it is obviously out of place to attempt such gross interpretations 

 of the results. 



In conclusion, then, we may say that when walking in a horizontal 

 direction at the rate of 76 meters per minute, a man with a body-weight of 

 73 kilograms produces 2.81 calories per minute above his standing basal 

 metabolism, of which 0.65 calorie or 23 per cent is required to raise the 

 body through a distance of approximately 4 meters per minute. It is 

 thus apparent at the outset that a very important factor in the energy 

 consumption while walking in a horizontal direction may be the type of 

 step employed. Unfortunately our observations were not made upon a 

 sufficient number of persons to permit a complete discussion of this point. 



WALKING EXPERIMENTS WITH SUBJECT II. 



Subject II, who was a professional athlete, though not in continuous 

 training, had exercised excessively in bicycle riding and had been the 

 subject in Cathcart's research on the muscular work of bicycle riding. 

 He had done a considerable amount of walking when in training, but 

 was not an especially well-trained walker and certainly could not be 

 classed as a professional pedestrian. On the other hand, he performed 

 all of the tests on the treadmill at even the highest speeds with perfect 

 ease and was at no time unduly distressed. 



The walking experiments with this subject covered a period of 

 approximately two months, i. e., from March 16 to May 15, 1914. 

 About 40 per cent of the experiments were made without food; the 

 remainder of the experiments followed either the breakfast or the mid- 

 day meal, the diet in some cases being controlled. The speed of rota- 

 tion of the treadmill varied during the experiments without food from 

 56.0 meters per minute to 146.8 meters per minute and in a few experi- 

 ments, with the subject running, it increased to 148.7 meters per 

 minute. The greater part of the experiments were made with a speed 

 between 56.0 and 93.3 meters per minute. 



In computing the energy per horizontal kilogrammeter, we have the 

 same problem to consider that was met with in the case of subject I, 

 namely, the selection of a suitable base-line. As the tests with sub- 

 ject II were more varied than those with the first subject, at least 



