76 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING. 



table 11) and after the heavy noon meal 1.45 calories. There was, 

 therefore, an average increment of approximately 0.2 calorie or 16 per 

 cent, due to the ingestion of the food. This value is strikingly in agree- 

 ment with that found with subject I, and we may accordingly state 

 that the basal metabolism of both subjects used in the research was 

 increased approximately 16 per cent by the ingestion of the kinds and 

 amounts of food consumed. This has an important bearing upon the 

 subsequent calculations, for it is obviously impossible to make an intelli- 

 gent comparison of the standing values obtained with individuals in the 

 post-absorptive condition with those obtained after the ingestion of food. 

 Finally, it should not be forgotten that a part, at least, of the incre- 

 ment ascribed here to the ingestion of food, particularly after the noon 

 meal, may be due to a slight after-effect of the muscular activity of 

 walking in the forenoon experimental periods. On the other hand, 

 there is such a close agreement between the increment in the metabolism 

 after the light meal, which was invariably taken before the morning 

 walking periods, and the increment in the metabolism after the midday 

 meal, that it would imply that the influence of the morning work must 

 have been extremely small. 



METABOLISM DURING WALKING. 



The preliminary study of the mechanics of position incidental to 

 walking was obviously only for the purpose of throwing light upon the 

 various mechanical processes involved in walking and the metabolism 

 essential thereto. The primary purpose of the research was to study 

 the actual metabolism during the motion of forward progression. 



WALKING EXPERIMENTS WITH SUBJECT I. 



The first series of walking experiments was made by Dr. Tigerstedt 

 with subject I in the month of December 1913. These experiments 

 were all carried out under practically the same conditions, that is, 

 following two or three periods when the subject stood in a relaxed 

 position during which time the basal standing metabolism was meas- 

 ured. The body-weight of the subject was a practically constant 

 factor, as it did not alter materially throughout the month. An 

 attempt was made to maintain an essentially constant speed of the 

 treadmill, the rate averaging not far from 76 meters per minute. In a 

 few of the experiments, the speed was lowered to about 65 meters per 

 minute, but in no instance did it exceed 80 meters per minute. Under 

 these conditions we may consider that the study was based upon a 

 constant speed and that accordingly all values are strictly comparable 

 so far as the velocity is concerned. The walking experiments con- 

 sisted of two or three and occasionally four periods per day. On two 

 days walking experiments were made after the ingestion of food. 



