EXPERIMENTS WITH HORIZONTAL WALKING. 



151 



wholly confined to that for the muscular effort of the lower limbs, while 

 the oscillations of the trunk in keeping the body balance play a minor 

 role. This finds confirmation in some experiments reported by Waller 1 

 on the carbon-dioxide production during horizontal walking. In a graph 

 showing the carbon-dioxide output for different rates of walking, he 

 also includes that for marking time at a rate of 120 steps per minute. 

 He does not discuss this portion of the curve, and it is probable that 

 the form of marking time was different from that which we used. 

 However, the carbon-dioxide output indicated by his curve seems to 



TABLE 40. Metabolism of W. K. while "marking time 1 ' in experiments without food. (Values per minute). 



'See table 27 (page 111) for additional records for pulse-rate of W. K. while he was "marking time." 



be very close to the requirement of the subject when walking at a 

 speed of 92 meters per minute, or 130 steps per minute, viz, an output 

 of 972 c. c. of carbon dioxide for marking time and 960 c. c. for walk- 

 ing. That is, the carbon-dioxide requirement for marking time at 120 

 steps and walking at 130 steps differed only by 1 per cent. 



In their study with army recruits, Cathcart and Orr 2 included obser- 

 vations of the respiratory exchange with a subject ''marking time." 

 In 10 experiments after meals of varying composition and with the 

 man carrying loads varying from 5 to 20 kg., the total heat-output 

 varied from 209 to 271 calories per hour. The standing value was 

 about 75 calories per hour. 3 The tempo was 100 beats per minute. 



taller, Journ. Physiol., 1919, 53, Proc. Physiol. Soc., p. xxiv. 

 'Cathcart and Orr, Energy expenditure of the infantry recruit in training. 

 Office, London, 1919. (See table 47.) 



8 See subject M, tables 7 and 8 of Cathcart and Orr, lac. cit. 



H. M. Stationery 



