MECHANICAL EFFICIENCY OF THE HUMAN BODY 117 
timately became strained and uncomfortable, it was obvious that this subject 
was in a wholly abnormal condition throughout practically all of this class of 
experiments. With the subject M. A. M. no foot-rests were used, the feet 
being placed upon the pedals and allowed to remain there. With the other 
subjects, J. E. F., K. H. A., and E. P. C, a foot-rest was usually placed on 
the front of the machine or else a wooden block was placed upon the floor 
on which the feet could rest. J. E. F. also found the sitting position very 
tiresome and accompanied by strain. 
It will be seen, therefore, that there is a complete lack of harmony in 
the results obtained from experiments in which the subject changed from 
a lying to a sitting position. It was particularly unfortunate that with er- 
gometer II, with which the largest number of work experiments was made, 
the values for sitting indicate clearly that the discomfort experienced by the 
professional subject unquestionably increased his metabolism, a fact which 
must be taken into consideration when this abnormally high base-line is 
used in any way. 
Increment in Metabolism Due to a Change in Position from Lying on a Couch 
to Sitting on a Motor-driven Ergometer. 
In certain experiments, when the subject was sitting on the bicycle 
ergometer with the feet on the pedals and the body in a riding position, the 
pedals were rotated by means of an electric motor belted to the rear wheel. 
Under these conditions the legs moved up and down in the usual manner, 
but no external muscular work was performed," the legs being raised and low- 
ered by means of the electric motor; the work done, therefore, was essentially 
that of the internal friction of the leg-muscles. Five of these experiments 
were made with slightly varying rates of speed; the results are given in table 
113, together with the results for the comparison experiments made on the 
same days in which the subject lay quietly upon a couch. In one instance, 
namely, March 8, the average value for the whole experimental year was used 
for comparison, as no couch experiment preceded the motor-driven ergometer 
experiment for that day. By deducting the metabolism of the subject when 
lying upon the couch from that during the ergometer experiment, the incre- 
ment due to the muscular activity could be easily obtained. The increases 
found for the carbon dioxide and the oxygen are essentially alike, the increases 
in the oxygen consumption ranging from 162 to 207 per cent according to the 
speed. The pulse-rate increments were likewise considerable, ranging from 42 
per cent to 51 per cent. As in the series of experiments given in table 112, 
the respiration-rate showed but slight alteration. From the results of these 
experiments it will be seen that when the subject rode on an ergometer with 
the wheel rotated by a motor, the metabolism was practically 3 times that 
obtained when he lay on a couch. 
In connection with these motor-driven ergometer experiments many 
interesting observations were made regarding the muscular control of the 
subject. Throughout the entire series he objected to them, stating that it 
was hard for him to relax completely and allow his legs to swing idly and be 
rotated by the motor. From a consideration of the construction of the appa- 
ratus it can be seen that there should always be a tension on the sprocket- 
a See Berg, du Bois-Reymond and L. Zuntz for a discussion of this motion. Archiv f. Anat. u. Physiol., 
Physiol. Abth. Suppl., 1904, p. 42. 
