MECHANICAL EFFICIENCY OF THE HUMAN BODY 115 
in a rocking-chair. Such work does, however, bring the body-muscles into 
play, and theoretically, at least, forms an excellent base-line for the super- 
imposition of more severe loads; by increasing the resistance of the ergometer 
step by step, various loads may be superimposed upon this base-line and very 
satisfactory computations made from the increments in work. 
Finally, since many investigators have found that the efficiency varies 
with variations in the speed, the work may be done both at slow and at high 
speeds, all with the same resistance on the wheel. As a matter of fact, inas- 
much as for comparison experiments wide variations in speed should be em- 
ployed, with this particular form of ergometer there exists an inherent diffi- 
culty in carrying out such a study, for, as will be seen by the calibration curves, 
with wide differences in speed, there is a marked difference in the brake- 
effect at any part of the curve. Nevertheless, experiments have been made 
on this basis and the results will be subsequently discussed. 
COMPARISON OF BASAL METABOLISM IN BICYCLE ERGOMETER EXPERIMENTS. 
Increment in Metabolism Due to Changing from a Lying to a SrmNG Position. 
The influence of minor muscular movements and of changes in body- 
position on metabolism have received especial attention in the last few years. 
In a long series of experiments carried out in the laboratory of Wesleyan 
University, alterations in the body-position were studied by Benedict and 
Carpenter. Later a series of observations was carried out in the Nutrition 
Laboratory by Emmes and Riche, & who noted a definite increase in metabo- 
lism on changing the subject from a lying to a sitting position, the increase 
being less marked when the sitting body was supported by pillows or other- 
wise. In one experiment made in this laboratory and still unpublished, 
there was no measurable increase in metabolism following a change to the 
sitting position, this result being probably due to the fact that the body, 
shoulders, arms, neck, and head were thoroughly supported by pillows. 
Nevertheless, in changing the position of the subject from lying on a couch to 
sitting on the bicycle seat, it is reasonable to expect considerable increases 
in metabolism, and as the values obtained in the latter position were likely 
to be used as a base-line for the computation of the net efficiency, it seemed 
desirable to secure evidence as to the increase in metabolism incidental to 
the change in position. Accordingly, such studies were made with four of 
our subjects including one experiment with each of three subjects and several 
experiments with the fourth sub j ect . Nearly all of the observations were made 
with ergometer I. The results have been collected and presented in abstract 
in table 112, the carbon-dioxide production, oxygen consumption, and the 
pulse and respiration rates being recorded, as well as the increments in these 
factors in the form of per cent. Turning our attention particularly to the 
oxygen consumption per minute, it will be seen that in the experiments 
made with ergometer I the increments for all the subjects ranged from 6.1 
per cent to 24.8 per cent, and, indeed, with the subject M. A. M., the ranges 
are nearly as great, i. e., from 6.1 to 23.1 per cent. On the other hand, 
with the two subjects E. P. C. and K. H. A., the increments are essentially 
the same, 8.2 and 9.1. 
a Benedict and Carpenter, Carnegie Institution of Washington Publication No. 126, 1910, p. 243. 
t> Emmes and Riche, Am. Journ. Physiol., 1911, VI, p. 406. 
