The average values found with Squad A and the average normal for Squad B can best be summarized in connection with a review of the comparisons with Squad B before and after reduced diet. These comparisons are made in table 143.

For the reasons given previously, we believe the values for Squad B normal may be properly assumed to represent the values for Squad A normal, and the computations are thus made in table 143. The distance walked remained the same in all tests. The body-weight in all tests decreased. The total heat output required to walk 10 km. decreased with the 12 men of Squad B 14.8 per cent. With the 11 men of Squad A, whose period of reduced diet was much longer with a much greater loss of body-weight, it decreased 22.7 per cent. This decrease represents in both cases a pronounced fall in the total energy requirement for the transportation of the individual over a given distance.

Table 143. - Comparison Of The Metabolism Of Squads A And B On Reduced Diet With Squad B Normal For A Basis

1 Average of 11 subjects.

It thus appears that the demonstrated decrease in the metabolism of these individuals, when resting quietly, and when standing quietly, is also noted in walking, and that the organism can walk at much less expenditure of energy with low diet. This, of itself is an extremely important practical point. From earlier experiments of Durig and his school, who have studied the effect of superimposed loads, one may reasonably assume that with the reduced diet the individual can not only walk a given distance, but can transport a load equivalent to the loss in body-weight at no greater expenditure of energy than was noted prior to the diet reduction. In this sense there would be a distinct economic gain, for each kilogram of body-weight lost may now be transported in the form of effective external load and the total energy requirement or expenditure not exceed that prior to restriction.

When one considers the organism as a system of levers and attachments for performing muscular work, and that during the process of weight reduction these levers have decreased in weight with, in consequence, a lessened demand for energy for their movement, it can be seen that the lighter the member, other things being equal, the more effective the mechanical operation.

Of special significance, however, is a consideration of the values for the heat output per horizontal kilogrammeter, i. e., for the same unit of work. As previously pointed out, with Squad B there was a slight decrease in this factor, indicating an increased efficiency. A change in this factor is of such great physiological importance that it is only with considerable reserve that one should draw deductions from it. Remembering that the normal data with Squad B on January 6 had a wide variation and that Squad A on reduced diet have no normal values obtained with them directly for use in such comparison, and that the normal values for Squad B must therefore be employed, it may be considered unjustifiable to draw a definite conclusion that the subjects walked at a greater efficiency on a reduced diet than under normal conditions. Nevertheless, the figure of 6 per cent with Squad B is substantiated, at least to a reasonable extent, by the figure of 12.6 per cent with Squad A. It is thus probable that there is a distinct increase in efficiency, even when considering the activity from the standpoint of per unit of work accomplished.

While a larger group of subjects would be desirable, it is believed that the number of men studied is sufficiently large to average most of the individual variations. The three sets of experiments were made in exact duplicates and the conditions of the series were similar. The results from the three series may therefore be taken as contributory to the whole picture. In considering these results it should be remembered that in this test the influence of practice was reduced to an almost negligible quantity. Every muscle employed in treadmill walking was employed a hundred fold over in the daily routine of each man. The rate of walking was purposely made moderate to eliminate the question of excessive work, and the periods were brief enough to eliminate the question of fatigue.

While we believe that the conclusions regarding these experiments show unquestionably an actual saving in energy for the transportation of the body of the individual over a stated distance and distinctly imply, also, that each unit of work is accomplished with a somewhat higher degree of efficiency, the important relationship between this type of work and muscular activities in general should here be emphasized. Walking is a practiced effort. The experiments were planned for tests with moderate exercise of a well-established and practiced character. But in consideration of the fact that not only is there an absolute total saving in energy, but a probability of a slight saving per unit of work, we have every reason to believe that similar increases in efficiency, both total and relative, would be shown with other forms of exercise including, indeed, industrial operations, if the influence of fatigue and excessive work were eliminated. On these two latter points these experiments do not give and were not planned to give any evidence. Whether the men would show equal efficiency in prolonged walking or heavy-grade walking on a reduced diet as on a normal diet is a question for further study. But the conclusion seems clear to us that these results show that the men of both Squads A and B - Squad A at a maintenance period and Squad B while undergoing a rigid diet reduction - walked with a saving in total energy expended and with a somewhat greater efficiency per unit of work than did Squad B on a normal diet.