4 MUSCULAR WORK 
A study of the mechanical efficiency of a steam-engine, an internal- 
combustion engine, or an electric motor is relatively simple, since conditions 
can be arbitrarily controlled and the output measured most accurately. On 
the other hand, with a mechanism as complicated as that of the human body, 
the exact measurement of the output of muscular work is very difficult and 
not readily controlled. Consequently, studies on the efficiency of the human 
body as a machine are impracticable in most physiological laboratories. 
Furthermore, the measurement of the income and the actual fuel consump- 
tion is greatly complicated by the fact that the human body can draw upon 
a reserve of its own material, while the supply of potential energy for the 
steam-engine, the internal-combustion engine, or the electric motor is deter- 
mined solely by the actual amount delivered to it either through the steam- 
pipe, the gasoline or gas pipe, or electrical wires. But if it were possible 
to study the body-changes induced by a long course of training, to determine 
what changes take place, and why the body is more capable of extreme mus- 
cular activity, it would be logical and possible to lead up to a most rational 
method for producing this end and to explain the diversity in the training 
systems; the best features of the different systems could then be combined. 
The results of such studies would have a practical value not only for 
athletes, but for those who are accomplishing large amounts of work. It is 
of vital importance to the contractor, to the railroad constructor, and to 
other large employers of labor, that their human machinery as well as their 
mechanical appliances work to the highest degree of perfection. They 
spend large sums of money in designing, repairing, and altering the most 
complicated machinery, but until recently no attempt has been made to in- 
crease the efficiency of the large number of workmen that they must neces- 
sarily employ. With the advent of scientific management, we see the dawn 
of a new era in muscular work and its relationship to large manufacturing 
and construction enterprises. Scientific management will, however, always 
fail in its purpose unless it is based upon a scientific foundation, and as yet 
there is a great paucity of physiological data on which to base such manage- 
ment of the human machine. That any one, or two, or a dozen series of in- 
vestigations will completely revolutionize the methods of training, the dietary 
habits, or the hygienic conditions of a group of workmen is hardly to be ex- 
pected. On the other hand, a carefully worked-out series of experiments for 
studying the mechanical efficiency of the human body, the relationship between 
muscular work and the total energy intake and output, the character of metab- 
olism in the body as affected by muscular work, the problem of training as 
affecting the body-composition, and the relative readiness with which the differ- 
ent stores of material in the body can be drawn upon for fuel, will, if properly 
made, furnish fundamental data that ultimately should prove of the greatest 
value in a scientific adjustment of diet, hygienic conditions, and the applica- 
tion of the muscular work of man to levers and other mechanical appliances. 
It is the purpose of this book to report a series of experiments conducted 
throughout the academic year of 1911-12 in the Nutrition Laboratory of the 
Carnegie Institution of Washington, located in Boston, with a professional 
athlete as subject. In these experiments the mechanical output was most 
exactly measured, and the chemical transformations inside the body were 
F. W. Taylor, The principles of scientific management, New York, 1911. 
