20 MUSCULAR WORK 
was 845.3 calories and when protein was ingested, 855.6 calories. Since the 
heat equivalent of the work performed was 234 calories, the data give oppor- 
tunity for computing the mechanical efficiency of the body. 
The first report of researches carried out by Atwater and his associates ° 
with the respiration chamber at Wesleyan University, Middletown, Connec- 
ticut, included three experiments on muscular work in which a block of iron 
weighing 5.7 kilograms was raised and lowered by means of a rope passing 
over a pulley attached to the top of the respiration chamber. The move- 
ments of raising and lowering the weights brought into play not only the mus- 
cles of the arms but also the legs and other parts of the body, the idea being 
to induce severe muscular activity with no attempt to isolate any group of 
muscles. With this apparatus the subject did severe work for 8 hours on 
each experimental day. Throughout the working period he perspired very 
freely, and at the end he was thoroughly tired. The experiments were made on 
three successive days, during which time the subject remained in the respira- 
tion chamber the entire 24 hours. 
Later, by means of a stationary bicycle, the rear wheel of which was 
connected by a belt with a small dynamo, Atwater and Benedict made an 
experiment on muscular work with a subject inside the respiration chamber. 
At that time the chamber had been sufficiently tested as a calorimeter to be 
used for measuring exactly the heat produced by the body. 6 As in the earlier 
experiments, the muscular work period lasted 8 hours, the number of revolu- 
tions of the wheel being counted by means of a cyclometer attached to the 
bicycle. The heat equivalent of the external muscular work was estimated 
to be not far from 250 calories per day. 
This same bicycle ergometer, with its rear wheel belted to a small dynamo, 
was used by Atwater and Benedict in a work experiment which was published 
in 1902." The results of four additional experiments were also given in which 
a modified form of the ergometer was used. d As modified, the rear wheel of 
the bicycle was applied directly to a pulley fastened to the shaft of the dynamo, 
which was mounted on a rocking base, the necessary tension being secured by 
means of a spiral spring which kept the pulley of the dynamo pressed against 
the tire of the bicycle wheel. The detailed description of the apparatus and 
the method of calibration were not, however, given until a later publication 
in which additional work experiments were published.* This form of ergom- 
eter was calibrated before and after each experiment by running the dynamo 
as a motor and likewise by connecting another motor with the armature 
shaft and measuring the energy required to rotate the wheel of the apparatus. 
Employing a new form of bicycle ergometer, Benedict and Milner' 
report a large number of muscular-work experiments, covering several days. 
These were all carried out inside the respiration calorimeter at Wesleyan 
University, Middletown, Connecticut, the subject remaining in the chamber 
the entire 24 hours, the working periods usually being 8 hours in length. 
Certain of the experiments were designed to study the relative efficiency of fats 
« Atwater, Woods, and Benedict, U. S. Dept. Agr., Office Expt. Stas. Bui. 44, 1897, p. 51. 
& Atwater and Rosa, U. S. Dept. Agr., Office Expt. Stas. Bui. 63, 1899. In this description of the respira- 
tion calorimeter, Atwater and Rosa cite one of the experiments on muscular work (p. 76). See also 
Atwater and Benedict, U. S. Dept. Agr., Office Expt. Stas. Bui. 69, 1899, p. 47. 
c Atwater and Benedict, U. S. Dept. Agr., Office Expt. Stas. Bui. 109, 1902, p. 21. 
<l Atwater and Benedict, loe. cit., pp. 94-120. 
e Atwater and Benedict, U. S. Dept. Agr., Office Expt. Stas. Bui. 136, 1903, p. 30. 
/ Benedict and Milner, U. S. Dept. Agr., Office Expt. Stas. Bui. 175, 1907. 
