104 
MUSCULAR WORK 
A most interesting series of experiments was carried out by Laulanie a 
on himself in which a wheel with a brake upon it was used. In one series 
the brake was adjusted so as to have a resistance of 4 kilograms, the experi- 
ments lasting 5, 10, and 15 minutes respectively. The results are collected 
in table 102. These experiments showed a constancy in the efficiency with a 
constant amount of work per unit of time. 
Still more important, however, was the series of experiments made by 
Laulanie \ on the same apparatus in which the rapidity of work was volun- 
tarily altered. The values of the resistance ranged from 1 to 15 kilograms, 
and the speed altered from 1.49 to 0.13 meters per second. The results are 
presented in table 103. 
Table 103. — Results of work experiments made by Laulanie with varying speed and resistance. 
Resist- 
Speed per 
Work pro- 
duced in 5 
minutes. 
Oxygen 
increase 
Oxygen 
consumed 
Net 
ance. 
second. 
due to 
per kilo- 
efficiency. 
work. 
grammeter. 
kilos. 
meters. 
kgms. 
liters. 
c.c. 
p. ct. 
1 
1.49 
448 
1,596 
3.5 
14.1 
2 
1.07 
642 
1,568 
2.44 
20.4 
3 
0.80 
726 
1,581 
2.17 
22.9 
4 
0.61 
778 
1,683 
2.14 
23.3 
5 
0.54 
812 
1,797 
2.23 
22.3 
6 
0.44 
853 
1,928 
2.25 
22.1 
8 
0.37 
896 
2,188 
2.43 
20.4 
10 
0.29 
905 
2,590 
2.53 
19.7 
12 
0.24 
906 
2,829 
3.12 
17.0 
15 
0.13 
570 
3,030 
5.31 
9.4 
This interesting table brings out the fact that the highest efficiency was 
obtained with a resistance of 4 kilograms, and with a rapidity of 0.61 meter 
per second, thus showing that there appears to be an optimum condition of 
mechanical work under these circumstances. Laulanie indicates two " opti- 
mum conditions," the "optimum mecanique" corresponding to resistances 
between 8 and 12 kilograms, and the "optimum economique" to a resistance 
of 4 kilograms. 
A series of computations of the mechanical efficiency of isolated muscles 
when stimulated should be cited here. Fick c found on isolated muscle under 
the most favorable conditions an efficiency of 25 per cent. Danilewsky, d 
employing similar methods, found an efficiency of 50 per cent, but Fick 
observed that these figures were improbable. 
Gautier e concludes that a man produces 250,700 kilogrammeters of 
gross work per day, which would be equivalent to 588 calories, and consumes 
a working diet, i. e., a diet in excess of the resting diet, of 1779 calories. 
He assumes that the efficiency is therefore one-third, but that of these 250,700 
kilogrammeters, 100,000 kilogrammeters and above are lost in the different 
movements of the body and the friction of the machine, so that the useful 
work corresponds to but 150,000 kilogrammeters, the equivalent energy of 
which would be 352 calories. The net efficiency, therefore, of the human 
motor would be approximately one-fifth. 
The two forms of muscular work most commonly employed by Zuntz 
a Laulani6, Elements de physiologie, 2d ed., Paris, 1905, p. 801. 
b Laulanie, loc. cit., p. 802. 
c Fick, PHuger's Archiv, 1878, 16, p. 58. 
d Danilewsky, in Fick's Myothermische Untersuchungen, Wiesbaden, 1889, pp. 173-194. 
e Gautier, Cours de chimie, Paris, 1892, 3, p. 800. 
