Rensselaer Union, Volume 8, Number 9, Rensselaer, Jasper County, 18 November 1875 — The Relation of Food to Work. [ARTICLE]

The Relation of Food to Work.

Dr. Du Chaumont in a recent lecture said that up to a quite late date there was .ah absence of any satisfactory theory as to the relation of food to work, and it was supposed that bodily force was due to a chemical change in' the muscles themselves, and that nitrogenous matter in food repaired the waste. But the researches of Joule, Playfair, Frankland and others on the conservation of energy have led to the conclusion that active force is produced chiefly-by the potential energy stored up in the carboniferous food and set free by oxidation. Hence it was seen that to credit the chemicalchanges in tlie muscles v ith the origination of force in the laxly was not more philosophical than to credit the force ex-" erted bv a steam-engine to the wearing away of its wheels and pistons. The lecturer then proceeded through a large number of elaborate calculations, based upon actual observation, for the purpose of showing tlie ordinary amount of productive work of which a man of average height is capable, and its equivalent in foot tons—a foot ton representing the amount of force required to raise one ton one foot high. It appears that the work done in walking three miles an hour is equal to about one-tenth the work done by direct ascent. Three hundred foot tons is a fair day’s work for a man of average height. This would be equivalent to walking fifteen miles in a little over five hours. A hard day’s work would be equivalent to walking twentyfour miles in eight hours. Dr. Parkes mentions an extreme case in which a man in a copper mill did as much as 723 foot tons in a day, his average work being 443 foot tons. The ordinary work of a military prisoner is 310 foot tons. The velocity at which work was done, and the consequent resistance, greatly affect the quantity of potential energy required for its accomplishment. For the production of any amount of what may be termed productive work a much larger amount of potential energy has to be expanded. Prof. Haughton, of Dublin, has calculated that, of the total potential nhergy produced in the body, 260 foot tons are required for tlie action of the heart. Then the animal heat absorbs from 2,000 to 2,500 foot tons, or more. According to Helmholtz, about five times as much energy is used in the internal work of the body as is expended in ordinary productive work. In the case of severe work the proportion of internal work to productive work is still greater. Supposing the work performed by a man to consist of walking, the most economical rate, both as regards the amount of food required to sustain it and the anpunt of potential energy expended on the body itself, is about three miles an hour. Both above and below that speed there is a decrease in the amount of active work as compared with the non-productive energy. A-man walking fifteen or sixteen miles a day, or doing an equivalent amount of work in another form, would require 23 ozs. of food, composed of albuminates 4.6 ozs., fat 3 ozs., starch 14.3 oz., and salts 1.1 ozs. This would yield a potential energy of 4,430 foot tons, and 300 foot tons for productive work. A mere subsistence diet for a man at fest would be 15 ozs., but with this amount a man would lose weight. About 7,000 foot tons a day of potential energy is about the greatest amount which is possible as a permanency. This would yield 600 foot tons of productive work. These calculations applyonly to men in health.— Scientific American.