Sportscience History Makers

	by Frank I. Katch
INDEX	Santorio experiments breakthrough in energy metabolism

Wilbur Olin Atwater (1844-1907)

Atwater received his PhD from Yale in 1869 for studies on the chemical composition of corn. Studying in Berlin and Leipzig, he became familiar with the eminent German chemists and physiologists Voit, Rubner, and Zuntz. As Professor of Chemistry at Wesleyan College in Connecticut, USA, he studied the effects of fertilizers in farming and established the first agricultural experimental station in the United States at Wesleyan in 1875 (which in 1877 became part of the famous Sheffield Scientific School at Yale University). From 1879 to 1882 Atwater determined the chemical composition and nutritive values of fish and animal tissues. Returning to Germany in 1882-83, Atwater studied the metabolism of mammals in Voit's laboratory.

Cycle ergometer used by Atwater and his colleague Benedict in their studies on exercise metabolism.

The sensitive balance scales Atwater used in his metabolic studies.

Atwater's familiarity with German techniques for measuring respiration and metabolism helped him to conduct studies on food analysis, dietary evaluations, energy requirements for work, digestibility of foods, and economics of food production. He helped to persuade the United States Government to fund studies of human nutrition. Atwater directed various studies at agricultural experiment stations throughout the country that resulted in the 1896 publication of 2600 chemical analyses of American foodstuffs. An additional 4000 analyses were completed in 1899, including another 1000 analyses done under Atwater's supervision. The 1906 re-issue of the original report included the maximum, minimum, and average values for water, protein, fat, total carbohydrates, ash, and a food's "fuel value" calculated using Rubner's methods. Most commercial diet analysis programs currently incorporate Atwater's databases of food composition values.

Atwater compared US food evaluations with those from Europe. Although Voit and other agricultural chemists advocated a minimum protein intake of over 100 grams per day, Atwater felt this amount to be excessive. He recommended controlled dietary studies to determine how nutrient intake affected metabolism and muscular effort. After reviewing his dietary studies, Atwater worried that the population consumed too much food, particularly fats and sweets, and did not exercise enough:

It is a fair question whether the results of these things have induced among us in a large class of well-to-do people, with little muscular activity, a habit of excessive eating and may be responsible for great damage to health, to say nothing of the purse (Maynard,1962, citing Atwater.) .

Inside the Atwater-Benedict human calorimeter.

The metabolic studies Atwater began just before the turn of the century contributed most to the emerging science of human nutrition and exercise. Over a 12-year period he and E. B. Rosa (Professor of Physics at Wesleyan, and later chief physicist of the National Bureau of Standards) perfected the most accurate respiration calorimeter for studies of human metabolism. Accounting for almost 100 percent of the heat produced and substrates metabolized, this system allowed them to quantify the dynamics of energy metabolism, directly measure the balance between food (energy) intake and energy output, and evaluate the effects of diet and muscular activity on metabolism. The classic papers of Atwater and Rosa (1899), Atwater and Benedict (1905.), and Benedict and Carpenter (1910), with their meticulous technical detail and experimental procedures, should be studied by all who are interested in exercise nutrition.

Atwater's scientific lab.

Before Atwater died in 1907, he had completed more than 500 energy-balance experiments. Maynard (1962) believes that Atwater's most valuable contributions concerned human energy balance. They confirmed that the law of conservation of energy governed transformation of matter in both the human body and inanimate world. Atwater's comments penned in 1895 sound contemporary:

Food may be defined as material which, when taken into the body, serves to either form tissue or yield energy, or both. This definition includes all the ordinary food materials, since they both build tissue and yield energy. It includes sugar and starch, because they yield energy and form fatty tissue. It includes alcohol, because the latter is burned to yield energy, though it does not build tissue. It excludes creatin, creatininin, and other so-called nitrogeneous extractives of meat, and likewise thein or caffein of tea and coffee, because they neither build tissue nor yield energy, although they may, at times, be useful aids to nutrition (Atwater, 1905).

For other history makers in exercise nutrition, refer to McArdle, W.D., Katch, F.I., and Katch, V.L.. Sports and Exercise Nutrition. Williams and Wilkins. Baltimore, 1999. See preview (from mid-March).

References

Atwater, W. O. (1895). Methods and Results of Investigations on the Chemistry and Economy of Food. Bulletin 21, U.S. Department of Agriculture, Office of Experiment Stations, Government Printing Office, Washington, D.C.

Atwater, W. O., and Rosa, E. B. (1899). Description of a New Respiration Calorimeter and Experiments on the Conservation of Energy in the Human Body, Bulletin 63, U.S. Department of Agriculture, Office of Experiment Stations, Government Printing Office, Washington, D.C.

Atwater, W. O., and Benedict, F. G. (1905). A Respiration Calorimeter with Appliances for the Direct Determination of Oxygen, Carnegie Institute of Washington, Washington, D.C.

Benedict, F. G., and Carpenter, T. M. (1910). Respiration Calorimeters for Studying the Respiratory Exchange and Energy Transformations of Man, Bulletin 123, U.S. Department of Agriculture, Office of Experiment Stations, Government Printing Office, Washington, D.C.

Maynard, L. A. (1962). Wilbur O. Atwater-a biographical sketch. Journal of Nutrition, 78, 3.