Eating For Strength
( Originally Published 1921 )
The earliest food chemists believed that protein foods, and especially lean meats were the best foods for giving one strength and energy; such a conclusion was only natural with their limited knowledge. Muscles were composed of protein, hence it seemed to follow that to gain muscular strength, one should eat similar substance, i.e., the muscles of animals.
The error in this reasoning was in assuming that the muscle in being exercised, or creating energy, consumes itself and, therefore, would need food substance of similar nature to replace the waste. This view we now know to be wrong, and that the muscle acts merely as an engine in which is oxidized or burned food fuel in the form of blood sugar. This blood sugar may be de-rived from protein, but that is not the best source from which to get it.
The protein theory of muscular strength was first shown to be an error by two European scientists who climbed Mont Blanc on a diet containing no protein. They showed that the loss of body weight during this arduous task was not sufficient to explain the origin of the energy acquired from the destruction of their own muscular tissue. As they ate no protein food they concluded that the source of muscular energy must come from the fat and carbohydrate foods which they consumed.
This belief that protein foods were the source of muscular energy died very hard in the scientific world. It is by no means dead yet in the mind of the man in the street, who believes that be must eat meat to keep up his strength. There is perhaps just a slight bit of truth in this still popular belief in the strength-giving qualities of meat. That effect is probably due to a slight immediate stimulating effect.
In my own experience as a wrestler, many years ago, I tried out various kinds of diet and observed their effects upon myself very carefully. I found that meat would increase my actual strength, but would lessen my endurance. I could lift a heavier weight under the influence of the diet in which meat was liberally supplied, but I could not lift a lighter weight so many times. I also discovered through those early experiments that eggs did not have this unfavorable effect on my endurance, though they seemed nearly, if not quite equal to meat as a means of supplying immediate strength. Both strength and endurance were essential to my work as a wrestler, and in my efforts to attain my greatest possible strength without loss of endurance, I adopted, after many long experiments, a diet containing a limited quantity of meat. I ate eggs frequently, but did not use meats oftener than once in two to four days; the bulk of my diet consisted of eggs, whole wheat bread, vegetables and fruit. Upon this diet I maintained such a fitness that no competitor ever gained a single fall from me in my favorite style of wrestling, though many of my opponents weighed from fifteen to fifty pounds more than I.
The evidence that a heavy meat diet is beneficial in increasing immediate strength is not as overwhelming or convincing as the evidence against meat in matters of endurance. For illustration: in a long distance race of 125 miles, which was run some years ago between Dresden and Berlin, there were thirty-two entries, twelve of whom were meat eaters and twenty vegetarians; the race was won by a vegetarian who was eight hours in advance of his best meat-eating competitor. Only three of the meat-eaters out of twelve finished the race within the prescribed time of forty-five hours, but ten of the vegetarians finished. The winner of the race had been a vegetarian for nine years and ate but two meals a day; his diet consisted chiefly of -whole wheat bread and uncooked fruits and nuts; he had discarded legumes beans, peas, etc.) from the diet, maintaining that they required too much vital force for digestion—a conclusion well borne out by present, scientific knowledge.
More recent scientific investigation has thrown much light upon this question of the diets best adapted for the production of the greatest strength and efficiency. This investigation of Horace Fletcher and his associates, to which reference has been made, indicated very clearly that a low protein diet resulted in superior physical efficiency. Mr. Fletcher himself broke several records at the Yale Gymnasium that had been made by the best of the college athletes. This achievement astonished the world because Mr. Fletcher, at the time was over fifty years of age and had not trained particularly for these tests, as had his youthful and over-nourished competitors. Fletcher's diet contained very little meat, the small quantity of protein being derived from milk and eggs. The systematic and carefully supervised experiments which were conducted at Yale following these demonstrations all gave convincing evidence that a minimum diet with very little protein, and "Fletcherized," that is, eaten slowly and exceedingly well masticated, would materially increase the endurance and efficiency.
When these experiments were made Mr. Fletcher gave the chief credit to mastication, while the scientists of Yale gave the chief credit to the low protein-both of these factors undoubtedly contributed toward the results. But in the light of very recent experiments we should also give credit to the reduction of the total quantity of food.
The limit of a man's physical endurance (which means his practical strength in all muscular operations, enduring for more than a few seconds) is due to the following causes: the limit of the breathing capacity; the limit of the capacity of the heart to carry freshrblood to the muscles; the accumulation of fatigue poisons.
As to the matter of breathing, there is no way to improve one's power in this respect, except by developing chest expansion and lung capacity. In the matter of circulation, as influenced by the rate of the heart-beat, some interesting facts were discovered during this test at the Y. M. C. A. College on the restricted diet. The pulse rate of the men on the restricted diet decreased; this would indicate that a less rapid flow of blood was necessary to furnish the required fuel and remove fatigue poisons from the muscles. Now, when these men were put through a tread-mill test, it was found that though their pulse rate was increased by the exercise it did not go nearly so high as the pulse rate of full-fed men; it would seem from this that the men on this minimum diet would have latent powers of endurance, because of this capacity to keep up a given amount of energy production with a lower pulse rate. The seeming truth of this reasoning is borne out by the practical observations of the increased en-durance upon an abstemious diet.
Fatigue is caused by the accumulation in the muscle cells of the waste products of their activities. These are constantly being removed by the blood stream, but the continued activity results in a certain accumulation in excess of the capacity of the blood to remove the waste. Some of these waste products are similar to those found in meat and the proportion of such products in meat would depend somewhat upon the degree of fatigue of the animal at the time of its death. It is thus argued against a meat diet that it adds to the fatigue poisons of our own activities, and others derived from the animals of which we eat.
The use of excessive protein, either of animal or vegetable origin seems to have a somewhat similar effect, for the protein which is not used by the body must be broken down into similar waste products before it can be eliminated from the body. The general sense of physical fitness derived from the use of a light diet and prefer-ably a light protein and meat-free diet is probably to be explained by this greater freedom from fatigue poisons.
The weight of the body and the amount of fat has an obvious effect upon muscular strength and efficiency. Any one knows that a fat man is weak and clumsy and that an athlete should train down to hard muscle before he can hope to win against his competitors.
In the past, however, athletes have often at-tempted to take off their fat by exercise, while still living upon a diet, the tendency of which was to put fat back on them. The exercise is certainly essential, but the task of training is made much more difficult where exercise and diet are thus at war with each other.
Probably the most efficient condition of the body is one in which the fat is reduced almost to the vanishing point. Just where this point is, is not easy to determine, for the reason that there is much fat deposited throughout the body, the presence of which does not show upon the surface of the body. In the experiments on restricted diets quoted in our chapter on "How Much to Eat," the young men, though athletic to start with, all lost ten per cent of their weight, and yet were able to keep up their strength. In fact, the comparison of the strength of these before and after losing this ten per cent of weight, was so close that, for the group as a whole, the averages showed that they had gained a little strength in one hand and lost it in the other. In the chinning tests several of the men on the restricted diet broke their previous records made on a full diet; eight out of twelve of these men held their arms extended for one hour.
I do not believe that these men could have shown such muscular efficiency if their loss in weight had been chiefly in muscular tissue, for such a loss from a 150-pound man would mean fifteen pounds, about one-fifth of his total muscular substance. The weights and photographs of these men showed them to be, at the beginning of the experiment, in about the condition of the average athletic individual who is eating rather heavily and training moderately. Such men evidently carry some surplus fat which they can afford to lose without any loss of strength.
The actual fuel burned in the muscle is physiological glucose or blood-sugar; it, therefore, follows that such sugar is the most easily available for the production of muscular energy. When the free supply of this blood sugar is consumed, the fat, either direct from the food or from the body, is next drawn upon, being. converted into sugar before it can be utilized in the muscles. After all fat is exhausted, as in the case of a starving man, then and only then do the muscles consume themselves or burn protein. When this point is reached, strength deteriorates rapidly and weakness and ultimately death occur. As long as there is a supply of sugar in the blood, or stored in a slightly altered form of glycogen in the liver, body fat will not be drawn upon; on the other hand as long as there is fat in the body the muscles or other active tissues will not be consumed.
From these statements we can draw the following conclusions: First, the best form of nutritive energy is that of blood-sugar; and as long as the supply of this is not exhausted nothing else will be consumed. (The loss of weight that occurs in ordinary athletic contests is chiefly due to the loss of weight of water.) Second: so long as man has any appreciable amount of fat in his body neither exercise nor the reduction of the diet can cause the destruction of his vital tissues or cells by muscular work.
As a practical application of these principles, in recommending a diet for muscular strength and endurance, we must place first in the list the foods that will produce blood-sugar. These foods in order of their ease of digestion and quickness of assimilation are as follows:—First: The natural food sugars, such as dates, raisins, grapes and honey. Second: Artificial sugars, granulated sugar and syrups. Third: Starches. Fourth: Fats.. Fifth: Protein. This rating of foods in order of their readiness for blood sugar production does not, of course, mean that the athlete should disturb the fundamental basis of a complete diet. The salts, vitamines and high efficiency proteins are required for the athlete as for any one else, but for the additional food that his extra exertions require, or for the immediate food to be used just prior to or while undergoing such exertion, the list as given shows the order of preference. The use of chocolate for soldiers on the march is well founded, as the sweetened chocolate so used is chiefly sugar with a smaller proportion of fat. Except for the matter of flavor plain sugar would do as well. But I believe the very best foods that can be found for this especial purpose are dried sweet fruits.
Part of the argument in favor of the use of such special foods during, or immediately preceding strenuous exertion rests on the fact that these foods require the least consumption of energy for their digestion and are least likely to make trouble with indigestion when the blood is drawn away from the alimentary tract, be-cause of the vigorous use of the muscles. Do not overlook the fact that the digestion of food consumes considerable energy particularly is this true of protein food. This energy spent on digestion adds nothing to the energy available for muscular exertion, but only puts an additional burden on the heart and lungs. In exerting the muscles for a few seconds the limit of strength is one of actual muscular power, but in endurance the limit is the ability of the heart to circulate the blood and the lungs to purify it. Here perhaps we see the reason why the meat diet does not effect strength but does effect endurance.
Where food must be taken during severe physical labor the foods requiring the least energy in digestion are obviously indicated. But it does not follow that one should be eating all the time during strenuous labor. Such use of sugar foods is necessary only during long marches, long cycling, swimming and walking contests, where the activity must be kept up constantly for hours or perhaps days. For ordinary athletic events it is much better to enter the contest with an empty stomach; the last meal should be taken several hours before such competition, and nothing can be superior for such a meal than sweet fruits with perhaps a glass or two of milk.
The eating of ordinary meals containing starches, fats and protein difficult to digest during periods of specially strenuous labor is a mistake—complete fasting would be better. This fact is well illustrated by the experience of as engineer who was working a twelve-hour shift alternating with a man who had the habit of not showing up, the result being that the reliable man sometimes had to work thirty-six hours at a stretch. The company very kindly provided a full meal, sent from a restaurant, every six hours. The result of a couple of such experiences was a serious case of illness. The next time it happened the engineer refused the food and went through the thirty-six hour shift on a fast; he then went home and had his sleep out, and came through the experience as fit as a fiddle.
Just as it is inadvisable to eat heavily imme=diately before or during an athletic contest, so one should not eat heavily immediately after.
It is highly important for the man who indulges in heavy exercise or labor for limited periods and has long periods of rest or light labor in between, to adapt his diet to the changed condition. Otherwise the habits of eating necessarily adopted during the periods of strenuous labor will be continued, the result is that he will be over-fed, even if he does not actually get fat. Such over-feeding will result in a stuffed and inefficient condition. He is particularly likely not to notice this, as the shrinkage of the muscles due to the discontinuance of exercise will permit of a considerable accumulation of fat before it becomes noticeable.
A great deal of time and physical efficiency is lost by boxers and other seasonal athletes in getting into and out of training. If their diet was more carefully adapted to their actual needs from time to time, getting back into shape would be much easier accomplished. But the worst mistake of this sort is that made by the average business man who spends his youth as a boy on a farm, or athlete in a college and ac-quires a hearty appetite, and then tries to keep up his eating capacity after he settles down into a swivel chair and indulges in nothing more strenuous than getting into and out of an automobile.
To attempt to prescribe the exact amount of food that should be eaten by the man doing heavy physical labor, and particularly by the athlete, is even more difficult and impracticable than to prescribe the amount of food for those of sedentary occupation. This difficulty will be readily seen by a glance at the following figures, which show the consumption of food energy under different conditions of physical activity.
Calories per hour
From such figures it is seen how very great are the differences of energy consumption with different forms of exercise. Hence to calculate how many calories per day an athlete would need, we would have to know the exact number of minutes engaged in sleeping, standing, sitting, walking and running, and so forth. Even this exact degree of exertion in all these conditions could not be known, to say nothing of the factors of the size of the man and his individual physical efficiency in converting food into energy—hence the absurdity of all such efforts to prescribe the exact amount of food that any man should eat.
We can also note from the above figures that the rate of consumption in such exercise as running would amount to 5,000 calories for a ten-hour day; a man who ran twenty-four hours—and it has been done—would consume 12,000 calories. All such figures are away above the capacity of a man to digest and assimilate food, hence these especially strenuous endurance tests are only possible from the temporary consumption of food stored in the body with the result that such special exertion causes a temporary loss in weight.
As a practical problem the athlete should gauge the amount of food eaten, not by calculation of calories, but by the weight of the body and the sense of physical fitness. The more muscular energy expended the greater will be the amount of food needed; but it does not follow that excessive eating will increase the muscular powers; quite the contrary is true. The ideal, in any case, is to eat just enough to sustain the general average expenditure of food energy. The muscles work more efficiently and endurance is greater when the body is not clogged with an excess of nutritive elements, and the vitality wasted first in digesting and then eliminating the use-less surplus. Therefore, it is much better to keep the average food consumption down near the minimum, even if it results in loss of body weight during the times of severe exertion, than it is to attempt at all times to eat enough for those periods of special energy expenditure, with the result of over-eating at other times and a general lowering of efficiency.