Exercise And Nutrition

4. Exercise And Nutrition

Some of the first accounts of athletics and nutrition go back to the early Olympic Games in Greece.  It was indicated (Harris, H.S., 1966) that there was a considerable insistence by Greek doctors on the importance of the diet that led to a keen interest in the diet of their athletes. Very little meat was originally consumed in Greece. The diet consisted of whole grains such as barley or wheat, eaten in cereal or bread form, and a variety of vegetables, such as onions, carrots, cucumbers, marrows, beans and various green leafy vegetables. Fruit was abundant, especially grapes and figs, apples, pears and nuts. The pomegranate was a prize. Although the Greeks did consume large amounts of goat milk products, adequate nutritional requirements were contained within the former food groups.

During the 1900’s there developed the popular belief that any form of sustained muscular exercise required an abundance of meat foods. It was postulated that during exercise the substance of the muscle was consumed, and therefore hard work would remove a considerable portion of the muscle material that could only be replaced by eating animal protein. However, a study was done in Zurich (Eggleton, 1948). Two scientists climbed one of the Bernese Oberland peaks, one living on a nitrogenous-free diet (free of meats), while the other ate a diet containing nitrogenous foods. They found that when they were resting quietly, the amount of nitrogen excreted was not increased by their physical effort, either during or following the climb. This served as the basis for the modern outlook on the relationship of muscular performance to nutrients, which is that the muscle oxidizes the sugar and fat for the production of its energy, and does not use up its own substance. Thus, it is only when the muscles are chronically inactivated or during starvation that the muscle tissue is actually used up.

Energy requirements are obviously dependent upon the amount and quality of the expended energy during various tasks. This is also modified by other factors. For instance, energy requirements vary widely with age. A newborn baby requires less total energy than either a full-grown man or woman.

Individuals vary to a certain extent in their caloric requirement, and in certain diseased states this variance is even greater. In colder climates, there is a greater loss of heat to the surrounding air, and thus more caloric intake is required to balance this offset. In a warmer climate, less heat is radiated by the body and therefore less calories are needed.

As previously stated, there is a difference between the caloric requirements for carrying out various types of physical exertion. Some items of interest from the original data published by Mary Schwartz Rose in the United States are noted below. In a healthy human being, sleeping generally requires 65 cal./hr.; standing relaxed requires 105 cal./hr.; light exercise, 170 cal./hr.; walking slowly, 200 cal./hr.; walking moderately fast, 300 cal./hr.; severe exercise, 450 cal./hr.; running slowly, 570 cal./hr.; an very severe exercise, 600-650 cal./hr.

Studies done just following W. W. II (Eggleton, 1948) indicated that a robust man doing heavy industrial work can metabolize 4000 calories of food during a working day. This raised the question of whether one variety of food is better than another in making up the calories consumed. Eggleton says that a good deal of evidence from the work on muscles and muscle extracts indicates that carbohydrates are the main fuel for exercise although some studies show that a proportion of the muscle fibers do utilize some fat for energy.

It is estimated that pure carbohydrate provides 1800 cal./lb. and so does pure protein; but pure fat provides 4200 cal./lb. The belief of these heavy laborers is that every time meat is consumed, a certain amount of fat is also consumed, and thus the total amount of food required to provide the same amount of calories is less when eating meats, than when eating just carbohydrates and proteins.

It is clear to see that our society is obsessed with caloric intake, with total disregard to the quality and composition of the foods which are consumed. There is much controversy about the composition of diet for athletes. Much of the controversy concerns the amounts of protein, fat and carbohydrates consumed and their relationship to exercise and athletic performance. When discussing the quality of diet with regard to these three nutrient groups, we must examine two salient questions: (1) Whether an excess of one of these three nutrients is more important than any of the others, when pertaining to exercise, and (2) Whether the consumption of one or the other of them on the day of exercise or the athletic event is likely to be of much significance.

As far as the latter question is concerned, the only substance which is likely to have a significant effect when taken before an event is sugar. By sugar we mean the simple sugar from fruits are most readily used, and then the more complex sugars which are broken down from starches (carbohydrates).

A study was done on the relationship of breakfast to athletic performance (Holdi & Synn, 1946) concerning the carbohydrate intake of swimmers with relation to a 100-yard swim. The results showed that the compositon of the meal, as far as carbohydrates were concerned, did not effect either the blood sugar level at the end of the swim or the performance. They concluded that the energy reserves of the body were more important than the composition of the pre-swim meal. The implications are that a long-term maintenance of a quality diet has a much greater effect on performance than does the administration of a quality meal just prior to exercise.

Another study (Karpovich, 1941) showed that the amount of carbohydrate metabolized in exercise is dependent upon the amount of carbohydrate in the diet, and the lower the carbohydrate in the diet, the higher the amount of fat metabolized. Karpovich also claims that when energy is derived from fats, the work performed is actually 10% less economical than when the energy is derived from carbohydrates. There is also little doubt that protein or fat, since they need such a long digestion period, produce little benefit when administered just before an athletic event.

In regard to the former salient question of whether an excess of the three nutrient groups (carbohydrates, fats, proteins) is more important than any of the others when dealing with activity, we find that all three substances are equally important and are readily available in appropriate amounts in the Hygienic diet.

Though recent trends in nutritional advice tend to overemphasize protein, all protein in our bodies does not come from outside protein sources. There is a constant interchange of carbohydrates, fats and proteins within our bodies. Food is used not only for the formation of the body, but also for the energy expended in daily exercise and activity. Though carbohydrates and proteins are somewhat interchangeable, carbohydrates are more readily required in volume during physical, metabolic exercise than proteins.

For the utmost efficiency in exercising and for physical exertion, we need a good deal of both simple and complex carbohydrates in our daily diet. Through the gradual decomposition of monosaccharides (simple sugars) and polysaccharides (complex sugars or carbohydrates), our metabolism and activity level is sustained. Therefore, it seems that the ideal diet for an active person or an athlete is based on fresh fruits, vegetables (including leafy green vegetables and roots to maintain the necessary amount of protein and calcium), nuts and seeds.

As mentioned earlier, we find that in many societies there is too much emphasis on caloric intake, with little regard to quality and composition of diet. We must consider that some foods convert into calories at a higher rate than others. For instance, simple sugars contained in fruits convert to calories more readily and thus caloric discharge ceases much sooner, than do more complex sugars contained in many vegetables and legumes, which are more slowly converted and burned into calories. Meat and dairy products are even more slowly broken down and converted, and cause a lot of wear and tear on the digestive organs. In this respect, a diet centered around fresh fruits, vegetables and a small amount of nuts and seeds is far superior to a diet centered around meat and dairy products.