Food Fads for Athletes
DR. JEAN MAYER, associate professor of nutrition in the Department of Nutri~ lion, Harvard School of Public Health, is also a lecturer on the history of public health at Harvard and a consultant in nutrition to the Children’s Medical Center, He is a Fellow of the American College of Sports Medicine.
THE campus of an American university in the year 1961 ought to be the last place where we should expect to find food fads. There is an increasing fund of sound information concerning proper nutrition; much of it has been developed in the universities themselves and is available there for the instruction and guidance of anyone involved in the feeding of students, staff, and faculty. Nevertheless, food fads flourish in the dining rooms of some of our universities.
From correspondence and conversation with a number of coaches, athletic directors, deans of colleges of physical education, and team physicians, I have come to a gloomy conviction. Food faddism is extremely widespread wherever groups of young Americans are being fed for power and prowess. The coach may, through the agency of various training talks and team instruction, put his boys on some whimsical diet which he has earnestly devised, or which has been confided to him by some garrulous warlock. Such a diet may entail prolonged avoidance of fluids, omission of entire classes of wholesome foods, or ingestion of large amounts of unnecessary and expensive things (royal jelly, a true bee in the nutritional bonnet, at one outstanding college). Or, probably far worse, the diet may be confidently slanted toward what turns out to be a ration excessively high in saturated fats, notorious collaborators in the increased incidence of atherosclerosis. As far as scientific nutritionists can determine, it cannot be proved that any of these diets do any good, and it can be established that many of them do harm. In common with much other quackery, they do have solid historical precedents.
For example, one of the old stand-bys of trainmg-table behavior has been the consumption of fabulous quantities of meat, supposedly destined to replace the protein losses erroneously believed to be incurred during severe muscular activity. This program has been traced back to the fifth century B.C. Until that period, the diet of Greek athletes had been mainly vegetarian. It had consisted of porridge, meal cakes, figs, some fresh cheese, and only occasionally meat, as a relish. The change took place shortly after the Persian wars, when a trainer, Dromeus of Stymphalus, who twice won the long race at Olympia, in 456 and 460, introduced the meat diet. This new diet, the appearance of which coincided with the rise of professionalism in Greek sports, was meant mostly for wrestlers; classification by weight was then unknown and the heavyweight had a decided advantage. Such extremes in athletic training were denounced by Hippocrates as “producing a dangerous and unstable condition of body,”
Many of the more bizarre nutritional notions of today’s coaches echo Greek, Roman, or even older tribal advice. A recent best seller attributes to honey a number of exceptional properties in athletic nutrition. While consuming honey is a pleasant, if sticky way to take carbohydrates, there is no evidence that honey is inherently superior to other carbohydrate foods.
A legitimate question right here might well be, “What is known about the effect of diet on athletic performance?”
Some study has been made on the effect upon prolonged physical work of the spacing of meals, the number of meals consumed, and the relative size of meals. Not all students of these matters have been in complete agreement about their findings, but enough directions have been charted to permit limits of sense and safety to be drawn. One experiment seemed to establish that frequent meals improved overall performance, that a pattern of five meals a day led to a total work output greater than was obtained with three meals a day. Reduction to two meals, by omitting breakfast, led, not unexpectedly, to inferior performance, particularly in the morning. Other experimenters, however, did not find a significant increase in the productivity of workers given snacks or meals of various compositions and sizes at midmorning and midafternoon breaks. One authority has concluded that when replacement of a few large meals by more frequent smaller ones leads to higher efficiency, it may do so through psychological effects. He declares, “With breakfast as a possible exception, the ingestion of food is not followed by any great increase in industrial productivity or improvement in athletic performance.”
There is ample support for the contention that omitting breakfast or cutting it down to a cup of black coffee causes a decrease in maximum work output, and an increase in reaction time and muscle tremor. Work following no breakfast or a negligible one has precipitated the onset of dizziness and nausea.
During the period of Ramadan, the Lent of Islam, Muslims eat only two meals a day — one early in the morning, the other at six in the evening. During the rest of the year, they customarily consume three meals a day. Timed races conducted in South Africa during the Ramadan and at another time of the year showed better performance during the three-meal period.
No detailed, controlled study conducted under actual athletic conditions is available. All in all, however, evidence does suggest that athletes should have at least three meals a day, or perhaps more frequent light meals, particularly if the sport concerned requires long hours of effort, such as skiing, distance running, or swimming. Exercises of shorter and less demanding expenditures of energy should not require any drastic modification of the pattern of meal distribution, except that, from the viewpoint of digestion, scheduling the last meal three hours prior to an athletic contest does make sense. It eliminates the drain on the circulatory system coincidental with active absorption. What is more, any nervousness felt by a performer just before a contest is less likely to interfere with digestive processes if this last meal is eaten well in advance. Exception: the speed with which a small sugar supplement is digested exempts it from such restrictions.
SO MUCH for the spacing of an athlete’s meals; now for some attention to their content. For it is in this area that the food faddist is often most opinionated, and it is here that the nutritionist has a considerable body of experience upon which to base his suggestions. For example, nutritionists know that carbohydrates are more swiftly turned into energy than fats are. It has been established that, while carbohydrates yield only half as many calories per gram as fat, burning carbohydrates yield more calories per liter of oxygen than docs burning fat. Therefore, on theoretical grounds, we might expect that in any sport where the oxygen supply to the tissues is a limiting factor, the use of carbohydrates might be advantageous.
Two main types of studies have been conducted to determine the possible advantage of carbohydrates or fats as physiological fuels: those in which athletes exercise after eating single meals of the items being tested, and those in which athletes are fed for several days a special diet high in a particular component (carbohydrate, fat, or protein). and low in the other two, to “saturate” the body with the type of food undergoing the test.
Studies made on athletes who exercised alter a single meal have, in the main, indicated that in exercise of short duration, readily available stores were sufficient, so that muscular efficiency was not affected by the size or type of preperformance meals. If an athlete is going to swim only a hundred yards, it cannot be authoritatively said that carbohydrates will be a better choice for his presprint meal than fats will. It is, nonetheless, true that some nutritionists would still vote for the carbohydrates to dominate the menu served before brief and demanding sports events.
When we come to the problem of diet for prolonged exercise, however, there appears to be better evidence in favor of having the carbohydrates dominate. One experiment measured the energy available for light exercise from a highcarbohydrate diet, a normal diet, and a high-fat diet. Following the fourth day of the test, there was a decline in endurance on the high-fat diet. Another experiment found that a subject could continue strenuous work three times as long on a high-carbohydrate diet as on a high-fat diet.
A particularly significant experiment was one in which athletes were maintained for several days prior to exercise on high-fat diets, high-carbohydrate diets, and mixed diets, successively. After each of these periods of dieting, the athletes participated in directed exercise. Endurance was impaired on the high-fat diet and was greatest on the high-carbohydrate diet. The scientist who conducted the experiment concluded that for sports involving patterns of rest and light expenditure of energy, trained athletes can fuel on meals emphasizing either fats or carbohydrates; but if the sports, either strenuous or light, are unrelieved by rest, carbohydrates are more useful to the athletes than fats are. Yet it is common practice at training tables to pack athletes with high-fat foods such as meat, eggs, and milk.
THERE are other erroneous notions at large. While it is true that enough of the right kind of protein is necessary for growth, the concept that muscular work, in athletics or heavy labor, uses up muscle protein, which then needs to be replaced, has been refuted again and again throughout the last hundred years. Yet coaches today call for unneeded protein for their charges as vigorously as did their Greek predecessors almost two and a half millenniums ago.
Some experiments have shown improved efficiency and well-being where customary protein intake, far from being increased, was cut almost in half, and this over a five-month period. It may be, of course, that the improvement was due to training, but it is difficult to support the claim that reduced protein intake worked any injury on physical performance. In a completely different experiment one group was fed a normal diet; another group had its protein intake restricted; while a third group was allowed three times as much protein. This went on for two months, while all three groups engaged in hard manual labor. Neither the lownor the high-protein intake appeared either to harm or benefit work efficiency.
Then there are the vitamins. That work performance is impaired and, in extreme cases, totally eliminated by vitamin deficiencies is well known. Less widely recognized by laymen is the difficulty of recognizing borderline deficiency cases. Accordingly, the uninstructed may attribute an improvement in work performance in a given individual to vitamin “supplementation” when the credit should go to the therapeutic effect of the vitamin on an unrecognized borderline deficiency. In an extensive series of tests carried out upon a group of pretrained army men receiving adequate diets, no beneficial effects of a surplus of five B-complex vitamins and ascorbic acid were noted on endurance, resistance to fatigue, recovery from exertion, or muscular strength and dexterity. Other tests conducted in other places found that athletes, like anybody else, needed to eat enough of the right things, including vitamins. But there was no evidence that athletic performance is improved by supplementing a nutritionally adequate diet with B vitamins or vitamin C. It goes without saying that should the bulk of additional calories required for exercise be provided by such purified foodstuffs as overmilled rice or refined sugar, additional B vitamins — enough to replace those lost in processing — would be helpful.
Some of the most radical claims made for the beneficial effect of vitamin preparations on athletic performance concern vitamin E. And here the nutritionists clearly disagree. Some experimenters found that dietary supplements of vitamin E and wheat germ oil made possible superior work performances at such strenuous activities as bicycle riding and treadmill running. Another worker alternated two groups of students with alpha tocopheryl acetate (a form of vitamin E) and placebos during two successive five-week periods, but discovered no significant reactions from the presence of the supplement in the diet. As of this writing, the virtues of vitamin E as a supplement seem highly dubious and those of wheat germ oil not proved.
A number of authors have come up with the hypothesis that a diet supplemented with glycine (a precursor of creatine) might increase the concentration of creatine and thereby the potential supply of phosphocreatine in muscles. (Phosphocreatine is a high-energy compound which is stored in the muscles and in the course of its splitting can furnish the energy necessary for the initiation and the early stages of muscular work.) Because of the high content — approximately 25 per cent — of glycine in gelatin, the latter has been advocated as a useful supplement. Its supporters believed gelatin might provide a quick source of strength. Experiments have shown that it does not. And it has been found valueless as a muscular pick-me-up in instances of fatigue.
Some popular writers have suggested that alkalinizing agents might alleviate fatigue or shorten the recovery period following exercise by neutralizing lactic acid. But, during a season of competitive cross-country running, students found no significant difference between the effects of glucose and those of various alkalinizing supplements on timed performance.
In sports such as boxing and wrestling, athletes often place themselves on crash diets to make lower weight classifications. These diets are often combined with deliberate dehydration. This is a woefully dangerous practice and should be strongly discouraged. The goal of these athletes is not to attain their most desirable weight from the viewpoint of health and fitness but rather to compete with an unfair advantage against an opponent who really does belong in a lower weight bracket. Today’s weight standards have been set up to provide competition on an equitable basis. Violating them by using such tricks as sudden selfinflicted starvation and temporary dehydration serves no more the ethics of sportsmanship than it does the health of the individual. He may be preparing himself not for triumph but for serious illness. The practice lias become so widespread and so conspicuously damaging that it has been condemned editorially by the American Medical Association.
CONTRARY to the contentions of the quacks, the optimum diet for an athlete in training is not different in any major respect from that which would be recommended to any normal individual. The diet should be adequate for maintenance, for growth if the individual is still growing, for increase in muscle mass if need be, and for the energy requirements corresponding to the athlete’s physical activity. Special attention might be given to the weight of the athlete in terms of desirability of possible gain or loss. When loss is indicated, crash diets should be avoided. Increased physical activity usually means that with moderate dietary controls, loss of fat can take place efficiently and relatively painlessly. If an increase in muscle mass takes place at the same time, the effect on weight of loss of fat may be counterbalanced by gain in body protein.
As I have said, in sports requiring endurance and prolonged muscular work, performance is better maintained on a high-carbohydrate diet than on a high-fat diet. In such cases, even the slight increase in efficiency on a high-carbohydrate diet (the maximum figure of 4 to 5 per cent has been indicated by many investigators) may well prove decisive. Carbohydrate reserves can be increased by two methods simultaneously: 1) Tapering off exercise forty-eight hours before competitive effort, and resting twenty-four hours before the event; 2) Shifting to a high-carbohydrate diet, particularly through the use of cereals, for the meal immediately preceding the event.
A major preoccupation of the team physician and coaches who have brought the athlete to the day of the competitive event in good nutritional shape is that nutrition should then not interfere with competitive performance, with its attendant physical and psychological stresses. The need to go to the toilet during a competitive event can be serious or even disabling. Proteins are a source of fixed acids which can make a toilet trip mandatory. Protein intake is therefore best reduced to the minimum at the meal preceding the event. Similarly, bulky foods — high-cellulose foods, like lettuce, and seed-containing vegetables, such as tomatoes — and highly spiced foods are best eliminated from the diet during the forty-eight hours preceding contests. Salt requirements can be met in a quantitative fashion by serving bouillon at least three hours previous to the event. If thirst ensues, it will occur at least an hour and a half before the event; drinking water then will permit elimination of excess fluid in time.
Nutritionists take a moderate view concerning alcoholic beverages, tea, and coffee. There is no evidence that small amounts of these in the training diet are harmful. On the other hand, there is good reason to avoid them just before an event: alcohol, even in small amounts, may have some effect on coordination. Coffee and tea, while stimulants, may have a depressing effect three or four hours later and thus impair performance if consumed at the preceding meal.
During a long and exhausting contest some sugar feeding does improve performance. Feeding glucose pills, pieces of sugar, or honey, however, tends to draw fluid for their digestion and absorption into the gastrointestinal tract and further dehydrate the organism. Strongly sweetened tea with lemon avoids this difficulty.
The practice of feeding athletes at training tables has to be justified essentially on the basis of convenience: athletes often start practice before colleges reopen; the sports schedule may be such as to necessitate different hours for mealtime. There may also be some psychological justification, in that these training tables may help to create a team spirit. But certainly, there is no nutritional justification for training tables now. The normal fare of schools and colleges should be wholesome and adequate for all students.
Some of the most successful coaches, such as Kiputh of the Yale swimming teams, have long felt that special diets and supplements take away the necessary emphasis on conditioning the body for fitness and the mind for competitiveness. Considering the important role that coaches can play in teaching sound health and nutrition habits to young men and women, it is to be hoped that more of them will abandon irrational dietary beliefs and help physicians and nutritionists in the battle against food faddism.