New dietetics for the man under exertion by Jean-Pierre de Mondenard

The mountain of articles, publications and statements on the subject of his diet leaves the athlete, whether he is merely an amateur or a top-level runner, completely confused. It is a fashionable subject which had let to an increase in the myths and false science which are prejudicial to objective information... In this article, which is necessarily limited, we are going to try to deal with this important problem by referring to the most recent scientific work, borne out by experience in the field. We do not presume to give a “miracle recipe”, but merely to indicate, in the light of objective information, what would appear to be the ideal. There are two points to be made first of all : 1. The physiology of “the man under exertion” is an expanding science. We should be fully aware that it deals with up-to-date knowledge, likely to change to keep in line with progress made in research in this field. 2. The athlete’s diet is an extremely vast subject; it depends on the type of exertion, its duration, its intensity, and the muscles (or rather the muscular fibres) used. We will restrict ourselves therefore to the long distance runner, i.e. distances over 10 km. In preparing this article, we looked at a large number of reports, articles and works by leading international specialists who have worked on the evolution and requirements in energy substrates during intense exertion over a long period i.e. exertion lasting longer than 60 minutes at 75 % of maximum capacity. These were by the Scandinavians Astrand, Hermansen, Saltin, etc., the Americans Costill, Gollnick, etc., and experts from the Eastern bloc countries, particularly the German Democratic Republic. We have noted that there is a definite convergence and it is this synthesis that we pass on to you. Before doing so, we would like to make a comment on the supposed differences of opinion which exist between certain researchers of international reputation. We will give two examples : Astrand remains a staunch supporter of the formula of the Scandinavian dissociated diet (in the second edition of the Handbook of Physiology of Muscular Exercise which has already been published in the United States in 1977, the French translation of which has just been published by Editions Masson) ; he describes at length the whole method and his opinion leaves no room for doubt. We will also give the example of Costill who has introduced, it is true, some variations into the types of diet to which we refer, but whose links with the Scandinavian laboratories are still very strong. He has just spent a year in Oslo, at Lars Hermansen’s Muscle Physiology Laboratory, where they carried out research together. It is all too frequently forgotten that when we speak of the athlete’s diet it is not a question of having a rigid programme, but of knowing if the main physiological foundations are correct in order to adapt them to each individual. Background As the American physiologist Gollnick recalled at the scientific conference on the marathon (New York, 23rd-28th October 1976), it is the Scandinavian researchers Christensen and Hansen who demonstrated in 1939 the effect of certain types of diet on performance, by highlighting the role of carbohydrates. But the work which was to provide the foundations of modern diets for athletes was carried out in the sixties thanks to the use of the muscular biopsy discovered by the Swede Bergstrom. It is to the team made up of Bergstrom, Hultman, Hermansen and Saltin that we owe the important research carried out on the effect of diet combined with intense exertion, enabling the achievement of an increased stock of muscular glycogen and thereby the possibility of maintaining intense exertion for longer or of improving performances... . Since then, work in this field has not ceased to develop, thanks to close co-operation between the Scandinavian and American physiology laboratories. Use by athletes All the researchers we have mentioned have always taken care to not base their findings solely on laboratory results, but to check the practice of their theories in the field. It is obvious that they were first used in Scandinavia. Astrand was to recall at the congress in Saint Etienne in 1977 that thanks in part to the use of a highcarbohydrate diet, the result of work by Christensen and Hansen, Scandinavians were the winners a good many times during the fifties and sixties of long distance events, particularly cross-country skiing. Ron Hill above all, at the end of his triumphant arrival in the marathon at the European championships in 1969, was to make the “Scandinavian Dissociated Diet” better known at a time when it was a complete novelty. He told a journalist that it was thanks to this formula that he had been able to leave Roelants behind in the last kilometres. Since then this type of diet with variations has spread far and wide outside Scandinavia, to the United States, into Britain and to a number of the Eastern bloc countries... In France these methods remained controversial, but it should be noted that the French cross-country skiing team has used them since the 1976 Olympic Games, as have a certain number of marathon runners. Two congresses have been held in Saint Etienne (in 1977 and 1979), bringing together the world’s great specialists in these matters, to try to take stock of the basic principles and make them better known. Even so, there is still much work to be done in spreading information. We have noted many errors in interpretation, or even worse whimsical uses which distort the results. The subject of the athlete’s diet is not a straightforward one; it is necessary already to have a good knowledge of the human engine, otherwise contradictions or mistakes are made which could have a direct effect on performance. Physiological foundations During exertion, whether it be training or a competition, we are like cars-we need fuel, and it depends on two aspects : a) Quality of the fuel - glycogen (particularly muscular glycogen) or “high-octane” fuel, used up first during intense exertion (over 70-75 % of our capacity). - Fats (stored, particularly in fatty tissue) or “low-octane” fuel used as a supplement during intense exertion, or on its own during our normal activities. b) Tank capacity - “High-octane” or glycogen : very small and almost exhausted after 90 minutes of at 70-75 % intensity (this is one of the reasons for flagging after 30-35 km in a marathon). - “Low-octane” or fats : extremely large, but with a lower return. This is the fuel which is used when the glycogen is exhausted, but it results in a loss of speed. Next: Important Comments Sporting Diet Primitive Peoples The founder's era in sport Vegetarianism Investigations History A glance at the practical side New dietetics for the man under exertion New dietetics for the man under exertion - Diet and Performance Different types of diet