Let us now turn our attention for a moment to the group of university athletes, remembering that these men had been in training for many months, and some of them for several years, prior to the commencement of the trial with a reduced proteid intake. In the words of the director of the gymnasium, “These eight men were in constant practice and in the pink of condition; they were in ‘training form’ when they began the changed diet.” Some of them had gained marked distinction for their athletic work; one during the early months of the test won the Collegiate and All-around Inter-collegiate Championship of America. Compare now the strength tests of these men as taken at the beginning and end of the five months’ experiment, during which they reduced their daily intake of proteid food more than fifty per cent:
TOTAL STRENGTH
| January. | June. | |
|---|---|---|
| G. W. Anderson | 4913 | 5722 |
| W. L. Anderson | 6016 | 9472 |
| Bellis | 5993 | 8165 |
| Callahan | 2154 | 3983 |
| Donahue | 4584 | 5917 |
| Jacobus | 4548 | 5667 |
| Schenker | 5728 | 7135 |
| Stapleton | 5351 | 6833 |
It is to be observed that the majority of these trained men showed at the first trial in January a total strength test approximately equal to that of the soldier detail at the close of their experiment. This by no means implies that the latter men owed their gain in strength wholly to the systematic training they had undergone, but it is certainly plausible to assume that in a measure this was the case. In any event, it is plain that the long-continued low proteid diet of the soldiers had not interfered with a progressive muscular development, and the attainment of a high degree of muscular strength.
The noticeable feature in the figures obtained with the athletes, however, is the striking difference between the January and June results. Every man, without exception, showed a decided gain in his muscular power as measured by the strength tests. This improvement, to be sure, was not so marked as with the soldiers; a fact to be expected, since with these men the element of training and the acquisition of proficiency in athletic work could have played no part in the observed gain. Further, most of the tests indicated that the gain was progressive, each month showing an improvement, in harmony with the growing effect of the diminished proteid intake. With these subjects, the only tangible change in their mode of life which could in any sense be considered as responsible for their gain in strength was the change in diet. Consequently, it seems perfectly justifiable to conclude that the observations presented afford reasonable proof of the beneficial effects of a lowered proteid intake upon the muscular strength of man.
The significance of such a conclusion is manifestly obvious. It confirms and gives added force to the observations that man can profitably maintain nitrogen equilibrium, and body-weight, upon a much smaller amount of proteid food than he is accustomed to consume. It harmonizes with the view that the normal requirements of the body for food, under which health, strength, and maximum efficiency are best maintained, are on a far lower level than the ordinary practices of mankind would lead one to believe. The widespread opinion that a rich proteid diet, with the correspondingly high rate of proteid metabolism, is a necessity for the preservation of bodily strength and vigor, is seen to be without foundation; for even the most conservative estimate of the real value of these strength tests must carry with it the conviction that lowering the consumption of proteid food does not at least result in any weakening of the body. This is a fact of vital importance, for it needs no argument to convince even the most optimistic that while it might be possible to maintain body-weight and nitrogen equilibrium on a small amount of proteid food, such a form of physiological economy would not only be of no advantage to the individual, but would be positively injurious if there was a gradual weakening of the muscles of the body with decrease of physical strength, vigor, and endurance.
Another fact to be emphasized in this connection was the conviction, gradually acquired by many of the subjects, that they suffered less from fatigue after vigorous muscular effort than formerly. This was especially conspicuous in the case of Donahue, whose work on the Varsity basket-ball team called for vigorous exercise. It is interesting to note that this athlete, of 63 kilos body-weight, for the last four months of the experiment showed an average daily katabolism of 7.45 grams of nitrogen, corresponding to a breaking down of 46.5 grams of proteid material daily. Yet, with this low rate of proteid exchange, he maintained his position on the team with satisfaction to all, and with the consciousness of improved physical condition and greater freedom from fatigue. Other subjects, as the laboratory workers of the professional group, observed that the customary late afternoon fatigue, coincident with the continued walking and standing about the laboratory, gradually became far less conspicuous than usual; so that there seemed to be a consensus of opinion that in some way the change in diet was conducive to greater freedom from muscular weariness.
It is well understood by physiologists that the ability of a muscle to do work is inhibited by any condition that tends to depress the general nutritive state of the body, or that interferes with the local nutrition of the muscle or muscles involved. On the other hand, there are certain well-recognized conditions that tend to augment the power of the muscle, notably an increased circulation of blood through the tissue, the taking of food, and especially the introduction of sugar. Further, experiments have shown that when a given set of muscles has been made to work excessively, other muscles of the body quite remote will share in the fatigue, thus implying that muscular weariness and the diminished power to do work are connected with what may be termed fatigue products, which are distributed by means of the circulation. In this way, muscles and nerve endings alike are exposed to the inhibitory influence of waste products of unknown composition, formed in the muscle, and as previously stated, we may conceive of an exaggerated exogenous katabolism, with excessive proteid intake, by which muscular fatigue and weariness may be augmented; hence, the beneficial effect in this direction of a more rational food consumption, by which proteid katabolism shall be reduced to a true physiological level.
With these marked effects on strength and fatigue, it is reasonable to assume that some corresponding action may be exerted on physical endurance. As is well known, strength and endurance, though related, are quite distinct and can be separately measured. Strength tests, however, as usually carried out in gymnasium work, do involve in considerable degree the question of endurance, since it is customary to use as one of the factors in estimating total strength the number of times the man can pull up, or push up, his body on the parallel bars. Strictly speaking, however, the strength of a muscle is measured by the maximum force it can exert in a single contraction, while its endurance is estimated from the number of times it can contract well within the limit of its strength.
It is well known that endurance, both physical and mental, is one of the most variable of the human faculties, and it is usually considered that exercise or training is the chief cause of the differences so frequently seen. The Maine guide will row a boat or paddle a canoe for the entire day without undue fatigue, while the novice, though he may have the necessary strength, lacks the endurance to continue the task longer than a few hours. As expressed by Professor Fisher, “Some persons are tired by climbing a flight of stairs, whereas the Swiss guides, throughout the summer season, day after day spend the entire time in climbing the Matterhorn and other peaks; some persons are ‘winded’ by running a block for a street car, whereas a Chinese coolie will run for hours on end; in mental work, some persons are unable to apply themselves more than an hour at a time, whereas others, like Humboldt, can work almost continuously through eighteen hours of the day.” Again, Fisher states that “among some 75 tests of different persons holding their arms horizontal, many were found whose arms actually dropped against their will inside of 10 minutes, whereas several were able to hold them up over 1 hour, and one man held them 3 hours and 20 minutes, or a round 200 minutes, and then dropped them voluntarily. Similarly with deep knee-bending, some persons were found physically unable to rise again from the stooping posture after accomplishing less than 500 bendings, whereas several succeeded in stooping 1000 times, and in one case, 2400.” Here, we have inherent differences in endurance not associated with training or exercise, and the question may well be asked, What is the cause of these radical variations in the ability to repeat a simple muscular exertion?