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.