It has been reported by Boothby that the onset of muscular fatigue can be delayed by the addition of a considerable amount of glycine to the diet of the normal individual. He has further shown that in cases of myasthenia gravis and similar diseases the feeding of glycine tends to restore the wasted muscle tissue, thus indicating an effect upon the physiological state of these tissues. Wilder believed his ability to play tennis increased after 2 weeks on a glycine diet. The possible explanation of these reactions is to be found in the ereatinogenie action of glycine and the storage of at least part of this product in the muscles. This is quite in accord with the current concept of the chemistry of muscular contraction wherein creatine in its combination with phosphoric acid plays an important role. The concept of storage is confirmed by the work of Rose, Ellis, and Helming, who found a male subject on a creatine diet could store this substance. This was not evident in the case of a female subject. Unfortunately, Boothby found that normal subjects were unable to take large amounts of glycine without some discomfort. It seemed of interest, therefore, to determine if a food rich in glycine would also increase the amount of work a trained subject was capable of doing before fatigue set in. Among the dietary possibilities, perhaps the most outstanding is gelatine, which contains about 25% glycine, is easily digested, and is readily available as a food substance. To the authors′ knowledge, none of the above papers, concerned with muscular fatigue and glycine, reported quantitative studies on the work output of their subjects. It was felt, therefore, that it was important that the amount of work done be measured as accurately as possible, both during a training period and during a period when gelatine was added to the normal diet.