In this section we have endeavored to present as complete a picture as possible of the changes in pulse-rate level occasioned by the low diet with the accompanying change to a lower nutritional plane. We have presented data for the basal pulse-rate with the subjects in the lying position and with the subjects in the same position before riding the bicycle ergometer, with the subjects sitting and standing, and engaging in short periods of muscular exertion, also beginning to walk on the treadmill, during a prolonged period of walking, the transition following walking, and, finally, the recovery to the normal pulse-rate following a standard amount of work on the bicycle ergometer. The data have been presented analytically in each case and compared with the normal standard. This normal standard is rather fragmentary in the case of Squad A but fairly satisfactory for Squad B; in some cases there are other normals with which we could compare these low-diet pulse-rates.

It would appear as proved by the standard electrocardiograms that the lower pulse-rate characteristic of the low diet is not accompanied by any pathological changes but is a simple difference in the pulse-rate level between the condition of uncontrolled eating and the reduced diet. The actual values for the pulse-rate during rest are such as have never heretofore been observed with normal man, for a considerable number of men showed pulse-rates of 35 and below and one subject gave positive evidence of a rate of 29 on at least one day. Not only was the pulse-rate per minute very perceptibly reduced by the low diet, but the blood pressures have also been shown to be distinctly lower during the same period. (See p. 382.) These low blood pressures following diet restriction with both Squads A and B, taken in connection with the low pulse-rates, show clearly that the work of circulation of these men made a minimum demand on metabolic activity. We thus find here a most economically working heart, at least under normal conditions of rest.

During short periods of work, as in "chinning the bar" (p. 415), the percentage increase occasioned by this physical exercise was practically the same for normal men and for those on the low diet, that is, there was a simple change in pulse-level for the resting, working, and recuperation pulse with these short periods of work, i. e., periods less than one-half minute in length. With the pulse during work, judged according to the standards which we have, it seems clear that the men on reduced diet showed a greater percentage increase, as, for example, for the first minute of walking, over the level of the standing pulse, than the men on normal diet did. Following the bicycle riding it seems that the increase occasioned by the riding was slightly greater for normal than for reduced diet subjects; the only difference was that with the latter men there was a tendency to a quicker return to the normal base line. All in all, therefore, it seems that the pulse for the reduced diet condition demonstrates this difference, i. e. a lowering in the level without discoverable modification in the functional efficiency of the heart rate to meet the needs of the circulation of the organism under the varying conditions of rest and activity.