From the standing transition curves it is found that the average pulse-cycle duration for walking immediately preceding standing is as follows: T.M.C., 0.68; E.L.F., 0.65; H.W.F., 0.67; H.M.S.,0.72; H.S., 0.65 second. At the tenth, twentieth, and thirtieth cycles after walking ceased, we find that the durations for the group have lengthened 0.03, 0.04, and 0.06 second, respectively. Using the preliminary standing values as a basis of comparison, we find that the post-walking values are, for the group, 0.04 second shorter at the tenth cycle than the pre-walking values, exactly the same at the twentieth cycle, and 0.01 second longer at the thirtieth cycle. If we compare these sets of figures with those found in a similar way for Squads A and B and given on pages 431 and 435, it appears that this lengthening in the pulsecycle duration immediately after walking was greater for the two diet squads than for the five normal men.

The most apparent difference between these five curves and those for Squads A and B, given in figures 95 to 100, inclusive, is that they are flatter and do not show such wide fluctuations. It should be remembered in this connection, however, that the pulse-rates of these normal subjects were faster than those of Squads A and B; consequently, in the 60 seconds of the walking record, there are more cycles to plot and the individual differences will not be so large. Bro (figure 98) and Tom (figure 100) had pulse-rates more nearly like those of the normals, and the curves for these men show more similarity to those of the normal subjects. Moreover, a change of the same increment with a pulse of a slow rate has a greater percentage value than with a pulse of faster rate. Before it can be definitely stated that one group shows greater fluctuations than another, these variations should be compared on some form of percentage basis. An attempt to do this is made in table 97, in which the average minimum and maximum pulse-cycle lengths in the walking and standing portions of the transition records have been noted, and the percentage increase of the maximum over the minimum duration is given. This takes into account the two extremes but does not allow for the possibility of more frequent variations occurring with one group than with another. The figures in the table show that in the walking transition the average difference between these two extremes is least with the five normals and greatest with Squad A on a 120-day restricted diet. In the standing transition following walking, Squad B has the smallest percentage difference, and the five normals have the largest difference.

Table 97. - Comparison Of The Minimum And Maximum Durations Of The Puke Cycles While Walking And Standing For A Group Of Normal Men, Squad B, And Squad A

It would appear, then, that during the walking transition Squads A and B had not only larger pulse-cycle variations than the normals had, but when calculated as in table 97, the percentage changes were also larger. For the transition from walking to standing, the actual differences in the extremes are practically alike for the three groups, but no striking relationship is apparent on the percentage basis.

A comparison of the changes between the average standing pulse-cycle duration preliminary to walking and that of the average duration of the first crest after walking began shows for the 5 normals a change of 0.07 second, for Squad B 0.29 second, and for Squad A 0.24 second, or a percentage change from the standing pulse-cycle duration of 10 per cent for the 5 normals and 25 and 23 per cent for Squads B and A, respectively.

A comparison between the changes in the duration of the pulse cycle for standing and the durations that would correspond to the pulse-rate found after 6 and 24 minutes of walking shows the normals had the least tendency to a shorter duration.

The curves of all three groups show that the pulse cycle lengthened after the first reaction to the stimulus of walking. This change to a lengthening cycle occurred between the fifth and tenth cycles, as a rule, both with the normals and with Squads A and B. The lengthening of the cycles continued to about the twentieth beat, when again a shortened duration appeared which usually was persistent, and the cycle did not again return to the duration shown at approximately the twentieth beat.

Recognizing the facts that the data here available are incomplete and that we are dealing with an organ extremely sensitive to the mental and physical conditions of the subject, which thus makes conclusions upon its normal behavior difficult, we may say that there appears to be no decrease in the promptness with which the heart responds to the stimulus of walking, and the other characteristics of the pulse aside from rate have not been fundamentally changed by the restricted diet. From the foregoing it is seen that (1) the average percentage variation for Squad A is greater than that for Squad B; (2) that of the three groups the 5 men with normal diet showed the smallest variation in the pulse-cycle duration in the changes from standing to walking and from walking to standing, and likewise the least variations in the maximum and minimum durations during the first 60 seconds of walking; (3) that these men showed less change than the men with low diet between the preliminary standing pulse-cycle duration and the duration which would correspond to the rates found after walking 6 and 24 minutes. These facts would seem to indicate a greater sensitivity of the heart to demands upon the circulatory system when the body was existing on a restricted diet.