After 1 minute of walking, we find that, except for Can, the pulse-rates all increased as compared to the rate while standing outside the chamber. This would seem to indicate that Can's high pulse-rate of 81, although an average of three counts, was due to some unusual stimulus. The average pulse-rate for all of the subjects at the end of one minute of walking was 72. This was an increase of 20 beats or 38 per cent above the sitting rate, and 12 beats or 20 per cent above the standing rate inside the chamber. As was found with Squad B on January 28, the pulse-rate fell after the initial rise due to the stimulus of walking, and at the end of the second minute had dropped by an average of 4 beats, and 5 beats by the end of the fourth minute. The sixth minute showed a recovery of 2 beats. Subsequently, the rate varied slightly, reaching at the close of 12 minutes an average of 72 for 9 subjects, and 73 at the end of 24 minutes for 8 subjects. This was but 1 beat higher than for 9 subjects at the end of 1 minute, and it is in harmony with the results found with Squad B on January 6 and January 28. During the first 30 seconds of standing following walking, the average pulse-rate fell 12 beats from the rate at 24 minutes, and varied but 1 or 2 beats during the 120 seconds of standing, thus indicating the quick response of the heart to the requirements of the body. This rate was practically the same as that found during the preliminary standing period. In this respect, Squad A differed from Squad B on January 28 when the pulse did not return to the preliminary standing rate, at least in the time covered by the observation. The pulse-rates counted after 2 minutes of sitting, i. e., 4 minutes after walking ceased, show a further fall in rate of 13 beats. Taking for an average the rates at the fourth and fifth minutes, we find it to be 50 beats, or 4 per cent below the sitting pulse at the start of the experiment. By the end of 8 or 9 minutes of sitting, the pulse-rate had recovered and the average of 11 men was 52, or the same as the original sitting pulse.

Table 100. - Pulse-Rate Per Minute Preceding, During, And Following Walking In The Treadmill Chamber With Percentage Change From Rate Standing In Chamber Before Walking - Squad A, February 8, 1918

1Rate at 5 minutes.

2Based on rate standing outside chamber.

In table 101 are given the pulse-rates of 5 normal subjects referred to on page 436. The pulse-rates for the sitting position, preliminary to walking, are the average counts taken each minute for the 10 minutes during which the subject sat, except for E.L.F. and H.S., whose averages are from counts made for 6 and 7 minutes, respectively, of the 10 minutes of sitting. During the standing period, the average in each case is from counts taken each minute for 11 minutes. It is seen that the rate for H.M.S. remains very nearly uniform for the entire walking period at about 9 beats above the standing rate. While the data for H.W.F. are not so complete as for the others, they show a smaller initial change in the rate with greater variations during the period of walking. E.L.F. has a larger initial change than the others and this rate is maintained throughout the walking period on the whole rather uniformly. The rate of T.M.C. after the first minute shows a decided drop which is then maintained approximately 5 beats above the standing rate. The changes in the rate of H.S. are similar to those of T.M.C. for the first third of the period but show greater variations as the period progresses. The average increase in the pulse-rate from sitting to standing is 8 beats or 12 per cent of the sitting rate, and the increase due to walking 1 minute is 9 beats with a rate of 85 beats, or 12 per cent of the standing rate. During the succeeding 3 minutes, there was a fall to an average rate of 81 beats at the fourth minute and a subsequent increase to 85 beats by the sixth minute. The latter was the rate found at the end of the first minute and was maintained practically unchanged during the remainder of the walking period. The fall in the pulse-rate following the first minute of walking, and its subsequent recovery by the sixth minute is in character the same as with the two diet squads, though perhaps not so pronounced. There are records for but 3 of the 5 subjects at the end of 30 seconds of standing after the walking ceased. These three have an average rate of 76 beats which is a fall of 9 beats from the preceding walking average for 4 subjects, and the same as the group average for the preliminary standing period. This rate was not maintained and rose to 79 beats at the end of 1 minute, and to 86 beats by the end of 3 minutes. At the end of 9 minutes, the average rate for E.L.F., T.M.C, and H.S. was 82 beats, or 4 beats above the average preliminary standing rate for these same subjects. The sudden rise in rate for H.S. between the first and second minutes after walking ceased and an almost equally sudden fall at the eighth minute are to be noted, although no cause can be assigned for these changes. The increase in rate for H. W. F. at the end of the second minute may be accounted for by the fact that two members of the staff were discussing a point of the experiment within his hearing.

Table 101. - Pulse-Rate Per Minute Preceding, During, And Following Walking In The Treadmill Chamber With Percentage Change From Standing Rate; 5 Normal Men

1Rate at 7 minutes.

2Includes E. L. F. at 5 minutes.

From the records of the final sitting pulse it is seen that with neither H.M.S. nor T.M.C. did the rate return to the normal sitting pulse, although observations were continued with H.M.S. for 12 minutes. These two men were older than the other normal subjects, and the subjects in Squads A and B, with the exception of Pec. The pulse-rates of the other three subjects were below the preliminary sitting pulse at the end of 30 seconds and the average varied but slightly during the subsequent observations. The average sitting pulse for the group had dropped 15 beats from the standing rate by the end of 30 seconds of sitting or 1 beat below the preliminary sitting rate, and this rate varied but 2 or 3 beats during the succeeding 8 minutes. In this respect the 5 normals did not show such deviation from the preliminary sitting rate as did the other groups. It is to be recalled, however, that the pulse-rates of Squads A and B taken after walking were in all cases radial counts after the subject had left the chamber and was sitting in an adjoining room, while the normal subjects sat on a chair placed on the treadmill in the chamber and the pulse was counted by the deflections of the galvanometer string.