A 100 per cent fatigue curve may be produced, then, only when
the number of foot contacts decreases in each successive inning.

Should the subject fail to put forth his best effort,—“go all-out”
—in any one inning that failure would be apparent by no score
decrease in the next period. In fact, a self-imposed easy session
usually is followed by one with an increase in foot contacts. Lack
of steady decrease in scores indicates an error in “application” by
the runner, and shows that there are inhibitions operating within
him guarding from overwork. In calculating these errors 10 per
cent is subtracted for each period in which no decrease in score
occurs. ‘Thus, a 90 per cent fatigue curve indicates that the runner
failed to do his best in one period.

After the pattern of the 100 per cent curve was established in
preliminary tests, it was found that repetitions of the test could be
used to measure improvements in Production and Application.
That is, when a subject later repeated the test, his production
record tended to increase. The improvement could be charged to
mastery of the skill, to more intense application, or to better
physical condition developed by the previous test. Of the three
possibilities it was found that the improvement in production
resulted almost entirely from better condition brought by the
training.

The next and last step was to measure how much these vigorous
work periods affect the various organic systems of the participants,
and whether or not any of them had been damaged. In this meas-
urement time did not allow complete examination of all vital
organs, but since the actions of the heart give accurate indications
of physical fitness the pulse rates were recorded. Physical fitness is
more than an ability to execute a skill; it involves an ability to
recover rapidly from the effects of fatigue. Pulse rates taken just
before a measured work period, and for several periods imme-
diately after the effort give a true picture of the speed of recupera-
tion. A series of individual fatigue curves combined with pulse
records, thus can be used to measure amount of effort; to note
improvement of production and application; and to show the
effects of exercise upon physical condition.

In these tests the heart rate was recorded before the subject
began spot running and immediately upon ceasing. Then addi-
tional pulse recordings were made after two, four and six minutes
of rest. The statistical data collected show clearly that regulated

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