8. Pulse Rate.

The alterations that were observed at rest
and standing in the training cardiacs were
also observed during exercise (Figure 3).
At each comparable oxygen requirement, the
pulse rate was 12 to 20 beats per minute lower
(P 0.05) in the training cardiacs; no differ-
ence was observed in the sedentary men. In
the initial tests, the mean pulse rates were
122 for the training cardiacs, 129 for the
sedentary cardiacs and 126 for the sedentary
controls during the 12th minute of walking.
Eight months later, these values were 103,
126 and 120, respectively.

SEDENTARY CARDIACS

TRAINING CARDIACS. SEDENTARY CONTROLS

Ficure 3. The pulse rate was 12 to 20 beats per minute
lower throughout the test following the physical
conditioning. Retesting did not influence the pulse-
rate response in either sedentary group. The adapta-
tions of the two sedentary groups were quite similar
throughout the tests, (All values represent the mean
determination for 12 subjects.)

D. Mean Test Performances.

Eight of twelve controls and six of twenty-
four patients completed the entire test ini-
tially (Table 3). Eleven of twelve training
cardiacs performed the 18-minute test 8
months later, whereas only three of the
twelve sedentary cariacs completed the sec-
ond test.

IV. Discussion.

Several investigators have established physical-
conditioning programs for cardiac patients. An
early report ? indicated that patients experienced
clinical and psychological improvement during

such a program. A more recent study * reported
improvements in certain motor-performance tests
in four cardiac patients during a conditioning
program, Despite widespread interest in physi-
cal rehabilitation for cardiac patients, there are
still no standardized guidlines with which to
select patients, to evaluate the progress of each
subject, or to establish the minimal level of ac-
tivity necessary for achieving a conditioning
effect.

These data indicate that the nonsymptomatic
patient who has recovered from a myocardial
infarction can develop a cardiovascular response
consistent with that observed to occur in pre-
sumably healthy men following physical condi-
tioning. * These altered responses were ob-
served during rest, standing and comparable
levels of energy expenditure. The most objective
measurement was the pulse rate, since it could
be confirmed by electrocardiographic monitoring.
The decreased pulse rate at comparable oxygen
demands reflects an improved oxygen pulse, which
is indicative of an increased cardiovascular effi-
ciency.

These findings cannot be generalized to all
post-infarction patients. Those with irreversible
myocardial restriction from extensive scarring or
fibrosis would not be expected to respond to phys-
ical conditioning. For example, one patient
trained for 6 months and increased his daily ac-
tivity tremendously. He claimed that he felt
better throughout the conditioning. When he
was re-evaluated, no differences in his cardiovas-
cular adjustments during identical levels of phys-
ical stress were detected (Figure 4), indicating
that he had lost the abilty to gain a conditioning
response, His systolic blood-pressure response
was of a lower magnitude than that observed in
the other man and the pulse-pressure remained
narrow throughout the test. Despite this limita-
tion, he was able to perform the entire test. The

Tavin 8. All of the training cardiacs increased the duration of the test performance following training and only one
stopped early. No changes in the mean duration were observed when the sedentary cardiacs were retested. Eleven
of the 12 sedentary controls completed the second evaluation.

Duration of test
(min)

Training cardiacs
Test 1 Test 2

12 5 --
1s 5
18 < il

Sedentary cardiacs Sedentary controls

Test 1 Test 2 Test 1 Test 2
3 4 a+ =
5 5 4 1
4 3 8 aoe





Taxue 1, The groups were closely matched fot age, height and weight.
Weight (ke)

N Age Height (em) Test 1 Test 2
Training cardiacs. 12 48.1 176.0 77.5 76.8
Sedentary cardiacs_ 12 47,1 173.9 76.1 75.7
Sedentary controls. - 12 48.4 178.3 76.9 80.0

different during the second evaluation in the
training cardiacs. Before physical conditioning
was initiated, their responses were similar to those
of the sedentary cardiacs, but 8 months later,
the determinations were more near those observed
in the sedentary controls.

Initially, the resting pulse rates were nearly
identical for each group (Table 2). ight
months later, the mean pulse rates were lower
in those cardiacs who had exercised, but were
unchanged in the two sedentary groups. A sim-
ilar pattern was observed during standing.

C. Responses During Treadmill Walking.

1. Systolic Blood Pressure.

procedure in the cardiacs who had exercised,
but unchanged in the two sedentary groups.
There was no significant interaction between
the two sedentary groups, indicating that the
presence of disease did not alter the cardiacs’
ability to adjust to the physical stress.

2. Diastolic Blood Pressure.

Again, the training cardiac had decreased
diastolic blood-pressure values (P 0.05) dur-
ing the second test, whereas the diastolic
pressures of the sedentary groups had de-
terminations which approximated those re-
corded during the first test (Figure 2). There
was no significant interaction between the

During the initial test, the systolic blood-
pressure response was similar in each group
at comparable levels of energy demand (Fig-
ure 1), Eight months later, the mean values
were lower P 0.05) throughout the testing

first and second tests of the two sedentary
groups. The sedentary cardiacs had slightly
higher diastolic blood pressures during the
tests than did either of the other two groups
of men.

Taste 2. Blood pressure and pulse rate decreased during rest and standing in the cardiacs who trained, but remained
essentially unchanged in the two sedentary groups
Blood pressure mm (Hg)
Supine Standing Supine Standing
N Test 1 Test 2 Test 1 Test 2 Test 1 Test 2 Test 1 Test 2

Pulse rate

‘Training cardiacs._.. 12 134/85 130/83 133/89 126/86 68 61 83 67
Sedentary cardiac: 12 136/91 140/90 139/85 139/94 7 70 82 83
Sedentary controls... 12 124/83 130/82 128/87 138/87 72 73 87 86

TRAINING CARDIACS

SEDENTARY CARDIACS SEDENTARY CONTROLS

3
3 vs. x
= B os, TRAINING CARDIACS SEDENTARY CARDIACS SEDENTARY CONTROLS
& Mss. # 10s
8 E
iss. 8 55, GO
g 2 =n.
Sus on Sa
g 3 “seen ——
* 135. 2 zs. cos wie
Fo tea a
135- PTO TTT ro Lee ee ee,
SPT TTS TTT ek Th Time fe ainaten |? on

Fieure 1, There was a significant decrease in the level

of systolic blood pressure following physical condi- Fieure 2, Significant decreases in diastolic blood pres-

tioning in the training cardiacs, whereas no differ-
ence was observed with retesting in either sedentary
group. hTe response of the sedentary cardiacs was
similar to that observed in the sedentary controls.
(The values represent the mean determination for
12 subjects.)

sure were observed in the training cardiacs, whereas
no differences occurred in either sedentary group.
The sedentary cardiacs consistently had higher dias-
tolic-blood-pressure determinations than the other
two groups, (All values represent the mean deter-
minations for 12 subjects.)


200
170
140

N10

80.
150

120
90
60

He

BLOOD PRESSURE

PULSE RATE

MEIN MINUTES

Figure 4, A 48-year-old white man was evaluated before
and after 6 months of physical conditioning. No
alterations were observed in his functional cardio-
vascular adaptations following the training, indi-
cating that he had lost the ability to be recondi-
tioned.

pulse-rate responses during both procedures were
like those observed in the sedentary men.

The test may be of value if employed peri-
odically for evaluating the functional adjustments
of cardiac patients. The quality of the physio-
logical responses may indicate that a patient has
limitations even though he is nonsymptomatic.
One patient was observed approximately 1 week
before suffering a second myocardial infarction.
During the initial evaluation, his resting and
standing blood pressures and pulse rates were
within normal limits. During walking, the pulse
pressure remained narrow and the pulse rate rose
steeply reaching 175/min at an oxygen intake
only five times that of the resting metabolic state
(Figure 5). No electrocardiographic abnormali-
ties were recorded. These adjustments were
definitely pathological and indicated that the
patient had very little myocardial reserve. One
year later, however, his cardiac reserve had been
largely restored. The systolic blood pressure in-
creased out of proportion to that usually ob-
served at comparable levels of physical stress;
the diastolic pressure rose slightly and remained
modestly elevated; the pulse-rate rose in a more
usual fashion. In addition, the patient did more
work without any indication that he had reached
his maximum capacity. Thus, the data from the
first test indicated that this patient was not a
satisfactory candidate for physical conditioning;

200
2170
£140

110

80
150

120
90
60

BLOOD PRESSURE

RATE

PULSE

Fieure 5. A 36-year-old white man was evaluated ap-
proximately 1 week before suffering a second myo-
eardial infarction. His blood-pressure and pulse-
rate responses were pathological and indicative of
poor cardiovascular reserve. When evaluated 1 year
later, his blood-pressure adaptation was consistent
with a hypertensive response and the pulse-rate
changes were essentially normal. These findings
indicated that he had regained some myocardial
reserve.

after he convalesced further, a second evaluation
showed him to have a good capacity for physical
training.

Vv. Summary.

Thirty-six men, twenty-four with well-docu-
mented episodes of myocardial infarction and
twelve presumably healthy, performed a work-
capacity test while sedentary. All of them were
re-evaluated 8 months later after 12 of the cardiac
patients had participated in a physical-condition-
ing program and the remainder had remained
sedentary. There were significant training effects
in the exercising cardiacs as reflected by the
systolic and diastolic blood-pressures and pulse-
rates during rest, standing and comparable levels
of energy expenditure. No differences were ob-
served between tests in either the sedentary
cardiac or sedentary healthy men. The response
to physical stress was similar in cardiacs to that
observed in the healthy men, indicating that the
presence of disease did not necessarily affect the
physiologic response of the subjects.


AM 66-17

PROBLEMS IN AEROMEDICAL CERTIFICATION

Cardiovascular Response to Exercise Following

Myocardial Infarction

J. Naughton, M.D.
K. Shanbour, B.S.
R. Armstrong, M.S.

J. McCoy
M. T. Lategola, Ph.D.
Approved by Released by
Bll Bile [USage€ 0
J. Roserr Diniz, M.D. P. V. Srecun, M.D.
Curer, Crvin ArromepicaL InstTrruTE FeprraL Air Surcron
June 1966

FEDERAL AVIATION AGENCY
Office of Aviation Medicine



REFERENCES

1, Navanton, J., SeveLrus, G., and Bake, B,: Physi-
ological Responses of Normal and Pathological Sub-
jects to .a Modified Work Capacity Test. J. Sports
Med., 3:201, 1963,

2. Hencersrein, H. K., Hirscx, E. Z, Aten, W. ©. Ly
Porster, S., and ZvucKER, N.: Reconditioning of the
Coronary Patient: A Preliminary Report. In Coro-
nary Heart Disease, p. 448, Likoff, W., and Moyer,
J. HL, eds, New York: Grune and Stratton, 1963.

3, Recunrrzer, P.A., YUHASz, M. 8., Proxarp, H. A., and
Lercoz, N. M.: The Effects 0 fa Graduated Exercise
Program on Patients with Previous Myocardial In-
farction. Canad. Med. Assoc. J, 92:858, 1965.

4, Barks, B., and Wane, R. W.: Experimental Study of
“Physical Fitness” of Air Force Personnel. U.S.
Armed Forces Med. J., 10:675, 1959.

ot

. NauaHron, J., and Naate, F,: Peak Oxygen Intake
During Physical Fitness Program for Middle-Aged
Men, J.A.M.A., 191:899, 1965.

Ficure 1. There was a significant decrease in the
level of systolic blood pressure following physical con-
ditioning in the training cardiacs, whereas no difference
was observed with retesting in either sedentary group.
‘The response of the sedentary cardiacs was similar to
that observed in the sedentary controls, (The values
represent the mean determination for 12 subjects.)

Ficure 2. Significant decreases in diastolic blood pres-
sure were observed in the training cardiacs, whereas
no differences occurred in either sedentary group. The
sedentary cardiacs consistently had higher diastolic
blood-pressure determinations than the other two groups.
(All values represent the mean determinations for 12
subjects. )

Ficure 3. The pulse rate was 12 to 20 beats per minute
lower throughout the test following the physical con-
ditioning. Retesting did not influence the pulse-rate in
either sedentary group. ‘The adaptions of the two
sedentary groups were quite similar throughout the tests.
(All values represent the mean determination for 12
subjects.)

Froure 4. A 48-year-old white man was evaluated be-
fore and after 6 months of physical conditioning. No
alterations were observed in his functional cardiovascu-
lar adaptions following the training, indicating that he
had lost the ability to be reconditioned.

Figure 5. A 36-year-old white man was evaluated ap-
proximately 1 week before suffering a second myocardial
infarction. His blood-pressure and pulse-rate responses
were pathologogical and indicative of poor cardiovscular
reserve. When evaluated 1 year later, his blood-pressure
adaption was consistent with a hypertensive response
and the pulse-rate changes were essentially normal.
These findings indicated that he had regained some
myocardial reserve.

67-3017



FOREWORD

A major question in aviation medicine concerns the aeromedical certifica-
tion of airmen with a history of myocardial infarction. Cardiac-rehabilita-
tion research has recently been initiated and advanced on a national scale
with very promising results. Return to full duties without symptoms has
been found possible. Many individuals attain a better cardiovascular status
than they had before their “heart attacks.”

A return to full duty is important for the economic and emotional well-
being of each airman concerned. Aviation safety can be improved by rehabili-
tation of these aviation personnel, development of the optimum means of
assessing each airman to determine his qualifications for return to full duties,

and by an exercise program to prophylactically reduce the prevalence of
heart disease.

The work reported here was supported in part by PHS Research Grants
No. HE-06286-05, No. 5T1-GM-108, andNo. FR-00005-04 and AM 66-5
(Phys.2). The work was performed with the cooperation of the Oklahoma
University Medical Center and the active participation of the following
staff members of the Center: John Naughton, M.D., R. Armstrong, M.S.
and J. McCoy.

Qualified requestors may obtain Aviation Medical Reports from Defense Documentation
Genter. The general public may purchase from Clearinghouse for Federal Scientific
and Technical Information, U.S. Dept. of Commerce, Springfield, Va. 22151


PROBLEMS IN AEROMEDICAL CERTIFICATION

I, Introduction.

An important question for the clinician is
whether or not a myocardial infarction neces-
sarily impairs the capacity of the heart for work.
Many physicians restrict indefinitely the physical
activity of their post-infarction patients. Others
prescribe physical training or conditioning. The
present study was undertaken to ascertain differ-
ences, if any, between post-infarction patients
and healthy subjects with respect to cardiovas-
cular responses to the demands of physical exer-
tion and to test the ability of post-infarction
patients to undergo physical conditioning.

II. Methods and Materials.

Thirty-six men, twenty-four who had recovered
from well-documented episodes of myocardial in-
farction occurring within 2 to 15 months of the
study and twelve who were apparently in good
health, were studied. They were all inially classi-
fied as sedentary because, although they were en-
gaged in their usual occupational and recreational
activities, they did not participate regularly in
sports or physical exercise. After the initial
period of evaluation, 12 of the postcoronary pa-
tients volunteered for a physical conditioning
program, The other 12 and the 12 presumably
healthy men remained “sedentary.” Each group
of 12 subjects was matched as nearly as possible
for age, height, and weight.

All of the subjects were tested and retested in
the same manner. Blood pressure was deter-
mined by the auscultatory method durihg rest,
standing, and the last half of each minute of
walking. Pulse rate was recorded simultane-
ously with a 15-second electrocardiographic tra-
cing and by a 15-second auscultatory count de-
termined concurrently with the blood pressure.
All measurements were monitored by the same
observer.

Walking was performed on a motor-driven
treadmill. Each subject performed a test, meas-
ured by the Douglas-Haldane technique, de-
signed to impose energy demands no greater
than seven time those of the resting metabolic

state. A subject began the walk on a level grade
at 2.0 mph. The speed was held constant while
the treadmill bed was elevated 3.5% every 3
minutes. The test was terminated after 18 min-
utes or earlier if the subject developed chest pain,
claudication, or severe dyspnea.

The physical conditioning was conducted under
medical supervision. The “training cardiacs” en-
gaged three times a week in am hour-long med-
jcally-supervised exercise session consisting of
competitive games, calesthenics, and noncompeti-
tive jogging. Each subject gradually increased
his level of energy expenditure.

In the statistical analysis, the training cardiac
patients served as their own controls. Their re-
sponses before and after training were compared.

The twelve healthy men served as a control
group for the sedentary cardiacs. Their responses
during each test were evaluated to determine if
a significant interaction occurred between the
groups. The responses within a group to similar
amounts of physical exercise were compared to
determine whether or not repeating the procedure
was accompanied by an altered physiological re-
sponse.

Since all men did not complete the entire.
standard testing procedure, the statistical an-
alysis was limited to those measurements recorded
during the first 12 minutes of walking. Systolic
and diastolic blood-pressure measurements were
treated independently in the analysis.

III. Results.
A. Group Characteristics.

The three groups were almost ideally matched
for age, height, and weight (Table 1). Very
little change in mean body weight was observed
in any of the groups during the study.

B. Cardiovascular Responses During Rest and
Standing.

Consistently lower values were recorded’ for
the systolic and diastolic blood-pressure in the
sedentary controls than for the sedentary car-
diacs (Table 2). These same values were slightly