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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 3, May/June 2020
118
AFRICA
individuals enrolled in regular AE (
n
=
20), of whom the arterial
baseline pressures of 10 were evaluated for 24 hours after 48
hours of rest after their last exercise training; and in the other 10
subjects the PEH induced by an AE session was assessed. The
other 20 individuals enrolled in regular LE were randomised and
evaluated in the same way (Fig. 1).
Body mass was measured with a digital scale having a capacity
of 150 kg and an accuracy of 100 g (EKS
®
SUPER 9805). Height
measurement was performed with a compact stadiometer fixed
to the wall, and with a range of 0 to 2.0 m and an accuracy of
1 mm (Coats Corrente
®
BA1010).
The heart rate (HR) was measured in both groups at rest and
after a cardiopulmonary test. For this a cardiac monitor (Polar
®
model FT1) was used to collect resting HR. The HR recording
was made in the seated position for two minutes after a rest of
10 minutes; the lowest HR reached in this period was used. The
maximal HR was measured immediately after completion of the
cardiopulmonary test.
For evaluation of the maximum aerobic capacity (VO
2
max
), the
progressive treadmill test was applied following the Balke–Ware
protocol.
34
The maximal VO
2
was evaluated using an open-
circuit spirometry VO2000
®
ventilometer and an Inbramed
®
treadmill.
35,36
BP was measured at rest and after cardiopulmonary tests in
both groups. For the former, the BP was assessed three times
after 10 minutes of rest in a seated position at intervals of one
minute, and the result was taken as the mean value, while for
the latter, the BP was assessed immediately after completion of
the treadmill test with a stethoscope (Missouri
®
) and a manual
aneroid sphygmomanometer (Missouri
®
) with a precision of
2 mmHg.
The ABPM was started 48 hours after the last training
session to evaluate the baseline BP in the AE and LE groups.
To evaluate PEH, the ABPM was started immediately after
the exercise session. Three devices of the Meditech KFT
®
brand, model ABPM-04, were used. The BP cuff was worn on
the non-dominant arm. Subjects were instructed to maintain
their customary daily activities, not to exercise, and to relax
and unbend the arm during the recording interval for daytime
ABPM. ABPM data were accepted with more than 75% of the
measurements effectively taken. Individual BP measurements
were revised for missing and erroneous values.
For comparison purposes, data were distributed across
the waking period, which consisted of the mean BP of the
measurement made every 15 minutes during the periods of
the day when the individual was awake (07:00 to 23:00), and
the sleep period, during which the BP was measured every 30
minutes and the mean value taken when the individual was
asleep (23:00 to 07:00). The result for each hour was then the
average of the values recorded during that hour.
For the AE-PEH, each individual remained at rest in a seated
position for 15 minutes, then BP was measured three times with
a sphygmomanometer and stethoscope. Subsequently the test
exercise session was started, which consisted of collective water
aerobics with a duration of 50 minutes, comprising five minutes
of preparatory activity, 20 minutes of aerobic exercises at 75%
of reserve HR (RHR), 20 minutes of strength exercises, and five
minutes of stretching. The HR was monitored by a heart rate
monitor (POLAR
®
RS800) during the entire session. After the
experimental session, ABPM was used to record BP during the
following 24-hour period.
For the LE-PEH, each individual remained at rest in a seated
position for 15 minutes, then the BP was measured three times
with a sphygmomanometer and stethoscope. Subsequently the
test exercise session was started, which consisted of aerobic
collective gymnastics with a duration of 50 minutes, including
five minutes of preparatory activity, 20 minutes of aerobic
exercises at 75% of RHR, 20 minutes of resistance exercises,
and five minutes of stretching. HR was monitored by a heart
rate monitor (POLAR
®
RS800). After the experimental session,
ABPM was used to record the BP during the following 24-hour
period.
Statistical analysis
The Shapiro–Wilk test was used to evaluate the normality of
the numerical data. Data are presented as mean
±
standard
deviation. An unpaired
t
-test with Welch’s correction was used
to compare the cardiopulmonary response between AE and LE,
as well as the magnitude of PEH at the second, 12th and 24th
hours after the session.
Two-way ANOVA was used to compare PEH for the sessions
by time (second, 12th and 24th hour), as well as determine
interaction effects (session and time), followed by Bonferroni’s
post hoc
test. A 5% significance level was set. All statistical
analyses utilised Graph Pad Prism 7.0
Results
Table 1 shows the characteristics of the experimental groups.
There were no differences between the groups by age, body mass
index, peak VO
2
, or resting systolic BP (SBP) and DBP.
Table 2 shows the HR and BP responses to maximal effort
recorded after the cardiopulmonary test. The values of HR and
Table 2. Cardiovascular response to maximal effort in
the cardiopulmonary test in hypertensive subjects
trained in aquatic and land exercise
AE (
n
=
10)
LE (
n
=
10)
HR (bpm)
134 (124.9–143.9)
147 (136.5–157.3)*
SBP (mmHg)
160 (150.9–191.7)
162.5 (151.3–177.9)
DBP (mmHg)
80.0 (72.4–89.6)
90.0 (84.1–90.5)*
AE: aquatic exercise; LE: land exercise; HR: heart rate; SBP: systolic blood
pressure; DBP: diastolic blood pressure. *
p
< 0.05 when compared to AE.
Mann–Whitney test, data expressed in median and 95% confidence interval.
Table 1. General profile of the two hypertensive groups
LE-PEH
(n
=
10)
AE-PEH
(n
=
10)
LE
(n
=
10)
AE
(n
=
10)
Age (years)
67
±
3
64
±
3
65
±
3
70
±
2
BMI (kg/m²)
26.4
±
3.4 25.7
±
2.8 27.3
±
3.3 26.5
±
5.2
Peak Vo
2
(ml/kg/min)
23.4
±
3.4 22.6
±
2.1 25.7
±
4.7 24.8
±
3.4
Resting SBP (mmHg)
140
±
4.4 153
±
5.0 130
±
8.3 128
±
9.8
Resting DBP (mmHg)
85
±
4.3 90
±
5.6 82
±
4.2 81
±
8.1
Antihypertensive drugs (
n
)
2 (1–2)
1 (1–2)
2 (2–3)
1 (1–2)
Diuretic (%)
60
50
60
50
ACE inhibitor (%)
20
0
20
0
ARB (%)
80
80
60
80
AE-PEH: aquatic exercise PEH; LE-PEH: land exercise PEH; AE: aquatic
exercise; LE: land exercise; PEH: post-exercise hypotension; VO
2
; volume of
oxygen; BMI: body mass index; SBP: systolic blood pressure; DBP: diastolic
blood pressure; ACE inhibitor: angiotensin converting enzyme inhibitor; ARB:
angiotensin II receptor blocker. Data expressed as mean
±
SD.