Duration of the Hemodynamic Effects of 6 Weeks Repeated Moderate
Aerobic Exercise after Its Cessation
Midori Tanaka
1 a
, Motoaki Sugawara
1
, Yasuo Ogasawara
2
, Tadafumi Izumi
1
,
Kiyomi Niki
3
and Fumihiko Kajiya
2
1
Faculty of Health Care Sciences, Himeji Dokkyo University, Himeji, Japan
2
Department of Medical Engineering, Kawasaki University of Medical Welfare, Kurashiki, Japan
3
Biomedical Engineering Department, Tokyo City University, Tokyo, Japan
Keywords: Moderate-intensity Exercise, Cardiopulmonary Exercise Test, Anaerobic Threshold, Respiratory
Compensation, Cardiac Contractility.
Abstract: Purpose: We investigated changes in hemodynamic parameters at one-week intervals for 6 weeks after the
cessation of the aerobic exercise. Methods: A total of 20 young healthy volunteers were recruited. Using
ultrasonic diagnostic equipment, we measured wave intensity (WI) in the carotid artery. The maximum value
of WI during a cardiac cycle (W
1
) increases with an increase in Peak dP/dt. The exercise sessions were 30
min in duration on the bicycle ergometer. Subjects were asked to make an effort to maintain the heart rate
during the session at anaerobic threshold (AT) point determined during the pre-exercise cardiopulmonary
exercise testing (CPET). Exercise sessions were conducted three times per week over a period of 6 weeks,
and then stopped. After the cessation of the exercise sessions, WI was measured during CPET at one-week
intervals for six weeks. Results: The work rate (WR) at AT point and at RC point, V
O2
at RC point increased
and remained increased significantly up to 2 weeks after the cessation of the exercise. Oxygen consumption
(V
O2
) at AT point also increased, but remained increased significantly only up to 1 week after. RC point W
1
increased and remained increased significantly up to 1 week after.
1 INTRODUCTION
Aerobic exercise has been reported to be one of the
most effective methods to keep one’s health (Racil et
al., 2016) (Ozaki et al., 2015) and to help prevent
cardiovascular disease (Pantelic et al., 2013). Li J et
al. (Li and Siegrist, 2012) reported that high level of
leisure time physical activity had a beneficial effect
on cardiovascular health by reducing the overall risk
of incident coronary heart disease (CHD) and stroke
among men and women by 20% to 30%, while
moderate level of occupational physical activity
might reduce 10% to 20% risk of cardiovascular
disease. However, it is not well documented how long
the effects of exercise continue after its cessation. We
investigated changes in hemodynamic parameters at
one-week intervals for six weeks after the cessation
of the aerobic exercise.
a
https://orcid.org/0000-0002-1730-5594
2 METHOD
2.1 Noninvasive Measurements of
Wave Intensity
Wave intensity (WI) is a novel hemodynamic index,
which is defined as
WI = (dP/dt)·(dU/dt) (1)
at any site of the circulation, where dP/dt and dU/dt
are the derivatives of blood pressure and velocity with
respect to time, respectively. WI was obtained from
the carotid artery using a color Doppler system for
blood velocity measurement combined with an echo-
tracking system for detecting vessel diameter
changes. The vessel diameter changes were
automatically converted to pressure waveforms by
calibrating its peak and minimum values by systolic
and diastolic brachial blood pressures. The WI shows
two sharp positive peaks (Niki et al., 2002). The first
Tanaka, M., Sugawara, M., Ogasawara, Y., Izumi, T., Niki, K. and Kajiya, F.
Duration of the Hemodynamic Effects of 6 Weeks Repeated Moderate Aerobic Exercise after Its Cessation.
DOI: 10.5220/0008073501530156
In Proceedings of the 7th International Conference on Sport Sciences Research and Technology Support (icSPORTS 2019), pages 153-156
ISBN: 978-989-758-383-4
Copyright
c
2019 by SCITEPRESS Science and Technology Publications, Lda. All rights reserved
153
peak W
1
appears in early phase of LV ejection
(Figure. 1). The magnitude of W
1
significantly
correlates with the maximum rate of LV pressure rise
which is a conventional index of contractility (r =
0.74, P < 0.001)(Ohte et al., 2003).
2.2 Cardiopulmonary Exercise Testing
(CPET)
Graded cardiopulmonary exercise test (CPET) was
performed by using a bicycle ergometer combined
with a computerized breath-by-breath expiration gas
analyzer system. The system measured tidal volume,
oxygen concentration and carbon dioxide
concentration, and automatically displayed oxygen
consumption (V
O2
), carbon dioxide production (V
CO2
),
minute ventilation (V
E
), V
E
/V
O2
, V
E
/V
CO2
, partial
pressure of end-tidal carbon dioxide (PETCO
2
),
partial pressure of end-tidal oxygen (PETO
2
),
anaerobic threshold (AT), and respiratory
compensation point (RC).
2.3 Subjects
We studied 20 healthy young volunteers (9 men, 11
women, mean age 20.6 ± 0.5 years, age range 19 23
years). We obtained informed consent from all the
subjects. The study was approved by the Himeji
Dokkyo University Research Ethics Committee and
conformed with guidelines of the Declaration of
Helsinki.
2.4 Experimental Protocol
The exercise sessions were 30 min in duration on the
bicycle ergometer. Subjects were asked to make an
effort to maintain the heart rate during the session at
anaerobic threshold (AT) point determined during the
pre- exercise CPET.
Bicycle work rate (WR) was quantified in Watts
(W). The initial work rate was 20 W and increased by
20 W every 1 minutes until limitation. The limitation
criteria for the establishment of peak Vo
2
included a
plateau in the Vo
2
with increasing WR, attainment of
HR to 158 bpm ((220 bpm age) x 0.8) and
Figure 1: Representative recordings of wave intensity
obtained from the carotid artery of a normal subject. Blood
pressure waveform, blood velocity waveform, wave
intensity waveform, and ECG are shown in order from the
top. The first peak of wave intensity (W1) appears in early
ejection phase.
attainment of fatigue to the maximum, or
impossibility of continuing exercise. Electro-
cardiogram was continuously monitored. The blood
pressure was measured approximately every 30 s.
Exercise sessions were conducted three times per
week over a period of 6 weeks, and then stopped.
After the cessation of the exercise sessions,
measurements were performed during CPET at one-
week intervals for six weeks in the same manner as
the exercise session. We measured W
1
Vo
2
, and
Vco
2
during CPET, and analyzed at AT point and RC
point.
2.5 Statistical Analysis
The obtained data were presented as mean ± SD.
Repeated measures ANOVA, followed by Bonferroni
test when necessary, was used to evaluate the changes
after the cessation of the exercise. A value of p < 0.05
was considered statistically significant.
Table 1: Baseline data of the subjects.
icSPORTS 2019 - 7th International Conference on Sport Sciences Research and Technology Support
154
3 RESULTS
After 6-weeks exercise training, Ps, Pd and HR at AT
and RC point did not change significantly.
However, WR at AT point increased and
remained increased significantly up to after 2 weeks.
Vo
2
at AT point also increased, but remained
increased only up to 1 week after (Figure. 2).
W1 at RC point increased and remained increased
significantly up to after 1 week. WR and Vo
2
at RC
point increased and remained increased significantly
up to 2 weeks after (Figure. 3).
Figure 2: Changes in indices at anaerobic threshold (AT)
point after the cessation of the 6 weeks exercise. Values are
compared with those before the commencement of the
exercise. mean ± SD.
Figure 3: Changes in indices at Respiratory compensatory
(RC) point after the cessation of the 6 weeks exercise.
Values are compared with those before the commencement
of the exercise. mean ± SD.
4 DISCUSSION
The anaerobic threshold (AT) is an index used for
estimating exercise capacity. During the initial
aerobic phase of CPET, which lasts until 50 60% of
Vo
2
max is reached, minute ventilation (VE)
increases linearly with Vo
2
. This indicates that
aerobically produced Co
2
in the muscles blood lactate
levels do not change substantially during this phase,
since muscle lactic acid production is minimal
(Takano, 2000).
In this study of 6 weeks exercise, Vo
2
at AT point
increased and remained increased significantly up to
1 week after the cessation of the exercise. WR at AT
point also increased and remained increased up to 2
weeks after the cessation of the exercise. RC point is
an indicator that exercise intensity has reached the
physiological maximum level to start compensation
for acidosis by increasing Co
2
excretion. Therefore,
RC point ascent indicates increase in exercise
tolerance. In our study, RC point WR, and RC point
Vo
2
increased by the 6 weeks exercise and remained
increased significantly up to 2 weeks after the
cessation of the exercise. RC point W
1
(cardiac
contractility index) also increased and remained
increased 1 week after.
5 CONCLUSIONS
In healthy young subjects, W
1
, WR and Vo
2
were
increased by intermittent, moderate-intensity aerobic
exercise for 6 weeks. The effects of the exercise
continued up to 2 weeks after its cessation.
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