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AltayeKZ, etal. BMJ Open Sp Ex Med 2019;5:e000524. doi:10.1136/bmjsem-2019-000524 1
Open access Original article
Effects of aerobic exercise on thyroid
hormonal change responses among
adolescents with intellectual disabilities
Kefelegn Zenebe Altaye, 1 Soumitra Mondal,2 Kesatie Legesse,2
Mahmud Abdulkedir3
To cite: AltayeKZ, MondalS,
LegesseK, etal. Effects of
aerobic exercise on thyroid
hormonal change responses
among adolescents with
intellectual disabilities. BMJ
Open Sport & Exercise Medicine
2019;5:e000524. doi:10.1136/
bmjsem-2019-000524
Accepted 16 May 2019
1Department of Sport Science,
Wollo University, Dessie, Ethiopia
2Department of Sport Science,
Mekelle University College of
Natural and Computational
Sciences, Mekelle, Ethiopia
3Department of Microbiology &
Immunology, Mekelle University,
Mekelle, Ethiopia
Correspondence to
Dr Kefelegn Zenebe Altaye;
kefelegnmu@ gmail. com
© Author(s) (or their
employer(s)) 2019. Re-use
permitted under CC BY-NC. No
commercial re-use. See rights
and permissions. Published by
BMJ.
What is the new nding?
►Aerobic exercise increases the concentration of
triiodothyronine and tetraiodothyronine in the blood,
which have an exciters effect on the central nervous
system, leading to academic improvement and suc-
cess of adolescents with intellectual disabilities.
►Aerobic exercise can decrease the concentration of
thyroid stimulating hormone in the blood of adoles-
cents with intellectual disabilities.
►Aerobic exercise can maintain the equilibrium in thy-
roid and thyroid stimulating hormone homeostasis in
adolescents with intellectual disabilities.
What is already known?
►Aerobic physical exercise has a great impact on
energy expenditure, reduces body fat mass and im-
proves the lung function of individuals with intellec-
tual disabilities.
►Aerobic physical exercise increases the metabolism
of lactic and fatty acids and affects changes in hor-
monal concentrations in adolescents with intellectu-
al disabilities.
►Aerobic physical exercise plays a signicant role in
increasing brain function, which is linked to cogni-
tive development and academic achievement in ad-
olescents with intellectual disabilities.
ABSTRACT
Objective We aimed to investigate the impact of a
16-week aerobic exercise programme on the changes
in the plasma level concentration of thyroid hormones in
adolescents with intellectual disabilities.
Methodology Using purposive sampling, a total of 36
adolescents with intellectual disabilities were selected to
participate in the study. The training programme consisted
of 16 weeks of moderate-intensity aerobic exercises
at an intensity of 45–75 hours. These exercises were
performed in three sessions a week, and each session
took 30–45 min: 10 min warm-up, 15–30 min main aerobic
workout and 5 min cool-down exercises. The plasma levels
of triiodothyronine (T3) and tetraiodothyronine (T4) and of
thyroid stimulating hormone were measured before and
after 16 weeks of aerobic exercise intervention.
Results After 16 weeks of intervention, a signicant
change was observed in the plasma level concentration
of thyroid (T3 and T4) and thyroid stimulating hormones
(p<0.05) in the group treated with aerobic exercise.
Conclusion We concluded that aerobic exercise had an
impact on the change in the plasma level concentration of
thyroid and thyroid stimulating hormones in adolescents
with intellectual disabilities.
INTRODUCTION
Intellectual disability (ID) is characterised
by significant limitations in cognitive func-
tioning, adaptive behaviour, and conceptual,
social and practical skills. In addition, when
compared with their typically developed
peers, persons with ID are more likely to be
obese, less likely to be physically active and are
twice as likely to develop a chronic disease.1
Also, compared with their normal peers,
they are more limited in how well and how
quickly they can learn, and score the lowest
and more likely to repeat each class level.2
The percentage of individuals with ID who
completed primary education is significantly
lower than persons without disabilities,3 and
often they have cognitive problems associated
with carrying out exercises.4 The worldwide
and Ethiopian prevalence of ID is 1.3%.5
ID is associated with lower levels of thyroid
hormones. In relation to these, thyroid
hormone deficiency during fetal and post-
natal development may cause retarded brain
maturation, intellectual deficits, and in some
cases neurological impairments.6 However,
proportional secretion of tetraiodothyronine
(T4) and triiodothyronine (T3) accelerates
growth and stimulates activities in the nervous
system.7 Therefore, thyroid hormones are
important for normal brain and nervous
system development and function.8
Previous studies reported that aerobic
exercise increases total serum T3 and
T4.9 10 Consequently, a moderate-intensity
level of exercise can increase T4 concentra-
tion in the blood.11 Aerobic exercise has been
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2AltayeKZ, etal. BMJ Open Sp Ex Med 2019;5:e000524. doi:10.1136/bmjsem-2019-000524
Open access
Table 1 Demographic characteristics of adolescents with
intellectual disabilities in the aerobic and control groups
Variables
Aerobic group Control group
Mean SD Mean SD
Age (years) 14.44 1.199 14.389 1.145
Height (metre) 1.50 0.042 1.49 0.046
Mass (kg) 49 5.89 48.16 6.148
associated with a progressive decrease or an improvement
in serum thyroid stimulating hormone (TSH).12 On the
contrary, 12 weeks of aerobic exercise had shown an insig-
nificant change in the plasma level of TSH, T3 and T4
hormones among sedentary women. These hormonal fluc-
tuations are dependent on the intensity, duration and type
of exercise and on the individual’s age,13 and still contradic-
tory results were seen on the effects of aerobic exercise on
thyroid hormonal change responses.14 Little information
has been seen on the effects of aerobic exercises on thyroid
hormone change responses in adolescents with ID.
Therefore, we designed the present study to investigate
the effects of 16 weeks of aerobic exercises on hormonal
change concentration in adolescents with ID. This was
done using quasi-experimental research design and
using T3, T4 and TSH as outcome markers. Based on
the findings of the study, the lifestyle and participation
of adolescents with ID in social and economic activities
might be enhanced to support their family and their
country at large. The study may also serve as a spring-
board for those who are interested to conduct further
similar research in the area, especially by including diet
as one of the variables, among others.
MATERIALS AND METHODS
Study design
A quasi-experimental design was employed to investigate
the effects of 16 weeks of aerobic exercise on thyroid
hormonal change responses in adolescents with ID in
Dessie-Kombolcha.
Sample and sampling technique
The study has two groups: experimental and control
groups. The participants were free from epilepsy and
autism disorders. The total number of the population
was 72, and in the current study 36 of them, which were
50% of the total population, were purposively taken as
a sample and were randomly selected and placed in the
experimental and control groups. All participants were
randomly divided into two groups, control and experi-
mental groups, with 18 participants each. After explaining
the purposes of the study and the privacy of informa-
tion to the participants and their guardians, they were
completely satisfied to cooperate and signed a consent
agreement to participate in this study. The participants
of the experimental group were invited to take orien-
tation about how to execute planned aerobic exercises
before the first day of the actual training period, while
the participants of the control group committed to not
participate in any exercise except their formal schools
physical exercise periods during the 16-week period of
the study.
Blood analysis
In order to measure the plasma level of TSH and thyroid
hormones (T3 and T4), blood samples were drawn from
adolescents 48 hours before the first training session and
48 hours after the last training session. Samples of blood
specimen were collected in sitting position by qualified
laboratory technicians. Six millilitres of venous blood
were drawn from each participant’s vein pretest and post-
test. The blood samples were drawn into tubes containing
an anticoagulant. All blood samples were preserved in a
frozen condition at −20°C and were conserved until anal-
ysis. All variables were measured by ELISA using Autobio
laboratory kits.
Training protocol
The training programme consisted of 16 weeks of
moderate-intensity aerobic exercises and was conducted
after receiving parental consent. These exercises were
performed three sessions a week, and each session took
30–45 min. Each session consisted of 10 min of warm-up
exercises, 15–30 min of main aerobic workout and 5 min
cool-down exercises. Study participants and their parents/
guardians have a complete right to reduce and stop the
exercise, and it is their obligation to inform the fitness
training programme personnel should any symptoms
develop. Therefore the fitness trainer can reduce or stop
the exercise programme should any symptoms develop
and will indicate that this was done for the benefit and
safety of the participants. Moreover the participants have
an absolute right to withdraw from the programme by
themselves or with the help of their parents/guardians.
Statistical analysis
In this study, independent t-test was used to compare
intergroup variations between experimental and control
groups on the effects of 16 weeks of aerobic exercise on
thyroid hormone change responses in adolescents with
ID. Significance level was considered at p≤0.05.
RESULTS
Thirty-six adolescents with ID were studied. Table 1 shows
the mean and SD of age, height and mass of adolescents
with ID. For adolescents with ID treated with aerobic
exercise, the mean (SD) age, height (in metre) and mass
(in kilogram) were 14.44 (1.199), 1.50 (0.042) and 49
(SD=5.89), respectively, and for the control group the
mean (SD) age, height and mass were 14.389 (1.145),
1.49 (0.046) and 48.16 (6.148), respectively.
Table 2 shows the mean and SD score in hormonal
concentration change responses between the experi-
mental and control groups using independent t-test in T3
(, p=0.0005), the mean and SD score in hormonal change
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AltayeKZ, etal. BMJ Open Sp Ex Med 2019;5:e000524. doi:10.1136/bmjsem-2019-000524
Open access
Table 2 Average and SD of thyroid hormone change
responses in adolescents with intellectual disabilities
between the control and experimental groups using
independent t-test
s/n Variables Group Mean±SD t value df P value
1 T3 Aerobic 1.713±0.224 4.953 34 0.005*
Control 1.421±0.11
2 T4 Aerobic 8.349±1.043 5.253 34 0.0001*
Control 6.617±0.931
3 TSH Aerobic 1.097±0.157 −2.971 34 0.0001*
Control 1.413±0.423
*The mean difference is signicant at p<0.05.
T3, triiodothyronine; T4, tetraiodothyronine; TSH, thyroid stimulating
hormone; s/n, serial number.
responses between the experimental and control groups
using independent t-test in T4 (t=5.253, p=0.0001), and
the mean and SD score in hormonal change responses
between the experimental and control groups using
independent t-test in TSH (t=−2.971, p=0.0001).
DISCUSSION
We aimed to investigate the effects of aerobic exercise on
thyroid and thyroid stimulating hormonal concentration
change responses in adolescents with ID. Based on the
findings of the study, the aerobic exercise intervention
had shown a significant change response in the plasma
levels of TSH and thyroid hormones (T3, T4) when
compared with the control group.
The results of this study are consistent with previous
studies9–12 15 that reported serum TSH was found signifi-
cantly decreased and T3 and T4 significantly increased
with aerobic exercise intervention. Acute aerobic exer-
cise performed at moderate intensity induced significant
increases in total serum T3 and T4. This confirms that
aerobic exercise may enhance the thyroid hormone
concentration in the serum. However, the present study
was in contrast to previous studies8 16 17 that reported
aerobic exercise had no significant effect on thyroid
hormone concentration. These variations might be due
to the specific characteristics of students with ID. Individ-
uals with ID have thyroid hormone deficiency18 and have
lower aerobic fitness levels compared with their equiva-
lent able peers.1 2 19 Thus,20 confirmed that all these can
be improved by physical exercise.
In this study, significant improvements in T3, T4
and TSH in response to aerobic exercises might be
the specific characteristics of those adolescents with ID
and the methodological differences in the type, inten-
sity and frequency of the training protocol. Thus, the
researcher believed that 4 months of aerobic intervention
programme is possibly too long to achieve equilibrium in
thyroid and thyroid stimulating hormone homeostasis in
adolescents with ID.
Aerobic exercise has a number of physiological and
psychological impacts. It has a great impact on the growth
of new blood vessels in the brain, which increases cognitive
impairments,21 improves lung function in ID,22 increases
the efficiency of aerobic endurance,23 and increases T3
and T4 levels,11 which have an effect on the exciter nerve
cells of the central nervous system,24 leading to academic
improvement and success of students.25 Thus, aerobic
physical exercise has a therapeutic effect, and parents
can use it as a treatment to minimise the physiological
causes of cognitive impairment and improve the lifestyle
of adolescents with ID. Thus, adolescents with ID should
be motivated to undertake regular aerobic exercises to
enhance their participation in educational, social and
economic activities. An investigation on thyroid and
thyroid stimulating hormonal change responses in rela-
tion to adolescents with ID, which have been uncovered
by other researchers, should be considered a strength of
this study. The results of the study can be used as a spring-
board for those who are interested to conduct further
similar research work in this area, especially by including
diet as one of the variables, among others.
Limitations
The limitations of this study were the problem of working
with adolescents with ID and the lack of timely presence
of the study participants during the training sessions.
CONCLUSION
We concluded that aerobic exercises of moderate intensity
are an efficient method to change the plasma concen-
tration of thyroid and thyroid stimulating hormones in
adolescents with ID.
Acknowledgements The authors would like to acknowledge the study
participants and their parents/guardians. All of their teachers, training coaches and
school directors who helped in this study are greatly appreciated.
Contributors All authors made great contributions to the completion of the study.
MA participated in the methodology and data analysis. KL participated in the
sequence alignment and interpretation of data, and drafted the manuscript. KZA
contributed to writing the original draft and preparation. SM participated in writing
and review, sequence alignment, and editing of the manuscript.
Funding The authors have not declared a specic grant for this research from any
funding agency in the public, commercial or not-for-prot sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The experiment complied with the laws of ethical clearance
committee (HRERC), and the College of Health Science, Mekelle University
approved the study (ERC0775/2016). Informed consent was obtained from all
participants and their parents/guardians before testing and commencing the study.
The participants and their parents/guardians signed and conrmed their voluntary
agreement to full participation in this scientic training session project. With regard
to ethical conditions of the research, the researchers made sure that no one was
affected by this scientic study. Only 6 mL of blood was taken from the study
participants during each of the pretests and post-tests.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request.
Open access This is an open access article distributed in accordance with the
Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which
permits others to distribute, remix, adapt, build upon this work non-commercially,
and license their derivative works on different terms, provided the original work is
properly cited, appropriate credit is given, any changes made indicated, and the
use is non-commercial. See:http:// creativecommons. org/ licenses/ by- nc/ 4. 0/.
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