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Journal of yroid Research
Volume , Article ID , pages
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Clinical Study
Influence of a Medium-Impact Exercise Program on
Health-Related Quality of Life and Cardiorespiratory
Fitness in Females with Subclinical Hypothyroidism:
An Open-Label Pilot Study
Andrea Garces-Arteaga,1Nataly Nieto-Garcia,1Freddy Suarez-Sanchez,1
Héctor Reynaldo Triana-Reina,1and Robinson Ramírez-Vélez2
1Departamento de Educaci´
on F´
ısica y Deporte, Universidad del Valle, Mel´
endez Cali, Colombia
2GrupoGICAEDS,FacultaddeCulturaF
´
ısica, Deporte y Recreaci´
on, Universidad Santo Tom´
as,
Carrera 9 N∘51-23, Bogot´
a, DC, Colombia
Correspondence should be addressed to Robinson Ram´
ırez-V´
elez; robin@hotmail.com
Received March ; Revised October ; Accepted October
Academic Editor: Noriyuki Koibuchi
Copyright © Andrea Garces-Arteaga et al. is is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Objective. To examine the inuence of a medium-impact exercise program (MIEP) on health-related quality of life (HRQoL)
and cardiorespiratory tness (VO2max) in females with subclinical hypothyroidism (sHT). Materials and Methods. We s e l e c ted
sedentary women with sHT (mean age: . (standard deviation: .) years). Participants carried out an MIEP consisting of weekly
sessions of minutes during weeks. Before and aer the exercise program HRQoL was assessed by the SF-v questionnaire,
and VO2max was evaluated by Rockport walk test. Results. Aer the -week intervention, the participants that performed an MIEP
showed improvements in HRQoL in most domains, particularly the vitality domain by points, the social functioning domain by
points, the mental health domain by points, and the mental component summary by points. One of the four domains within the
physical component summary (general health domain) showed signicant eect of the exercise intervention: points. Moreover,
the participants that performed exercise showed a higher VO2max (%; 𝑃 < 0.01). Conclusion. Aer weeks of medium-impact
exercise program, there were remarkable improvements in HRQoL in most domains. Moreover, this exercise program proved to
have a positive inuence on cardiorespiratory tness.
1. Introduction
Prevalence of subclinical hypothyroidism (sHT), dened
as elevated thyroid stimulating hormone (TSH) with free
thyroxine (fT) in the normal range, increases with age
aecting about % of individuals aged to years and
% of those aged or older [,]. Patients with sHT
are associated with increased prevalence of atherosclerotic
lesions and cardiovascular events [,]. Besides, thyroid
hormone deciency may also interfere substantially with
various aspects of physical, mental, and social well being
[] and many studies showed changes in functional status
(i.e., mobility limitation, disability, and poor tness level) in
patients with sHT [,].
On the other hand, the evidence for improvement of
psychiatric symptoms with hormonal treatment (levothy-
roxine) of OH and the use of triiodothyronine (T) to
potentiate the response to treatment of depressive disorders
suggests a direct relationship between thyroid hormones and
psychiatricsymptoms[,]. Neurobiological evidence seems
to corroborate the hypothesis of an organic basis of the
eects of thyroid hormone on the brain and on psychiatric
symptoms [].
Interventions for sHT have included pharmacologic ag-
ents (i.e., hormonal treatment), psychotherapy, alternative
therapies, and physical activity which can improve cardio-
vascular health, psychiatric symptoms, and health-related
Journal of yroid Research
quality of life (HRQoL) [,]. To date, few studies on
HRQoLinsubjectswithsHTinresponsetoexerciseprogram
have been reported [,].
It has been proved that regular exercise positively aects
the mechanisms of action associated with the physiologic
deterioration and transition from subclinical thyroid disease
[]. Several authors recommended exercise to be performed
within an intensity range of –% of maximum oxygen
consumption by VO2max. Nevertheless, more recent studies
emphasize the necessity of exploring the eects of intensity
[,]. Clinical thyroid disease is associated with changes
in the cardiovascular system, including changes in heart
rate during exercise. Considering this, we hypothesized that
medium-impact exercise program would provide a more ade-
quateexercisestimulusforimprovinganumberofmetabolic
factors in females at risk for thyroid disease. erefore, we
hypothesized that a medium-impact exercise program can
also improve HRQoL and cardiorespiratory tness in females
with sHT.
2. Materials and Methods
2.1. Subjects. From January to September ,
sedentary Colombian women with sHT (physical exercise
less than once a week) were referred to our hospital for
health examination (Servicio Medico Universidad del Valle).
Subjects studied were between and years of age, mean
age 43.1 ± 9.7 years. All patients with sHT were newly
diagnosed and were positive for both antithyroid peroxidase
(TPO-Ab) and antithyroglobulin (Tg-Ab) antibodies. e
diagnosis of sHT was established on the basis of the elevated
TSH levels and normal fT and fT values. In patients with
sHT, laboratory tests were performed – days before and
weeks aer the initiation of the training program. Obese
subjects (body mass index (BMI) >kg.m−2), smokers, and
individuals with hypertension, clinical detectable coronary
artery disease, and other diseases were excluded from the
study. None of the patients were taking any medicine, such
as estrogen supplements, T, diuretics, antihypertensive,
or hypolipidemic drugs. e University of Valle Research
Ethics Committee approved this study. Informed consent
was gained from all participants before the data collection
began.
2.2. Medium-Impact Exercise Program. Preparatory training
phase(weeks–):thepresentstudybeganwitha-week
preparatory phase of training to bring all participants up their
kcal/kg/wk goal. To accomplish this, all participants began
their exercise program at a selected intensity set at a heart
corresponding to –% of VO2max and a frequency of
times per week.
Implementation of medium-impact exercise program
(weeks –): exercise prescription was standardized to body
weight, and it was estimated that minutes per week of
moderate intensity exercise was equivalent to to kcal/kg
of body weight per week. Exercise intensity was dened
between % and % of VO2max. An aerobic dose of
kcal/kg per week was selected for the aerobic group. Par-
ticipants were weighed weekly to calculate their kcal/kg per
week target. American College of Sports Medicine equations
(ACSM) were used to estimate caloric expenditure rate and
time required per session []. e exercise prescription used
was established from the participants baseline exercise test
and corresponded to a speed and grade associated with an
upper intensity working level of % to % VO2max followed
by recovery level of % VO2max . Each session included a
min aerobic circuit training guided by an audio recording
(tropical and latin music). e entire workout lasted about
minutes that, depending on the number of exercise (
stations), were usually repeated three times. During and
minutes throughout the routine, participants were instructed
to check their pulse to ensure that they were working within
their target heart rate range. Each session was preceded
and followed by a gradual warm-up and cool down period,
both of minutes duration and consisting of walking and
light, static stretching (avoiding muscle pain) of most muscle
groups (upper and lower limbs, neck, and trunk muscles).
ecool-downperiodalsoincludedrelaxationandstretching
exercises. Resistance exercises were performed through the
full range of motion normally associated with correct tech-
niqueforeachexerciseandengagedthemajormusclegroups
(abdominal, dorsal, shoulder, and upper and lower limb
muscles). ey included exercise group circuit training (
repetitions of each) using barbells (– kg/exercise) or low-to-
medium resistance bands (therabands and balls). Each type of
exercise on the back was performed for min.
Adherence to the exercise program was encouraged by
the exercise trainer and the physician who supervised each
of the group sessions. Trainers were physical educators with
experience in developing and monitoring exercise programs
among clinical populations. In order to maximise adherence
to the training program, exercise classes consisted of relevant
activities for the group, – participants were accompanied by
music dancing and performed in a spacious, air-conditioned
room (: am). Each participant met with the study
dietician for nutrition assessment and counselling, and an
individualized nutrition intervention plan was developed
fromthebaselinefoodintakeassessment,participantpref-
erences, and the meal plan [].
2.3. Health-Related Quality of Life Assessment. e Colom-
bian standard version of the Medical Outcome Study Short-
Form Health Survey (SF- version ) is a questionnaire
comprising questionsgrouped into eight dierent domains
of health: physical functioning, role limitation due to physical
problems, bodily pain, general health perception, vitality,
social function, role limitation due to emotional problems,
and mental health. ese eight scales are further clustered
into the physical component summary (comprising physical
function, role-physical, bodily pain and general health) and
mental component summary (comprising vitality, social
function, role-emotional, and mental health) []. e quan-
tication of the mentioned dimensions is values varying from
to , where corresponds to “worse health” and to
“better health.”
Journal of yroid Research
T : Baseline characteristics in females with subclinical hypo-
thyroidism.
Variabl e Me an ( SD )
Age (years) . (.)
Weight (kg) . (.)
BMI (kg/m) . (.)
Waist circumference (cm) . (.)
Hip circumference (cm) . (.)
Systolic BP (mm Hg) . (.)
Diastolic BP (mm Hg) . (.)
Submaximal oxygen consumption by VO2max . (.)
Maximum heart rate (beats/min) . (.)
Total cholesterol (mg/dL) . (.)
Triglycerides (mg/dL) . (.)
HDL-C (mg/dL) . (.)
LDL-C (mg/dL) . (.)
Glucose (mg/dL) . (.)
TSH (mIU/L) . (.)
2.4. Cardiorespiratory Fitness Evaluation. Submaximal oxy-
gen consumption (VO2max) was assessed with the Rockport
walking test. During the test, heart rate was monitored
electronically using a Polar A- pulse meter (Polar Electro
Oy, Kempele, Finland). e cardiorespiratory tness was
calculated by VO2max via the ACSM equation []:
VO2max (mL ⋅Kg ⋅min−1)
= 132.853 − 0.0769 × weight − 0.3877
×height + 6.315 × 0 − 3.2649
×time − 1565 × heart rate.
()
Statistical Methods.Itwassoughttodetectabetween-group
dierence in the change of the SF-v score of points
(mental component summary) as it was considered clinically
important. Assuming that the standard deviation in this score
wouldbe,similartowhatwasobservedinasimilarsample
of patients [], a total sample size of would provide
% power to detect a dierence of points as statistically
signicant. e normality of the distribution of scores was
conrmed with the Kolmogorov-Smirnov test. e paired 𝑡-
test was later used to estimate the dierence in each outcome.
e signicance level was set at 𝑃 < 0.05.Allanalyseswere
carried out by using the statistical package SPSS (Chicago,
IL, USA).
3. Results
e mean and standard deviation of patients’ age was 43.10±
9.70. All subjects were nonsmokers and had a sedentary
lifestyle. % of patients were females and in the reproductive
age group. e anthropometric, cardiorespirator y tness, and
metabolic prole data are listed in Ta b l e .
Aer the -week intervention, the participants that
performed of a medium-impact exercise program showed
35
30
25
20
15
10
5
0
Week 0 Week 12
Timeline
VO2max (mL·kg·min−1)
P < 0.001
F : Inuence of a medium-impact exercise program on car-
diorespiratory tness by submaximal VO2max.
improvements in HRQoL in most domains, particularly the
vitality domain by points (% CI to ), the social
functioning domain by points (% CI to ), the mental
health domain by points (% CI to ), and mental
component summary by points (% CI to ). One of
the four domains within the physical component summary
(general health domain) showed signicant eect of the
exercise intervention: points (% CI to ), Table .
e paired 𝑡-test analysis revealed that the participants
had a greater cardiorespiratory tness at the end of the
intervention, measured by Rockport walk test (𝑃 = 0.01)and
by the submaximal VO2max (%; 𝑃 < 0.001), Figure .
Finally, the subjects participated . out of (SD .)
sessions over the weeks. No adverse events occurred during
oraertheexerciseinanyparticipant.
4. Discussion
e purpose of this study was to examine the inuence
of a medium-impact exercise program on HRQoL and
cardiorespiratory tness in females with sHT. To the authors’
knowledge, this is the rst systematic study evaluating the
potential eectiveness of exercise program in sHT on HRQoL
and VO2max. In our clinical experience, we consider that an
improvement of points on the SF-v resulting from this
intervention is clinically important. However, no threshold
has been established empirically for the amount of improve-
mentintheSF-vscorethatwomentypicallyfeelmakes
aerobic training worthwhile. Our estimation of the average
eect of the training had some uncertainty, with a % CI
ranging from to points. erefore, even if points is
a valid estimate for the smallest worthwhile eect, it must
be acknowledged that it is uncertain whether the statistically
signicant eect of exercise is clinically worthwhile.
e median mental component summary and general
health scores observed in the present study of women
weresimilartootherstudiesofpatientpopulationswith
conditions such as overweight [] or sedentary []. ere
areveryfewstudiesthatevaluatedHRQoLinsHT[,
], and none included cardiorespiratory tness and health
Journal of yroid Research
T : Inuence of a medium-impact exercise program on health-related quality of life (SF-v).
Timeline mean (SD) Dierence mean (SD) % CI
Week Week
Physical component summary ( to ) () () () −to
Physical function () () () −to
Role-physical () () () −to
Bodily pain () () () − to
General health () () () to
Mental component summary ( to ) () () () to
Vitality () () () to
Social functioning () () () to
Role-emotional () () () −to
Mental health () () () to
SF-v: Colombian standard version of the Medical Outcome Study Short-Form Health Survey.
statusinthesamestudy.Itisbelievedthatsomepsycho-
logical aspects of thyroid hypofunction, when present in
sHT, may be inuenced by physical ndings, as suggested
by the association between physical aspects of quality of
life, in the SF- evaluation and cardiorespiratory tness,
specially VO2max , in the present study. One of the primary
consequences of thyroid dysfunction is lower tolerance to
physical exertion, because of its implications involving the
muscle and cardiovascular systems. is interferes directly
with the patient’s ability to perform daily activities, thereby
reducing his quality of life. e study performed by Kahaly
et al. [] showed that subjects with thyroid dysfunction
have reduced workload tolerance at the anaerobic threshold,
compared to euthyroid subjects. According to these authors,
in hyperthyroidism this exercise intolerance is caused by
mitochondria oxidative dysfunction and in hypothyroidism,
by inadequate cardiovascular support.
Following the -week exercise program, trends to im-
provement were seen in most domains of the HRQoL
questionnaire, with statistically signicant changes in the
mental component summary and several of its domains. e
condence intervals were not narrow enough to conrm that
the benets would be worth the eort of exercising for these
women. Nevertheless, given the other benets of exercise in
females with sHT, physicians can prescribe exercise expecting
that it will improve quality of life. e recommended levels
of physical activity were positively associated with one or
more domains of health-related quality of life [,].
In particular, physical functioning, general health, vitality,
social functioning, and mental health are critically aected
by the recommended level of physical activity []. In the
current study, the physical aspects of HRQoL, such as mental
component summary and general health, seemed to be more
closely associated with the amount of physical activity than
the physical aspects are. is nding is consistent with several
previous studies [,].
e intervention showed better cardiorespiratory tness
results similar to those previously reported in healthy women
with high levels of physical activity [,,]. Interestingly,
it was observed that the VO2max diminishes progressively
during thyroid hormone deciency. So one might speculate
that the increase of VO2max observed in the training group
could have a benecial eect in patients with thyroid disease
occuring as a result of metabolic status.
e main limitation of this study is its uncontrolled
design. is study, however, was conceived as preliminary
research aiming to evaluate the potential usefulness of exer-
cise in patients with sHT. Nevertheless, the nding that sHT
mental symptoms were those showing greater improvement
is a fact that argues against a possible placebo eect despite
the lack of a control group. Investigation of other intervention
components, such as behavior therapy, is also needed. In
addition,futurerandomizedcontrolledtrialsshouldstudy
theeectsofexerciseinpatientswithdisorderssecondaryto
thyroid function variations and their implication, as well as
therapeutic options for this highly prevalent disease.
In summary, a supervised -week program of primarily
medium-impact exercise in females with sHT improves
health-related quality of life. Moreover, this exercise program
provedtohaveapositiveinuenceonthefunctionalcapacity
of the subjects, being eective in improving cardiorespiratory
tness.
Conflict of Interests
e authors declare that there is no conict of interests re-
garding the publication of this paper.
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