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ORIGINAL RESEARCH
Effectiveness of High-Intensity Interval Training vs
Moderate-Intensity Continuous Training in Patients
With Fibromyalgia: A Pilot Randomized Controlled
Trial
Tu
gba Atan, MD,
a
Yusuf Karavelio
glu, MD
b
From the
a
Department of Physical Medicine and Rehabilitation, Gaziler Physical Therapy and Rehabilitation Education and Research Hospital,
Ankara; and
b
Department of Cardiology, Faculty of Medicine, Hitit University, Corum, Turkey.
Abstract
Objective: To compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) combined with
strengthening and stretching exercises in patients with fibromyalgia.
Design: Interventional, single-blind, randomized controlled trial.
Setting: Outpatient rehabilitation center.
Participants: Women with fibromyalgia (NZ60) were randomized to HIIT, MICT, and control groups.
Interventions: HIIT included a 5-minute warm-up at 50% of peak heart rate and 4 cycles of 4 minutes at 80%-95% of peak heart rate followed by
3-minute recovery intervals at 70% of peak heart rate. MICT consisted of 45 minutes at 65%-70% of peak heart rate. Each aerobic training session
was followed by standardized strengthening and stretching exercises. The programs performed using cycle ergometers for 5 sessions per week for
6 weeks. The control group did not participate in any supervised exercise sessions.
Main Outcome Measures: The primary outcome measure was the Fibromyalgia Impact Questionnaire (FIQ). The secondary outcome measures
were visual analog scale for pain, Short Form-36 Health Survey (SF-36), cardiopulmonary exercise test (CPET), and body composition
parameters.
Results: Fifty-five participants completed the study. There was no significant difference in FIQ between HIIT vs MICT (1.03; 95% CI, 9.67 to
11.75) after treatment. Group-time interactions were significant for the FIQ between interventions and control (HIIT vs control, 16.20; 95% CI,
27.23 to 5.13 and MICT vs control, 17.24; 95% CI, 28.27 to 6.22) (all P<.001). There were significant group-time interactions for the
pain, SF-36, and CPET parameters between treatments and control (all P<.05). Body weight, fat percentage, fat mass, and body mass index
improved significantly (all P<.05) only in the MICT group after treatment.
Conclusions: The HIIT plus strengthening and stretching exercises and MICT plus strengthening and stretching exercises interventions showed
significant improvements for the effect of fibromyalgia, pain degree, functional capacity, and quality of life compared with the control group. HIIT
was not superior to MICT. Furthermore, body composition parameters were improved significantly only for the MICT group.
Archives of Physical Medicine and Rehabilitation 2020;101:1865-76
ª2020 by the American Congress of Rehabilitation Medicine
Fibromyalgia is a common rheumatic disease characterized by
widespread musculoskeletal pain, tenderness, fatigue, sleep
disorders, and cognitive and somatic complaints.
1
The diagnosis is
usually complicated because there is no objective examination
finding other than tenderness on palpation and there are no
specific laboratory or imaging findings.
2
Fibromyalgia is
widespread worldwide, its prevalence is reported to be 2%-4% of
the general population, and it is more common in women.
3
Recently, the European League Against Rheumatism presented
evidence-based recommendations for the management of fibro-
myalgia. Accordingly, prompt diagnosis and patient education is
required for optimal management. A graduated approach with the
aim of improving health-related quality of life should be followed.
Clinical Trial Registration No.: NCT03924960
Disclosures: none.
0003-9993/20/$36 - see front matter ª2020 by the American Congress of Rehabilitation Medicine
https://doi.org/10.1016/j.apmr.2020.05.022
Archives of Physical Medicine and Rehabilitation
journal homepage: www.archives-pmr.org
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Pharmacotherapy is only recommended for severe pain and sleep
disturbances. It should focus first on nonpharmacologic modal-
ities, and the only “strong for” evidence-based recommendation
was the use of aerobic and strengthening exercise.
2
Reviews of trials evaluating the effects of aerobic exercise in
patients with fibromyalgia have indicated that aerobic exercise
reduces pain, fatigue, or depressed mood and simultaneously
improves quality of life and physical fitness.
4,5
Aerobic exercise
with moderate intensity (60%-70% of age-adjusted predicted peak
heart rate) with a frequency of 2 or 3 times per week for at least 4-
6 weeks for a reduction of symptoms is recommended in the
management of fibromyalgia.
6,7
In recent years, high-intensity interval training (HIIT) has
become a popular alternative aerobic exercise method instead of
moderate-intensity continuous training (MICT) in cardiac reha-
bilitation units. It is superior to MICT in improving cardiovas-
cular fitness because it increases peak oxygen consumption
(VO
2
peak).
8
HIIT involves short burst of exercise at very high
intensity (80%-95% of peak heart rate) with recovery periods,
which relieves fatigue and maintains cardiovascular safety.
9
While the MICT lasts 30-60 minutes, HIIT contains 4-6 cycles
of 1-4 minutes with a maximum effort and lasts approximately
20-40 minutes in total. Therefore, another advantage of HIIT is
the need for a shorter time to achieve similar or greater effects
compared with MICT.
10
Our hypothesis is that 6 weeks of 5 weekly sessions of HIIT
will be superior in reducing the effect of fibromyalgia and
improving pain, functional capacity, and quality of life compared
with MICT. To our knowledge, there is no study investigating the
effect of HIIT in patients with fibromyalgia. Therefore, the aim of
this study is to assess the effects of HIIT vs MICT on pain,
functional capacity, and quality of life in women with
fibromyalgia.
Methods
Study design
The study was designed as a single-center, prospective, single-
blind, randomized controlled trial. The study protocol was
approved by the Institutional Human Research Ethics Committee
(approval no.: 19-KAEK-023). All the procedures were
conducted according to the Declaration of Helsinki. This study
was also registered in the Clinicaltrials.gov database
(NCT03924960). The reporting was conducted in accordance
with the Consolidated Standards of Reporting Trials and recom-
mendations for randomized trials. Participants were fully
informed about the experimental procedures and gave their
informed consent.
Participants and Assessments
The patients were recruited from the physical medicine and
rehabilitation outpatient clinic. Patients who were willing to
participate in the study were assessed to evaluate their eligibility
for the study and to provide detailed information about the study.
The inclusion criteria were as follows: (1) 18 years or older; (2)
female sex; (3) diagnosis according to the American College of
Rheumatology 2016 diagnostic criteria for fibromyalgia. These
criteria include a history of generalized pain in at least 4 of 5
regions at a similar level for at least 3 months, widespread pain
index 7 and symptom severity scale score 5, or widespread
pain index of 4-6 and symptom severity scale score 9; a diag-
nosis of fibromyalgia is valid irrespective of other diagnoses; (4)
no participation in a designed sports or exercise training programs
in the previous 3 months; (5) stable medical treatment for
symptoms for at least 4 weeks prior to participation; and (6) no
pregnancy/breastfeeding. Patients were excluded if they had co-
morbid inflammatory rheumatic and/or connective tissue diseases
or cardiovascular and/or musculoskeletal problems that could
prevent participation in an exercise program. During the study, the
recommended pharmacologic treatments with evidence level
1A (amitriptyline, duloxetine/milnacipran, pregabalin, cyclo-
benzaprine)
2
were continued without changing the dose. Among
our patients, only duloxetine and pregabalin use were available.
Apart from this, patients were not allowed to use any other
analgesic drugs (paracetamol, nonsteroidal anti-inflammatory
drugs, opioids) for pain, because it may affect the outcome
measurements. The study began March 2019 and ended
February 2020.
A total of 117 patients who were followed up in our outpatient
clinic with a diagnosis of fibromyalgia were screened, and 60 of
them enrolled in the study. The Consolidated Standards of
Reporting Trials diagram for participants is shown in fig 1.
Baseline demographic and clinical characteristics (duration of
disease, medical treatments, level of physical activity according to
the International Physical Activity Questionnaire
11
) of the
patients who met the initial screening criteria were recorded. In
addition, outcome measures of body composition, pain, and
psychological variables were analyzed.
All participants underwent a symptom-limited maximal
cardiopulmonary exercise test (CPET) at baseline and followed by
6-week exercise intervention of HIIT or MICT. The pre- and
posttest procedure was identical. The test was performed on a
computer-controlled cycle ergometer
a
with using an incremental
protocol. Twelve-lead electrocardiogram
b
and gas exchange vari-
ables
c
were recorded continuously throughout the test. CPET
variables were analyzed by a cardiology specialist.
After the baseline exercise test, participants were randomly
assigned to 3 groups (HIIT: HIIT plus strengthening and stretching
exercises group, MICT: MICT plus strengthening and stretching
exercises group, control: usual care group) using a computer-
generated program including a randomized table of numbers
formed by an independent individual not involved with any other
aspect of the trial. Numbered cards with a random assignment
containing information about the group allocation in an opaque,
sealed envelopes were prepared by the independent individual.
Physiotherapists opened the envelope and applied the planned
treatment program according to the group.
Outcome measurements were repeated within 3 days of
completing the exercise interventions by the same investigators
blinded to the randomization.
List of abbreviations:
BMI body mass index
CPET cardiopulmonary exercise test
FIQ Fibromyalgia Impact Questionnaire
HIIT high-intensity interval training
MICT moderate-intensity continuous training
SF-36 Short Form-36 Health Survey
VAS visual analog scale
VO
2
peak peak oxygen consumption
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Interventions
All exercise sessions were supervised by experienced cardiac
rehabilitation nurses and physiotherapists during HIIT and MICT.
The participants were taught how to exercise in a moderate- or
high-intensity training session with a trial session. Training in-
tensity was based on the peak heart rate, which was recorded
during the baseline CPET.
The HIIT program was performed using cycle ergometers 5
sessions per week for the 6-week intervention (30 sessions). Each
session consisted of a 5-minute warm-up period cycling at 50% of
peak heart rate followed by 4 sets of 4-minute high-intensity in-
tervals at 80%-95% of peak heart rate interspersed with 3 sets of
3-minute of active recovery intervals at 70% of peak heart rate and
5-minute cool down period cycling at 50% of peak heart rate.
Total exercise time was 35 minutes.
The MICT program performed using cycle ergometers 5 ses-
sions per week for the 6-week intervention. Each session consisted
of a 5-minute warm-up period cycling at 50% of peak heart rate
followed by continuously activity at an intensity of 65%-70% of
peak heart rate and 5-minute cool down period cycling at 50% of
peak heart rate. Total exercise time was 55 minutes.
Each aerobic training session was followed by 15 minutes of
standardized strengthening and stretching exercise training for
both intervention groups. Strengthening exercises were performed
for 10 minutes, where major muscle groups were strengthened
through shoulder press, dumbbell press, shoulder elevation with
resistance, biceps curl, squats, hip flexion and extension, and
standing hip exercises using 1-3 kg of weight loads and 1 set of 8-
10 repetitions. Finally, stretching exercises were performed for 5
minutes by holding the main muscle-tendon groups for 20-30
seconds, with 4-5 repetitions for each muscle group. Percentage of
sessions were also recorded to determine adherence with the
training program.
The control group did not participate in any supervised exer-
cise sessions, but they had specific recommendations regarding
exercise for fibromyalgia. They were only contacted once by
telephone to schedule an appointment for the posttest.
Primary outcome measure of the study
Fibromyalgia Impact Questionnaire
The Fibromyalgia Impact Questionnaire (FIQ) was designed to
measure the health status of patients with fibromyalgia. It is a self-
administered test that measures 10 different items related to
physical function, well-being, loss of working day, pain, fatigue,
stiffness, anxiety, and depression. Total score range from 0-100,
with higher scores indicating higher levels of symptoms and
severity.
12
Fig 1 Flow diagram of the study. Abbreviation: CONSORT, Consolidated Standards of Reporting Trials.
Interval training for fibromyalgia 1867
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Secondary outcomes
Visual analog scale for pain
Pain intensity was measured with visual analog scale (VAS),
which is used to measure musculoskeletal pain with very good
reliability and validity (VAS, 0-10cm; 0Zno pain, 10Zse-
vere pain).
13
Short Form-36 Health Survey 36
Short Form-36 Health Survey (SF-36) contains 36 items that are
used to evaluate the quality of life of patients with chronic pain. It
measures 8 different domains that address physical functioning,
physical role limitation, pain, general health, vitality, social
functioning, emotional role limitation, and mental health. The
score of each domain ranges from 0 (worst quality of life) to 100
(best quality of life).
14
Cardiorespiratory fitness
CPET is a method that comprehensively evaluates the exercise
response to the cardiac, pulmonary, musculoskeletal, and
hematologic systems and allows for more precise, objective, and
detailed examination of cardiopulmonary functional capacity.
Oxygen consumption, heart rate, blood pressure, workload,
duration of test, and maximal metabolic equivalent were assessed
at peak cardiovascular response and ventilatory threshold.
During the termination of the test, the respiratory exchange ratio
was intended to reach 1.1, and values above 1.05 were also
accepted.
15
Body composition parameters
All patients were evaluated with a body composition analyzer.
d
Body weight, muscle, and fat measurements were recorded.
Height measurements (without shoes) were taken with a
stadiometer.
Sample size
The sample size estimation was performed using the G*Power
software (version 3.1).
e
It was determined that 17 individuals for
each group must be recruited to detect a difference at 5% type 1
error level with 80% power for an effect size of 0.733 based on the
FIQ scores reported in a previous research.
16
However, including
w20% for possible future losses, 20 individuals were allocated
into the 3 groups.
Statistical analysis
Demographic data and clinical features were reported as mean and
standard deviation. Categorical variable was presented as number
and percent. Visual assessment and Shapiro-Wilk test were used
for normality evaluation. The assumption of normality was
confirmed, and parametric tests were performed. Outcome
measurements were analyzed using a mixed factorial analysis of
variance with repeated measures (3 groups: HIIT vs MICT vs
control2-times: pre- and post intervention). Post hoc compari-
sons were done with Bonferroni test. The effect size was
calculated by the partial eta squared (hp
2
) value. Effect size values
were interpreted as follows: >0.2, large effect size; >0.1, medium
effect size; and >0.05, small effect size. One-way analysis of
variance was conducted to identify the differences between
groups. Data analyses were performed using IBM SPSS Statistics
for Windows version 21.0,
f
and P.05 was considered a statisti-
cally significant difference.
Results
During the 6-week intervention program no adverse events were
reported. Five participants were unable to complete the training
program or outcome measurements post intervention: 1 from
HIIT, 1 from MICT, and 3 from control group. Their data were
excluded from the analyses, and 55 participants completed the
study (see fig 1). Adherence to training was 98.6%2.4% for HIIT
and 95.5%3.8% for MICT intervention (PZ.085).
Demographic and clinical variables did not show any signifi-
cant difference between the 3 study groups (table 1).
There was no significant difference in FIQ as our primary
outcome measurement between HIIT vs MICT (1.03; 95% CI,
9.67 to 11.75) after treatment. Group-time interactions were
significant for the FIQ between interventions and control (HIIT vs
control, 16.20; 95% CI, 27.23 to 5.13 and MICT vs control,
17.24; 95% CI, 28.27 to 6.22) (all P<.001) (fig 2). Effect
sizes were large regarding treatments (hp
2
Z0.262), time
(hp
2
Z0.641), and interaction (hp
2
Z0.480).
Similarly, VAS-pain and SF-36 subgroups showed significant
improvements for the intervention groups (table 2). The CPET
parameters of duration of test, peak power, VO
2
peak, and maximal
metabolic equivalent showed significant group-time interactions
between treatments (all P<.05). The difference between treat-
ments was originating from the HIIT vs control and MICT vs
control (table 3). Body composition parameters of body weight,
fat mass, and body mass index (BMI) did not differ between
treatments but changed over time (all P<.05). There were not
significant changes regarding the interaction between groups,
except for fat percentage. Body weight, fat percentage, fat mass,
and BMI improved significantly (all P<.05) only in the MICT
group after the 6-week intervention (table 4).
Discussion
The main findings from this study reinforce the recommendations
that patients with fibromyalgia should perform structured aerobic
exercises at a high or moderate intensity combined with
strengthening and stretching exercises to improve symptoms of
disease. In both the HIIT plus strengthening and stretching exer-
cises and MICT plus strengthening and stretching exercises
groups, effect of the fibromyalgia measured by the FIQ, which is
the primary outcome measure, showed significant improvement
after the interventions compared with the control group. Similarly,
HIIT plus strengthening and stretching exercises and MICT plus
strengthening and stretching exercises provided comparable im-
provements in pain, quality of life, and functional capacity. In the
literature, various exercises with positive results were used to treat
symptoms of fibromyalgia. It was emphasized that aerobic
exercise and strength training are the most effective treatment for
fibromyalgia symptoms and improve cardiorespiratory fitness.
17,18
Therefore, in this study, we wanted to compare some outcome
measures of fibromyalgia after performing different aerobic ex-
ercise protocols (HIIT or MICT) combined with strengthening and
stretching exercises with a control group. In a study by Dobkin
et al the maintenance of an exercise program in women with
fibromyalgia appeared to be contingent on being able to deal with
stress, pain, barriers to exercise, and disability.
19
HIIT and MICT
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are 2 types of aerobic exercises that have become increasingly
popular in physical activity interventions.
20
HIIT has been pro-
posed as a time-efficient form of exercise that may overcome
motivational barriers associated with traditional MICT exercise.
10
In a review by Ito et al, although MICT is the main training
regimen recommended in the guidelines for cardiac rehabilitation,
HIIT was more effective than MICT regarding short-term effects
in terms of central and peripheral adaptations.
21
In another review,
HIIT provided greater improvements in VO
2
peak than MICT for
patients at high risk of cardiovascular disease.
22
In this study,
contrary the hypothesis and the literature, no significant difference
was observed in disability, pain, quality of life, and functional
capacity between the 2 intervention groups. However, significant
improvements were noted in both groups. Similar to our findings,
there are some studies in the literature that report that HIIT is not
superior to MICT.
23,24
Previous studies have shown that the prevalence of being
overweight is high in patients with fibromyalgia, and that may
been associated with level of pain, symptom severity, disease
activity, fatigue, anxiety, or quality of life. In this study, in
accordance with the literature, baseline BMI values of patients are
high in all 3 groups. Physical exercise also helps maintain healthy
body composition values, which is an important factor in their
relationship to disease symptoms that cause dependence in women
with fibromyalgia.
25
One of the interesting findings of this study
was that the body composition parameters showed a significant
reduction only for the MICT group. In a systematic review and
meta-analysis, HIIT and MICT showed similar efficacy in all body
composition measurements, but HIIT may be a time-efficient
component of weight management programs.
26
The results for
the body composition parameters are not in accordance with
previous findings from independent intervention studies
27,28
and
systematic reviews
26,29
that state HIIT can be considered as an
effective strategy to improve body weight, fat percentage, and
BMI. The differences between these results and ours may be
explained by sources of variability between individuals, including
behavioral or environmental changes and nutritional status.
Aerobic exercise and strength training have been well tolerated
by the patients, with a small number of adverse events.
7,30,31
Additionally, the mean adherence of patients to the intervention
in the included studies was 84%. They reported this as a positive
result, considering that the most of this population had a low level
of physical activity.
32,33
When the characteristics of the patients
were examined in this study, physical activity levels in all groups
were similarly low. In accordance with the literature, no adverse
events were observed in our study, and adherence to both aerobic
and strength training protocols was found to be very high in the
intervention groups.
Study limitations
A limitation of the present study was although adherence to both
supervised exercise programs was very high, feasibility was not
studied. Treatments were compared only within the scope of the
Table 1 Patient characteristics of the study groups
Variables HIIT (nZ19) MICT (nZ19) Control (nZ17) PValue
Age (y), mean SD 46.579.41 47.368.01 52.708.96 .090
Height (cm), mean SD 156.715.39 156.424.41 157.175.60 .907
Initial weight (kg), mean SD 76.3312.09 75.8310.78 79.397.65 .552
Education level
Low, n (%) 15 (78.9) 13 (68.4) 13 (76.5) .545
Intermediate, n (%) 2 (10.5) 3 (15.8) 2 (11.8)
High, n (%) 2 (10.5) 3 (15.8) 2 (11.8)
Duration of disease (mo), mean SD 37.5721.52 24.0014.96 27.8217.66 .071
Medication
Duloxetine, n (%) 3 (15.8) 5 (26.3) 5 (29.4) .595
Pregabalin, n (%) 5 (26.3) 7 (36.8) 10 (58.8) .131
Tobacco
Former, n (%) 2 (10.5) 3 (15.8) 2 (11.8) .056
No, n (%) 16 (84.2) 14 (73.7) 15 (88.2)
Yes, n (%) 1 (5.3) 2 (10.5) 0 (0.0)
IPAQ, total score (MET/min), mean SD 581.52346.29 663.76359.09 441.58404.32 .165
NOTE. Control, usual care group; HIIT, high-intensity interval training plus strengthening and stretching exercises group; MICT, moderate-intensity
continuous training plus strengthening and stretching exercises group.
Abbreviation: IPAQ, International Physical Activity Questionnaire.
Fig 2 Difference between treatments for the Fibromyalgia Impact
Questionnaire.
Interval training for fibromyalgia 1869
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Table 2 Within- and between-group changes (group, time, and interaction effects) for Fibromyalgia Impact Questionnaire, VAS for pain, and SF-36 data
Outcome
Measurements HIIT MICT Control
Mean Difference (95% CI)
PValue*
Group
PValue
hp
2
Time
PValue
hp
2
GroupTime
PValue
hp
2
HIIT vs MICT HIIT vs Control MICT vs Control
FIQ 1.03 (9.67 to
11.75)
16.20 (27.23
to 5.13)
y
17.24 (28.27
to 6.22)
y
Preintervention 66.1911.73 62.9814.75 66.9811.95 .613 <.001
x
<.001
x
<.001
x
Post intervention 35.8017.35 36.9319.63 67.4413.20 .262 .641 .480
Pvalue
z
<.001
z
<.001
z
.725
VAS for pain 0.13 (1.40 to
1.14)
2.08 (3.39 to
0.77)
y
1.95 (3.26 to
0.64)
y
Preintervention 7.781.81 7.891.76 8.291.61 .662 <.001
x
<.001
x
<.001
x
Post intervention 4.211.93 4.362.43 7.881.36 .260 .670 .406
Pvalue
z
<.001
z
<.001
z
.248
SF-36 Physical
functioning
5.42 (17.83 to
6.99)
19.53 (7.07-
31.99)
y
24.95 (12.18-
37.73)
y
Preintervention 44.4723.20 56.1020.88 42.3515.82 .097 <.001
x
<.001
x
<.001
z
Post intervention 78.4218.48 77.6314.46 41.4717.38 .329 .443 .327
Pvalue
z
<.001
z
<.001
z
.764
SF-36 Role
limitations
because of
physical health
8.55 (28.50 to
11.39)
16.17 (4.35 to
36.70)
24.72 (4.19-
45.25)
y
Preintervention 13.1519.30 26.3133.82 16.1721.54 .270 .015
x
<.001
x
.003
z
Post intervention 61.8430.46 65.7835.56 26.4733.62 .149 .513 .202
Pvalue
z
<.001
z
<.001
z
.150
SF-36 Role
limitations
because of
emotional
problems
9.06 (31.17 to
13.04)
26.48 (3.73-
49.23)*
35.55 (12.80-
58.30)
y
Preintervention 22.2035.05 38.6038.91 21.5737.16 .273 .001
x
<.001
x
.001
z
Post intervention 71.9429.94 73.6830.59 19.6031.31 .234 .357 .251
Pvalue
z
<.001
z
.001
z
.668
SF-36 Energy/
fatigue
3.42 (9.12 to
15.96)
21.30 (8.40-
34.21)
y
17.88 (4.98-
30.79)
y
Preintervention 27.6318.88 29.2121.09 25.2915.04 .820 <.001
x
<.001
x
<.001
z
Post intervention 62.6317.97 54.2120.70 22.3517.51 .267 .472 .382
Pvalue
z
<.001
z
<.001
z
.236
SF-36 Emotional
well-being
5.07 (6.71 to
16.87)
13.82 (1.68-
25.96)*
8.74 (3.39 to
20.88)
Preintervention 43.1520.24 40.6316.12 45.1718.64 .760 .024
x
<.001
x
<.001
z
Post intervention 71.7817.45 64.1517.63 42.1119.85 .134 .369 .289
(continued on next page)
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Table 2 (continued )
Outcome
Measurements HIIT MICT Control
Mean Difference (95% CI)
PValue*
Group
PValue
hp
2
Time
PValue
hp
2
GroupTime
PValue
hp
2
HIIT vs MICT HIIT vs Control MICT vs Control
Pvalue
z
.001
z
.047
z
.232
SF-36 Social
functioning
5.59 (9.63 to
20.81)
14.86 (0.80 to
30.52)
9.26 (6.39 to
24.93)
Preintervention 51.9723.29 50.0022.43 51.4720.19 .960 .071 <.001
x
<.001
z
Post intervention 82.8919.18 73.6822.00 53.6721.99 .097 .472 .264
Pvalue
z
<.001
x
<.001
x
.593
SF-36 Pain 5.65 (18.68 to
7.37)
12.65 (0.75 to
26.06)
18.30 (4.89-
31.71)
y
Preintervention 18.2817.58 29.8616.63 29.2620.64 .103 .005
x
<.001
x
<.001
z
Post intervention 62.8925.63 62.6317.60 26.6115.90 .185 .599 .484
Pvalue
z
<.001
x
<.001
x
.471
SF-36 General health 0.92 (12.57 to
14.41)
17.29 (3.40-
31.18)
y
16.37 (2.48-
30.25)
y
Preintervention 32.6319.17 37.3616.19 30.2916.43 .461 .005
x
<.001
z
.001
x
Post intervention 63.4222.30 56.8424.61 31.1715.86 .185 .440 .286
Pvalue
z
<.001
x
.002
x
.779
SF-36 Health change 4.73 (20.17 to
10.70)
17.43 (34.36 to
0.51)
y
22.17 (6.59-
37.75)
Preintervention 31.5728.67 32.8925.07 27.0523.38 .783 .003
x
<.001
x
.007
x
Post intervention 69.4722.90 77.6320.23 39.1126.99 .200 .524 .174
Pvalue
z
<.001
x
<.001
x
.096
NOTE. Control, usual care group; HIIT, high-intensity interval training plus strengthening and stretching exercises group; MICT, moderate-intensity continuous training plus strengthening and stretching
exercises group. Data expressed as mean SD; hp
2
Zpartial eta squared effect size.
*Pvalue for basal measurements among the 3 groups.
y
Significant differences between groups (P<.05).
z
Pvalue for pre- and postintervention measurements for each group.
x
Significant Pvalues (P<.05).
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Table 3 Within- and between- group changes (group, time, and interaction effects) for CPET parameters
Outcome
Measurements HIIT MICT Control
Mean Difference
(95% CI) P
Value*
Group
PValue
hp
2
Time
PValue
hp
2
GroupTime
PValue
hp
2
HIIT vs MICT HIIT vs Control MICT vs Control
Duration of test
(s)
0.008 (1.35 to 1.36) 2.76 (1.36-4.16)
y
2.75 (1.31-4.18)
y
Preintervention 16.621.82 16.681.80 15.621.79 .162 <.001
x
<.001
x
<.001
x
Post intervention 20.472.16 20.392.10 15.951.98 .362 .695 .458
Pvalue
z
.010
z
<.001
z
.140
Peak power (W) 0.92 (10.06 to 8.22) 17.74 (8.33-27.15)
y
18.66 (9.25-
28.07)
y
Preintervention 92.3611.67 92.9412.19 85.7612.49 0.158 <.001
x
<.001
x
<.001
x
Post intervention 116.9412.51 118.2113.50 88.0513.47 .366 .725 .489
Pvalue
z
<.001
z
<.001
z
.212
Resting HR
(bpm)
1.65 (5.95 to 9.27) 7.39 (0.24 to
1.90)
5.73 (2.09 to
13.56)
Preintervention 92.5213.50 87.8913.16 88.057.84 .210 .061 .309 .221
Post intervention 83.7810.35 85.1011.07 83.4714.65 .102 .020 .139
Pvalue
z
.024
z
.018
z
.068
Resting SBP
(mmHg)
1.18 (11.19 to 13.56) 0.59 (13.33 to
12.13)
1.78 (14.52 to
10.95)
Preintervention 124.7832.12 123.7820.96 120.7611.69 .869 .939 .168 .308
Post intervention 117.8912.03 116.5212.82 123.1110.50 .002 .03 .044
Pvalue
z
.049
z
.018
z
.056
Resting DBP
(mmHg)
2.10 (4.39 to 8.60) 5.06 (1.61 to
11.75)
2.96 (3.72 to
9.64)
Preintervention 85.637.63 82.3610.56 79.7613.85 .275 .181 .061 .834
Post intervention 81.218.96 80.268.75 76.9410.15 .064 .066 .007
Pvalue
z
.970 .069 .502
Peak HR (bpm) 1.26 (10.61 to 13.14) 9.85 (2.3 to
22.07)
8.59 83.63 to
20.81)
Preintervention 163.3118.82 161.2114.45 159.4119.18 .137 .109 .906 .265
Post intervention 159.1514.16 158.7313.09 159.3518.38 .082 .001 .050
Pvalue
z
<.001
z
.012
z
.449
Peak SBP
(mmHg)
7.92 (10.68 to 26.52) 5.34 (24.48 to
13.79)
13.26 (32.40 to
5.87)
Preintervention 197.7822.66 186.4726.62 195.2934.79 .223 .232 .219 .064
Post intervention 187.0532.63 182.5226.61 182.2329.74 .055 .068 .100
Pvalue
z
.438 .083 .300
Peak DBP
(mmHg)
23.52 (28.26 to 75.32) 22.56 (30.72 to
75.86)
0.95 (54.25 to
52.33)
Preintervention 97.7312.58 95.7316.23 97.3523.29 .935 .457 .625 .467
(continued on next page)
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Table 3 (continued )
Outcome
Measurements HIIT MICT Control
Mean Difference
(95% CI) P
Value*
Group
PValue
hp
2
Time
PValue
hp
2
GroupTime
PValue
hp
2
HIIT vs MICT HIIT vs Control MICT vs Control
Post intervention 92.1011.92 90.0515.66 90.3527.54 .030 .005 .029
Pvalue
z
.520 .112 .502
VO
2
peak (mL/
min)
0.01 (0.14 to 0.12) 0.20 (0.06-0.34)
y
0.21 (0.07-0.35)
y
Preintervention 1.450.23 1.470.18 1.390.17 .066 <.001
x
<.001
x
.016
x
Post intervention 1.690.18 1.690.19 1.430.14 .257 .735 .147
Pvalue
z
<.001
z
<.001
z
.059
VO
2
peak (mL/kg/
min)
0.44 (2.13 to 1.24) 3.42 (1.68-5.16)
y
3.86 (2.12-5.60)
y
Preintervention 19.151.83 19.422.24 18.947.18 .067 <.001
x
<.001
x
.001
x
Post intervention 22.682.51 23.312.94 18.105.52 .406 .651 .252
Pvalue
z
<.001
z
.007
z
.062
Maximal MET 0.10 (0.66 to 0.45) 0.94 (0.66 to
0.45)
y
1.04 (0.47-1.62)
y
Preintervention 5.190.52 5.260.81 4.800.69 .100 <.001
x
<.001
x
.001
x
Post intervention 6.370.79 6.510.89 4.880.77 .316 .694 .471
Pvalue
z
<.001
z
<.001
z
.130
Peak RER 0.004 (0.04 to 0.03) 0.0009 (0.04 to
0.03)
0.003 (0.03 to
0.04)
Preintervention 1.080.06 1.090.04 1.080.06 .907 .960 .518 .917
Post intervention 1.070.05 1.080.06 1.070.04 .002 .007 .003
Pvalue
z
.302 .279 .137
NOTE. Control, usual care group; HIIT, high-intensity interval training plus strengthening and stretching ex
ercises group; MICT, moderate-intensity continuous training plus strengthening and stretching exercises group. Data expressed as mean SD; hp
2
Zpartial eta squared effect size.
Abbreviations: DBP, diastolic blood pressure; HR, heart rate; MET, metabolic equivalent; RER, respiratory exchange ratio; SBP, systolic blood pressure.
*Pvalue for basal measurements among the 3 groups.
y
Significant differences between groups (P<.05).
z
Pvalue for pre- and postintervention measurements for each group.
x
Significant Pvalues (P<.05).
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Table 4 Within- and between-group changes (group, time, and interaction effects) for body composition parameters
Outcome
Measurements HIIT MICT Control
Mean Difference (95% CI)
P
Value*
Group
PValue
hp
2
Time
PValue
hp
2
GroupTime
PValue
hp
2
HIIT vs MICT HIIT vs Control MICT vs Control
Body weight (kg) 1.04 (6.99 to 9.07) 3.28 (11.55 to 4.98) 4.32 (12.59 to 3.94)
Preintervention 76.0811.88 75.7410.58 79.397.65 .535 .413 .048
z
.366
Post intervention 75.882.16 74.2410.12 79.248.06 .033 .073 .038
Pvalue
y
.242 .006
z
.875
Fat (%) 0.22 (3.02 to 3.46) 1.40 (4.74 to 1.93) 1.62 (4.96 to 1.71)
Preintervention 37.914.53 38.084.96 39.082.87 .679 .437 .220 .008
z
Post intervention 37.214.42 36.604.71 38.852.76 .031 .057 .129
Pvalue
y
.254 .002
z
.634
Fat mass (kg) 0.49 (4.73 to 5.71) 2.22 (7.60 to 3.14) 2.72 (8.09 to 2.65)
Preintervention 29.437.74 29.277.44 31.357.48 .602 .422 <.001
z
.160
Post intervention 28.867.15 27.546.77 30.904.75 .033 .242 .068
Pvalue
y
.056 <.001
z
.399
Fat free mass (kg) 0.43 (2.99 to 3.85) 1.11 (4.64 to 2.40) 1.55 (5.07 to 1.97)
Preintervention 46.954.90 46.463.96 48.484.25 .372 .540 .568 .190
Post intervention 47.314.78 46.933.97 48.024.04 .023 .006 .062
Pvalue
y
.354 .252 .215
Muscle mass (kg) 0.41 (3.08 to 3.91) 0.08 (3.51 to 3.68) 0.33 (3.93 to 3.27)
Preintervention 44.584.66 44.103.78 44.675.02 .918 .953 .247 .657
Post intervention 44.914.54 44.563.77 44.654.78 .002 .026 .016
Pvalue
y
.367 .248 .953
BMI 0.40 (3.17 to 3.99) 1.55 (5.24 to 2.13) 1.96 (5.65 to 1.72)
Preintervention 31.135.53 30.984.55 32.693.03 .486 .109 .043
z
.378
Post intervention 30.965.11 30.194.45 32.613.61 .082 .076 .037
Pvalue
y
.299 .008
z
.819
NOTE. BMI calculated as weight in kilograms divided by height in meters squared; Control, usual care group; HIIT, high-intensity interval training plus strengthening and stretching exercises group; MICT,
moderate-intensity continuous training plus strengthening and stretching exercises group. Data expressed as mean SD; hp
2
Zpartial eta squared effect size.
*Pvalue for basal measurements among the 3 groups.
y
Pvalue for pre- and postintervention measurements for each group.
z
Significant Pvalues (P<.05).
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established outcome criteria. However, no data were collected on
whether the treatment program was enjoyable and whether its
duration was sufficient. Although the HIIT plus strengthening and
stretching exercises protocol does not seem to have outperformed
the MICT plus strengthening and stretching exercises protocol,
superiority can be demonstrated because of its completion in a
shorter period of time in future feasibility studies. In addition, the
most effective component of the exercise programs (HIIT, MICT,
strengthening, stretching) cannot be determined. Another limi-
tation of the study is that the follow-up period was short for un-
derstanding the maintenance of the long-term effects of
interventions in subjects with fibromyalgia. We also noticed the
potential imbalance in duration of disease and International
Physical Activity Questionnaire scores between groups, which
could confuse results. In addition, these results cannot be gener-
alized to other populations, such as men.
Conclusions
Thirty-sessions of HIIT or MICT plus strengthening and stretching
exercises were beneficial for disability, pain degree, functional
capacity, and quality of life in the treatment of fibromyalgia.
Contrary to our hypothesis, HIIT was not superior to MICT.
Moreover, body composition parameters showed significant
improvement only for the MICT group. Adherence to the training
sessions was similar when HIIT plus strengthening and stretching
exercises and MICT plus strengthening and stretching exercises
were performed in a supervised unit.
Suppliers
a. Ergoline Bicycle Ergometer Ergoselect 200; Ergoline.
b. Meta Control 3000; CORTEX Biophysik GmbH.
c. Metalyzer 3B-MICROMED; CORTEX Biophysik GmbH.
d. MC-980; Tanita, Tokyo, Japan.
e. G)Power software version 3.1; Heinrich Heine University
Du
¨sseldorf.
f. IBM SPSS Statistics for Windows version 21.0; IBM.
Keywords
Cardiorespiratory fitness; Exercise; High-intensity interval
training; Oxygen consumption; Rehabilitation
Corresponding author
Tu
gba Atan, MD, Department of Physical Medicine and
Rehabilitation, Gaziler Physical Therapy and Rehabilitation
Education and Research Hospital, Ankara, Turkey. E-mail
address: tubaatan@gmail.com.
Acknowledgments
We thank all the members of cardiac rehabilitation unit: nurses
Yasemin Yener, Sultan Yetik, Damla Beykoz, Fatma O
¨zkul;
physiotherapists Ays
‚e Akdal, Cengiz Ciga; and secretaries Nur
Mehtap Barut and Sema O
¨ncu
¨l.
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