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Effectiveness of high-intensity interval training on glycemic control and cardiorespiratory fitness in patients with type 2 diabetes: a systematic review and meta-analysis

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Aims: The aim of this systematic review and meta-analysis was to quantify the effect of high-intensity interval training (HIIT) on glycemic control and cardiorespiratory fitness compared with moderate-intensity training (MICT) and no training at all in patients with type 2 diabetes (T2D). Methods: Relevant articles were sourced from PubMed, Embase, the Web of Science, EBSCO, and the Cochrane Library. Randomized-controlled trials were included based upon the following criteria: participants were clinically diagnosed with T2D, outcomes that included glycemic control (e.g., hemoglobin A1c); body composition (e.g., body weight); cardiorespiratory fitness (e.g., VO2peak) are measured at baseline and post-intervention and compared with either a MICT or control group. Results: Thirteen trials involving 345 patients were finally identified. HIIT elicited a significant reduction in BMI, body fat, HbA1c, fasting insulin, and VO2peak in patients with type 2 diabetes. Regarding changes in the body composition of patients, HIIT showed a great improvement in body weight (mean difference: - 1.22 kg, 95% confidence interval [CI] - 2.23 to - 0.18, P = 0.02) and body mass index (mean difference: - 0.40 kg/m2, 95% CI - 0.78 to - 0.02, P = 0.04) than MICT did. Similar results were also found with respect to HbA1c (mean difference: - 0.37, 95% CI - 0.55 to - 0.19, P < 0.0001); relative VO2peak (mean difference: 3.37 ml/kg/min, 95% CI 1.88 to 4.87, P < 0.0001); absolute VO2peak (mean difference: 0.37 L/min, 95% CI 0.28 to 0.45, P < 0.00001). Conclusions: HIIT may induce more positive effects in cardiopulmonary fitness than MICT in T2D patients.
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Aging Clinical and Experimental Research (2019) 31:575–593
https://doi.org/10.1007/s40520-018-1012-z
REVIEW
Effectiveness ofhigh-intensity interval training onglycemic control
andcardiorespiratory fitness inpatients withtype 2 diabetes:
asystematic review andmeta-analysis
Jing‑xinLiu1· LinZhu1,2· Pei‑junLi1· NingLi1· Yan‑bingXu3
Received: 4 May 2018 / Accepted: 14 July 2018 / Published online: 30 July 2018
© The Author(s) 2018
Abstract
Aims The aim of this systematic review and meta-analysis was to quantify the effect of high-intensity interval training (HIIT)
on glycemic control and cardiorespiratory fitness compared with moderate-intensity training (MICT) and no training at all
in patients with type 2 diabetes (T2D).
Methods Relevant articles were sourced from PubMed, Embase, the Web of Science, EBSCO, and the Cochrane Library.
Randomized-controlled trials were included based upon the following criteria: participants were clinically diagnosed with
T2D, outcomes that included glycemic control (e.g., hemoglobin A1c); body composition (e.g., body weight); cardiorespira-
tory fitness (e.g., VO2peak) are measured at baseline and post-intervention and compared with either a MICT or control group.
Results Thirteen trials involving 345 patients were finally identified. HIIT elicited a significant reduction in BMI, body
fat, HbA1c, fasting insulin, and VO2peak in patients with type 2 diabetes. Regarding changes in the body composition of
patients, HIIT showed a great improvement in body weight (mean difference: −1.22kg, 95% confidence interval [CI] − 2.23
to − 0.18, P = 0.02) and body mass index (mean difference: −0.40kg/m2, 95% CI − 0.78 to − 0.02, P = 0.04) than MICT
did. Similar results were also found with respect to HbA1c (mean difference: −0.37, 95% CI − 0.55 to − 0.19, P < 0.0001);
relative VO2peak (mean difference: 3.37ml/kg/min, 95% CI 1.88 to 4.87, P < 0.0001); absolute VO2peak (mean difference:
0.37L/min, 95% CI 0.28 to 0.45, P < 0.00001).
Conclusions HIIT may induce more positive effects in cardiopulmonary fitness than MICT in T2D patients.
Keywords High-intensity interval training· Glycemic control· Cardiorespiratory fitness· Type 2 diabetes
Introduction
Type 2 diabetes (T2D) is a metabolic disease characterized
by hyperglycemia resulting from a resistance to insulin
or a relative insulin insufficiency that can induce cardio-
vascular disease and lead to cardiovascular deterioration.
According to epidemiological survey results, more than
422million people worldwide were living with diabetes
in 2014 [1], with a predicted prevalence of 552million by
2030 [2]. Because of the growing economic and social bur-
dens associated with T2D treatment, effective and accessi-
ble lifestyle interventions for people with T2D have never
been more important. Exercise intervention is recognized
as an integral concept for lifestyle intervention in T2D
patients [3, 4], and it has been recommended by both the
American Diabetes Association and the American College
of Sports Medicine that patients should perform at least
150min/week of moderate-to-vigorous aerobic exercise
[5, 6]. Abundant evidence from randomized-controlled
trials (RCTs) shows the benefits of aerobic exercise in
glycemic control; for example, it reduces fasting glucose
and improves insulin sensitivity, both of which help to
alleviate the development of diabetes complications and
mortality [710]. Furthermore, a recent meta-analysis
demonstrated that aerobic exercise training is associated
with a decrease in HbA1c, insulin resistance, and fasting
* Lin Zhu
40848567@qq.com
1 School ofKinesiology, Shanghai University ofSport,
Shanghai200438, China
2 Guangzhou Sport University, Guangzhou510500, China
3 Department ofChild Health Care andRehabilitation,
Lanzhou University Second Hospital, Lanzhou730030,
China
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576 Aging Clinical and Experimental Research (2019) 31:575–593
1 3
glucose, and suggested that high-intensity aerobic exer-
cise is superior to lower intensity exercise in improving
cardiorespiratory fitness in T2D patients [11]. However,
the majority of patients do not typically achieve the rec-
ommended level of physical activity, despite the fact that
increases in physical activity level can improve glycemic
control and cardiorespiratory fitness in T2D patients. In
addition, a lack of time has been identified as one of the
key barriers preventing patients from performing sufficient
physical activity, which means that patients must partici-
pate in more time-efficient training programs to achieve
optimized outcomes.
High-intensity interval training (HIIT), therefore, appears
to be a feasible and time-efficient alternative exercise pro-
tocol to aerobic exercise: it involves alternating, repetitive
short bouts of high-intensity exercise interspersed with less
active or passive recovery periods. Numerous recent studies
have shown HIIT to be superior in improving health ben-
efits compared with lower intensity aerobic exercise in a
variety of populations [1214]. Støa etal. [15] found that
people with T2D who performed a supervised HIIT pro-
gram at an intensity of 85–95% of their maximal heart rate
with 52% VO2peak interval experienced a significant increase
in VO2peak and a reduction in hemoglobin A1c (HbA1c),
body weight, and body mass index (BMI) compared with
those who performed moderate-intensity continuous train-
ing (MICT), though no significant changes in insulin resist-
ance or blood lipid levels were found. Karstoft etal. [16]
compared the efficacy of HIIT with energy expenditure-
matched continuous-walking training in people with T2D
and observed greater improvements in VO2peak, body weight,
fat mass, and glycemic control with the former. Mitranun
etal. [17] also found that HIIT improved HbA1c, maximal
aerobic capacity, and other cardiovascular risk factors in
T2D patients, even if the total exercise time was reduced
to half of that recommended. Similar to the current study, a
recent meta-analysis by Jelleyman etal. demonstrated that
HIIT is more effective than MICT for improving insulin sen-
sitivity and cardiorespiratory fitness in healthy individuals
[18]. However, this study did not determine the suitability
of HIIT in individuals with T2D. Indeed, although a few
RCTs have demonstrated the efficiency of HIIT in the pre-
vention and treatment of T2D patients, no consensus has yet
been reached that HIIT is a superior training protocol for
the improvement of glycemic control, body composition,
and cardiorespiratory fitness compared with moderate-inten-
sity continuous aerobic training among patients with T2D.
Therefore, we performed a meta-analysis to determine the
impact of HIIT on body composition, glycemic control, and
cardiorespiratory fitness, and to compare it to that of MICT
and that of no intervention in randomized-controlled trials in
T2D patients, which we hope can provide clinical evidence
to enable patients to achieve optimal outcomes.
Patients andmethods
Search strategy
The databases which we searched included PubMed,
the Web of Science, EBSCO, Embase, and the Cochrane
Library. All of the databases were searched from their date
of inception until April 2018. We included only studies writ-
ten in English. We used combined key phrases and Medical
Subject Heading (MeSH) terms as follows: “type 2 diabetes
mellitus,” “diabetes mellitus, type II,” “type 2 diabetes,”
“T2D,” “T2DM,” “high-intensity interval training,” “high-
intensity aerobic interval exercise,” “high-intensity interval
training,” “aerobic interval training,” “high-intensity inter-
mittent exercise,” “HIT,” and “HIIT.” Supporting informa-
tion appendix in S1 gives a detailed description of the search
strategy. In addition, the reference lists of included studies
and reviews were also examined for additional potentially
eligible studies.
Inclusion andexclusion criteria
Type ofstudy
This review included studies with randomized-controlled tri-
als. We excluded matched controlled trial designs, uncon-
trolled trials, observational studies, and animal studies.
Type ofparticipant
The study participants were clinically diagnosed with type
2 diabetes. Patients with type 1 diabetes and gestational dia-
betes were excluded. There was no limitation on the age,
gender, or ethnicity of the study participants.
Intervention variables andoutcome measures
The studies included here were required to report at least one
outcome measure, measured at baseline and post-interven-
tion, and compared to either a moderate-intensity exercise
intervention or control group. The HIIT program had to be
prescribed at least two times per week for 4 weeks, with
moderate-intensity continuous training or another treatment
(e.g., drug therapy) as the control group.
Primary outcomes
Outcome measures included glycemic control (e.g., HbA1c,
fasting glucose, and fasting insulin); body composition [e.g.,
body weight, BMI, body fat (%), and waist circumference];
cardiorespiratory fitness (e.g., VO2peak). The criteria which
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577Aging Clinical and Experimental Research (2019) 31:575–593
1 3
we used complied with the PICO concept (patient/problem/
population; intervention; comparison/control/compara-
tor; outcome). For articles reported in more than two pub-
lications, only one full copy was used for meta-analysis.
Abstracts presented at academic conferences, case reports,
observational studies, examples of animal research, and
studies of which the full text could not be obtained were
excluded.
Evaluation ofbias andquality assessment
The risk of bias and methodological quality of the included
trials were assessed independently by two reviewers (Liu
and Li), who used the Cochrane Collaboration’s tool [19]
to check for concealed allocation, allocation concealment,
blinding, incomplete outcome data, selective reporting, and
other biases. Each reviewer was required to award one of
three grades (either unclear, low risk, or high risk) to each
item. The Grading of Recommendations Assessment, Devel-
opment, and Evaluation (GRADE) system [20] was used
to assess the quality of the evidence from very low to high
based on risk of bias, inconsistency, indirectness, impreci-
sion, and publication bias. A third reviewer was consulted
if any disagreement occurred.
Data extraction
The two investigators assessed each article’s title or abstract
for eligibility. When a disagreement happened, a third inves-
tigator participated in a discussion to reach a final consensus.
For studies that met the inclusion criteria, full papers were
obtained for further analysis. The two authors independently
extracted data from the published works using standard data
extraction forms. If there were any inconsistencies in the
process of data extraction, the two authors would check the
original text and reach an agreement through discussion or
through verification by a third author. Information on trial
design, characteristics of the patients, HIIT protocol, and
relevant results was noted according to a redesigned form.
We recorded the name of the first author and the year of
publication; the number of patients/participants and their
ages, gender, and BMIs; the duration of diagnosis; and the
experimental and control interventions (e.g., exercise inten-
sity and duration, interval intensity and duration, session
time, and duration in weeks). When data were insufficient or
inapplicable, we attempted to contact the authors by e-mail
or used an equation to reveal all available data.
Data analysis
The Review Manager software (RevMan 5.3; Cochrane,
London, UK) was used to conduct the meta-analysis. The
statistical heterogeneity of the treatment effect among the
included studies was assessed using the chi-squared test and
I2 test. A threshold of P < 0.10 was considered to be statisti-
cally significant and an I2 value > 50% was indicative of high
heterogeneity. We used the weighted mean difference (MD)
or standardized MD (SMD) with 95% confidence intervals
(CIs) for summary statistics and derived such for the com-
parison of HIIT with MICT or other treatment methods. MD
was used when all studies reported the same outcome using
the same scale, while SMD was used when studies reported
different units or scales for the outcome. If heterogeneity did
not exist between studies, we incorporated a fixed-effects
model approach to combined outcome measures. A random-
effects model was used when there was a large degree of
heterogeneity between studies. To account for within-group
intervention effect sizes, we used fixed-effects modeling to
estimate the change from baseline. Potential heterogeneity
sources were identified by sensitivity analyses conducted by
omitting one study successively and comparing the influence
of each study on the overall pooled estimate if I2 > 50%.
Data were analyzed using the change from baseline for
both groups. If the study did not contain change data, we
used the following two equations for conversion:
where M is the effect mean, M1 is the mean of the baseline,
and M2 is the end value mean;
where S is the standard deviation of the effect, S1 is the
standard deviation of the baseline value, S2 is the final stand-
ard deviation, and R is constant (0.4 or 0.5).
Results
Search results
The initial database searches returned a total of 484 articles
(PubMed, n = 84; EMBASE, n = 30; The Cochrane Library,
n = 63; EBSCO, n = 30; the Web of Science, n = 277) that
were each screened and evaluated for eligibility based on
their respective titles only. Following removal of duplicates,
421 articles underwent further identification and screen-
ing. In total, 378 non-relevant articles were excluded after
screening the titles and abstracts. Of the remaining articles,
43 were selected to be read in full. At this point, 30 addi-
tional articles were excluded for varying reasons (e.g., the
study was not randomized, there were reduplicative partici-
pants, the study was observational in nature, the research
was performed on animals, the study was presented at an
academic conference, and/or the study had no required data),
rendering a final sample of 13 papers. Figure1 describes the
study selection flow.
(1)
M
=
|
M
1
M
2|,
(2)
S
2=S2
1
+S2
2
2×R×S
1
×S
2,
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578 Aging Clinical and Experimental Research (2019) 31:575–593
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Characteristics ofincluded trials
A total of 345 participants were included in the analysis,
of which 163 (47.2%) participants underwent a HIIT inter-
vention. The characteristics of the study participants, the
HIIT training protocols used, and the main results from the
included studies are described in Table1. The countries or
regions of publication were mainly the United Kingdom
(n = 2), Norway (n = 2), the Republic of Korea (n = 1),
Chile (n = 1), Denmark (n = 2), France (n = 1), Thailand
(n = 1), Australia (n = 1), Italy (n = 1), and Canada (n = 1).
The main HIIT intervention ranged in duration from 11 to
16 weeks (16 weeks in 4 studies, 12 weeks in 8 studies,
and 11 weeks in 1 study) and occurred two-to-five times
weekly (median: three times). Total training duration per
session ranged from 30s to 4min, and interval duration
ranged from 30s to 3min.
Risk ofbias amongtheselected articles
The 13 studies were assessed for risk of bias; the evalu-
ation results are shown in Table2. Among the included
studies, the method of randomization was only clearly
stated in four studies [21, 25, 26, 28], while three reported
allocation concealment [25, 26, 28], five blinded partici-
pants or personnel [15, 16, 21, 23, 28], and three did not
employ assessor blinding [22, 24, 27]. Only one study did
not clearly state complete outcomes data and employed
selective reporting [22]; no other bias in all studies. The
evaluation of the overall quality of evidence and results is
shown in Table4, and the level of evidence for RCTs is
Fig. 1 Flowchart of the study
selection process Records identified though
database searching (n = 484)
Additional records identified
through other sources (n = 5)
30 full-text articles were excluded
for the following reasons:
Studydesign (20)
Reduplicative participants (2)
Included animal researches (2)
Participation in academic
conferences (2)
Required data not available(4)
Records after duplicates
removed(n = 421)
Studies included in
quantitative synthesis (n =13)
Studies included in
qualitative synthesis (n = 13)
Records screened (n =421)
Records excluded
for irrelevant studies
(n =378)
Full-text articles assessed
for eligibility (n = 43)
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579Aging Clinical and Experimental Research (2019) 31:575–593
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Table 1 Characteristics of the included trials
Article, year Country Main characteristics of the
subjects
HIIT MICT or CON No. of
patient
dropouts
Exercise intensity and
interval
Frequency and duration Exercise intensity Frequency and duration
Alvarez
2016 [21]
Chile HIIT: mean age was
45.6 ± 3.1 years, mean
duration of diagnosis was
3.14 ± 1.1 years, mean
BMI was 30.8 ± 1.0kg/m2,
n = 13
CON: mean age was
43.1 ± 1.5 years, mean
duration of diagnosis was
3.6 ± 1.1 years, mean BMI
was 30.4 ± 0.4kg/m2,
n = 10
Train: running at 90–100%
HRmax intensity for
30–120s; Interval: low-
intensity walking for
30–120s
2.2–37.5min/time, three
times per week for 16
weeks
CON: non-exercise 5
Hollekin
2014 [22]
Norway Total of 47 patients
55.9 ± 6.0 years; 36%
female; mean dura-
tion of diagnosis was
3.6 ± 2.5years
HIIT: mean BMI was
30.2 ± 2.8kg/m2, 5% in
mild stage, 90% in moder-
ate stage, 5% in severe
stage, n = 24
MICT: mean BMI was
29.7 ± 3.7kg/m2, 29.4%
in mild stage, 70.6% in
moderate stage, n = 23
Protocol was 4×4min
exercise at 90–95% HRmax
with 3min of low-inten-
sity exercise at 70% HRmax
40min /bout; three times
per week for 12 weeks
MICT: Moderate-intensity
aerobics training
210min per week for 12
weeks
10
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580 Aging Clinical and Experimental Research (2019) 31:575–593
1 3
Table 1 (continued)
Article, year Country Main characteristics of the
subjects
HIIT MICT or CON No. of
patient
dropouts
Exercise intensity and
interval
Frequency and duration Exercise intensity Frequency and duration
Karstoft
2013 [16]
Denmark HIIT: mean age was
57.5 ± 2.4 years, 41.7%
female, mean BMI was
29.0 ± 1.3kg/m2, mean
duration of diagnosis was
3.5 ± 0.7 years, n = 12
MICT: mean age was
60.8 ± 2.3 years, 33.3%
female, mean BMI was
29.9 ± 1.6kg/m2, mean
duration of diagnosis was
6.2 ± 1.5 years, n = 12
CON: mean age was
60.8 ± 2.3 years, 37.5%
females, mean BMI was
29.7 ± 1.9kg/m2, mean
duration of diagnosis was
4.5 ± 1.5 years, n = 8
Alternating 3min intervals
of fast (≥ 70% of VO2peak)
and slow (40% of VO2peak)
walking
Five times per week,
60min/time for 4 months
MICT: walking at ≥ 55%
VO2peak 60min/session
CON: non-exercise
Five times per week, for 4
months
0
Lee 2015 [23] Korea Mean age was 15.3 ± 2.2
years, mean BMI was
24.0 ± 3.8kg/m2, mean
duration of diagnosis was
4.0 ± 2.2 years, n = 20
Exercise at ≥ 80% HRR,
train program includ-
ing 30-s sprint and 30-s
recovery
400 Kcal/session, three
sessions per week for 12
weeks
MICT: Exercise at ≤ 40%
HRR, 200kcal/session
Six sessions per week for
12 weeks
0
Maillard
2016 [24]
France Included 16 postmenopausal
women with T2D, mean
age was 69 ± 1 years, mean
BMI was 31 ± 1kg/m2
HIIT: mean age was
68.2 ± 1.9 years, mean
BMI was 32.6 ± 1.7kg/
m2, N = 8
MICT: mean age was
70.1 ± 2.4 years, mean
BMI was 29.7 ± 1.2kg/
m2, n = 8
Repeated cycles of sprinting
for 8s (at around 80%
HRmax) followed by pedal-
ing slowly (20–30rpm)
for 12s (maximum of 60
cycles per 20-min session)
Two times per week for 16
weeks
MICT: Exercise at 55–60%
HRR for 40min
Two times/week, 16 weeks 1
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581Aging Clinical and Experimental Research (2019) 31:575–593
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Table 1 (continued)
Article, year Country Main characteristics of the
subjects
HIIT MICT or CON No. of
patient
dropouts
Exercise intensity and
interval
Frequency and duration Exercise intensity Frequency and duration
Mitranun
2014 [17]
Thailand Total of 43 adults with T2D
(64.4% females), HIIT:
mean age was 61.2 ± 2.8
years, mean BMI was
29.6 ± 0.5kg/m2, mean
duration of diagnosis was
19.5 ± 1.5 years; n = 14.
MICT: mean age was
61.7 ± 2.7 years, mean
BMI was 29.4 ± 0.7kg/m2,
mean duration of diagnosis
was 20.5 ± 1.5 years;
n = 14. CON: mean age
was 60.9 ± 2.4 years, mean
BMI was 29.7 ± 0.4kg/m2,
mean duration of diagnosis
was 21.1 ± 2.32 years;
n = 15
Protocol was 1-min high-
intensity exercise at
50–85% VO2peak with
4-min low-intensity at
50–60% VO2peak interval
20min /session, three
sessions per week for 12
weeks
MICT: exercise intensity
at 50–60% VO2peak for
25–30min
Three times/week, 12 weeks
CON: non-exercise
2
Ramos
2016 [25]
Australia HIIT: mean weight was
99 ± 18kg, n = 9
MICT: mean weight was
98 ± 17kg, n = 6
Protocol was 4*4min bouts
at 85–95% HRmax, interval
with 3min of active recov-
ery at 50–70% HRmax
38min per session, 3 times
per week for 16 weeks
MICT: 30min at 60–70%
HRpeak
5 times/week, 16 weeks 0
Støa
2017 [15]
Norway HIIT: mean age was 59 ± 11
years, mean BMI was
32.0 ± 4.7kg/m2, mean
duration of diagnosis was
9 ± 7 years, n = 19
MICT: mean age was
59 ± 10 years, mean BMI
was 31.1 ± 4.5kg/m2,
mean duration of diagnosis
was 6 ± 5 years, n = 19
Protocol was 4*4min
of walking or uphill at
85–95% of HRmax
Three times per week for 12
weeks
MICT: 60-min walking at
70–75% of HRpeak
Three times per week for 12
weeks
5
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582 Aging Clinical and Experimental Research (2019) 31:575–593
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Table 1 (continued)
Article, year Country Main characteristics of the
subjects
HIIT MICT or CON No. of
patient
dropouts
Exercise intensity and
interval
Frequency and duration Exercise intensity Frequency and duration
Terada
2013 [26]
Canada HIIT: mean age was 62 ± 3
years, mean BMI was
28.4 ± 4.1kg/m2, 50%
female, mean duration of
diagnosis was 6 ± 4 years,
n = 8
MICT: mean age was 63 ± 5
years, mean BMI was
33.1 ± 4.5kg/m2, 42.9%
female, mean duration of
diagnosis was 8 ± 74 years,
n = 7
HIIT protocol involved
alternating 1-min intervals
100% VO2peak with 3-min
recovery intervals at 20%
VO2peak
30–60min/day, 5 days per
week for 12 weeks
MICT: continuous exer-
cise at 40% VO2peak,
30–60min/day
5 days per week for 12
weeks
0
Backx
2011 [27]
UK Involved 15 males and 4
females; total median age
was 59.6 (44.0–69.0) years
HIIT: median BMI was 30.0
(25.3–40.1) kg/m2, n = 10
MICT: median BMI was
32.3 (26.4–40.5) kg/m2,
n = 9
Protocol was 1–2min at
40–50% HRR and 1, 2, or
3min at 80–90% HRR
60min/day, 3 days per week
for 12 weeks
MICT: Exercise at moder-
ate-to-high-intensity for
30min
Five times/week, 12 weeks 2
Cassidy
2016 [28]
UK HIIT: mean age was 61 ± 9
years, mean BMI was
31 ± 5kg/m2, mean dura-
tion of diagnosis was 5 ± 3
years, n = 12
MICT: mean age was 59 ± 9
years, mean BMI was
32 ± 6kg/m2, mean dura-
tion of diagnosis was 4 ± 2
years, n = 11
Training: Pedal
cadence > 80 rev/min,
ranching a RPE 16–17
(very hard); interval:
3-min recovery cycle
Three sessions per week for
12 weeks
Non-exercise 5
Bellia 2017 [29] Italy HIIT: mean age was
58.8 ± 7.9, mean BMI was
27.7 ± 2.8kg/m2, mean
duration of diagnosis was
5.9 ± 4.4 years, n = 11
CON: mean age was
56.3 ± 6.4, mean BMI was
29.9 ± 3.4kg/m2, mean
duration of diagnosis was
3.4 ± 3.7 years, n = 11
Protocol involved a 4-min
walk at 75–80% HRmax to
be repeated two-to-four
times, interval with 3-min
active recovery at 45–50%
HRmax
Two–three times per week
for 12 weeks
MICT: protocol was 10,000 steps per day or 70,000 steps
per week for 12 weeks
7
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583Aging Clinical and Experimental Research (2019) 31:575–593
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downgraded due to inconsistency and imprecision in most
of the studies.
Effects ofHIIT onbody composition
The included studies assessed body weight (11/13; 84.6%);
BMI (11/13; 84.6%); body fat (6/13; 46.2%); waist circum-
ference (7/13; 53.8%) as outcomes. Of these, 8/11 (72.7%
of body weight studies); 8/11 (72.7% of BMI studies); 5/6
(83.3% of body fat studies); 6/7 (85.7% of waist circumfer-
ence studies) compared HIIT to MICT. The meta-analyses
showed (Table3) a significant reduction in body weight of
1.22kg [95% CI − 2.23 to − 0.18, P = 0.02] for patients in
the HIIT group as compared with those in the MICT group.
Furthermore, in comparison with baseline, there was a
reduction in BMI of 0.85kg/m2 (95% CI − 1.57 to − 0.12,
P = 0.02) (Table3), and, as compared with the MICT group,
the reduction was 0.40kg/m2 (95% CI − 0.78 to − 0.02,
P = 0.04) (Table3). In addition, as compared with baseline,
there was a reduction in body fat of 1.86% (95% CI − 3.68 to
− 0.04, P = 0.02) (Table3), but the reduction was not statisti-
cally significant as compared with that in the MICT group.
In addition, there was no significant difference in the waist
circumference reduction following HIIT versus MICT or at
baseline (Table3).
Effects ofHIIT onglycemic control
Ten studies with 220 patients assessed HbA1c. Of these,
nine studies compared changes in HbA1c in HIIT groups to
those in MICT groups, while only three studies compared
such to changes in CON groups. Relative to baseline, there
was a significant reduction in HbA1c (SMD: −0.29, 95%
CI − 0.55 to − 0.04, P = 0.02) (Fig.2a; Table3). Compared
with MICT, the reduction was 0.37% (95% CI − 0.55 to
− 0.19, P < 0.0001, Fig.2a). However, in comparison with
a control intervention, a non-significant change in HbA1c
of -0.39% (95% CI − 0.81 to 0.02, P < 0.06, Fig.2b) was
found. As compared with baseline, there was a significant
reduction in fasting insulin (SMD: −0.46, 95% CI − 0.81 to
− 0.11, P = 0.01, Table3). However, this reduction was not
significantly different as compared with that in the control
intervention or MICT groups (Table3). No significant dif-
ference in the fasting glucose or HOMA-IR (homeostatic
model assessment of insulin resistance) was found for par-
ticipants in the HIIT group as compared with those in the
MICT group (Table3). We further used sensitivity analysis
in HOMA-IR because of the larger heterogeneity (I2 = 73%)
within the group. The results of sensitivity analysis showed
that the heterogeneity (I2 = 0%) was significantly reduced
after exclusion of Lee 2015, but there was no significant
change in results.
Table 1 (continued)
Article, year Country Main characteristics of the
subjects
HIIT MICT or CON No. of
patient
dropouts
Exercise intensity and
interval
Frequency and duration Exercise intensity Frequency and duration
Winding
2018 [30]
Denmark HIIT: mean age was
54 ± 6, mean BMI was
28.1 ± 3.5kg/m2, mean
duration of diagnosis was
8 ± 4 years, n = 13
MICT: mean age was 58 ± 8
years, mean BMI was
27.4 ± 3.1kg/m2, mean
duration of diagnosis was
6 ± 4 years, n = 12
CON: mean age was
57 ± 7, mean BMI was
28 ± 3.5kg/m2, mean dura-
tion of diagnosis was 7 ± 5
years, n = 7
Training: initiated with a
20min of cycling consist-
ing of cycles of 1min
at 95% Wpeak and 1min
of active recovery (20%
Wpeak) was performed
3 days per week for 11
weeks
MICT: 40min of cycling at
50% of Wpeak 3 days/week, 11 weeks 3
RCT randomized-controlled trial, MCT Matched controlled trial designs, HRmax maximal heart rate, HIIT high-intensity interval training, MICT moderate-intensity continuous training, CON
control, HRR heart rate reserve, RPE rating of perceived exertion
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584 Aging Clinical and Experimental Research (2019) 31:575–593
1 3
Effects ofHIIT onlipid control
Seven studies assessed low-density lipoprotein (LDL) cho-
lesterol as an outcome. Of these, five studies compared the
change in the HIIT group to that in the control group and
six studies compared the change in the HIIT to that in the
MICT group. There was also a significant reduction in LDL
cholesterol (MD: −0.25mmol/L 95% CI − 0.46 to − 0.04,
P = 0.02) with HIIT versus with the MICT group (Table3).
Unfortunately, there was no significant change in total cho-
lesterol as compared with both the control and MICT groups
and a similar result was found with respect to high-density
lipoprotein (HDL) cholesterol. LDL cholesterol did not dif-
fer significantly between the HIIT group and the control
group. Because studies comparing HIIT with control inter-
ventions in relation to LDL and HDL cholesterol showed
significantly more heterogeneity, we conducted sensitivity
analysis that showed that the studies heterogeneity changed
significantly (I2 = 20% in LDL cholesterol, I2 = 0 in HDL
cholesterol) after the removal of Alvarez 2016, but there
were no significant changes in the results.
Effects ofHIIT oncardiorespiratory fitness
Cardiorespiratory fitness as measured using absolute VO2peak
(L/min) and relative VO2peak (ml/kg/min) was analyzed
using data from seven studies representing a total of 219
patients. As compared with baseline, there was a 4.75ml/
kg/min (95% CI 2.94 to 6.56, P < 0.0001) (Fig.3a; Table2)
or 0.35L/min (95% CI 0.17 to 0.53, P = 0.0001) increase in
VO2peak with HIIT (Fig.4a; Table3). In addition, there was
a 4.12ml/kg/min (95% CI 2.66 to 5.57, P < 0.0001) (Fig.3b)
or 0.24L/min (95% CI 0.10 to 0.37, P = 0.0005) (Fig.4b)
increase in VO2peak with HIIT over control interventions.
The random-effects model showed (Fig.4c) a significant
improvement in absolute VO2peak of 0.37L/min (95% CI
0.28 to 0.45, P < 0.0001) for patients in HIIT group versus
those in the MICT group and there was a similar increase
seen with respect to relative VO2peak (MD: 3.37ml/kg/min,
95% CI 1.88 to 4.87, P < 0.0001) (Fig.3c). However, there
existed moderate heterogeneity in this analysis (I2 = 48%)
and the results should be interpreted with caution (Table4).
Discussion
The purpose of this study was to evaluate the effectiveness
of HIIT on body composition, glycemic control, and car-
diorespiratory fitness in patients with T2D; to observe the
difference in such compared with MICT or non-exercise;
and to provide information on an ideal time-efficient physi-
cal activity program. The principal finding of the current
meta-analysis was that HIIT was more efficient than MICT
in increasing VO2peak in T2D patients; they also found that
reduction of BMI, body weight, and HbA1c (%) was less
conclusive because of low quality of the evidence.
Excess weight and obesity are important risk factors for
the occurrence of T2D and contribute to the development of
insulin resistance in obese individuals [31, 32]. Even with a
body weight that falls within the normal range, individuals
with an abnormal BMI and waist circumference can also
present with an increased risk of abnormal glucose metabo-
lism [33]. Our work showed that HIIT improved body com-
position, reducing BMI significantly by 0.85kg/m2 and
reducing body fat by 1.86%. Notably, both body weight
and BMI were significantly decreased compared with the
Table 2 Risk-of-bias assessment for the included studies
Study Random sequence
generation
Allocation
concealment
Blinding Incomplete
outcome data
Selective reporting Other bias
Participants or
personnel
Outcome
assessment
Alvarez [21]Low Unclear Low Low Low Low Low
Hollekin [22] Unclear Unclear Unclear Unclear Unclear Unclear Low
Karstoft [16] Unclear Unclear Low Low Low Low Low
Lee [23] Unclear Unclear Unclear Low Low Low Low
Maillard [24] Unclear Unclear Unclear Unclear Low Low Low
Mitranun [17] Unclear Unclear Unclear Low Low Low Low
Ramos [25]Low Low Low Low Low Low Low
Støa [15] High High Low Low Low Low Low
Terada [26]Low Low High Low Low Low Low
Backx [27] High Unclear Unclear Unclear Low Low Low
Cassidy [28]Low Low Low Low Low Low Low
Bellia [29] Unclear Unclear Unclear Low Low Low Low
Winding [30] Unclear Unclear Unclear Low Low Low Low
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585Aging Clinical and Experimental Research (2019) 31:575–593
1 3
MICT group, which suggests that HIIT may be more effec-
tive for improving body composition (even in the absence of
changes in body fat and waist circumference) in individuals
with T2D. The underlying mechanism of HIIT-induced body
weight loss may be related to the consumption and release
of fat from visceral fat stores. Maillard etal. [24] studied
and compared the effects of HIIT and MICT on abdominal
fat in postmenopausal women with T2D, and observed that
only HIIT reduced the subcutaneous and visceral fat mass
significantly following 16 weeks of training. Cassidy etal.
Table 3 Effect of HIIT on body composition, glycemic control, lipid control, and cardiorespiratory fitness in patients with T2D
ES effect sizes, CI confidence interval, MD mean difference, SMD standardized mean difference, ND not enough data
Body composition Within groups Compared to CON Compared to MICT
Body weight N11 6 8
ES (95% CI) MD: −1.65 [−4.76, 1.46] MD: −0.78 [−2.36, 0.80] MD: −1.22 [−2.23, −0.18]
I2 (%) 0 0 0
BMI N11 4 8
ES (95% CI) MD: −0.85 [−1.57, −0.12] MD: −0.80 [−1.86, 0.27] MD: −0.40 [−0.78, −0.02]
I2 (%) 0 0 0
Body fat (%) N6 ND 5
ES (95% CI) MD: −1.86 [−3.68, −0.04] MD: −0.50 [−1.18, 0.19]
I2 (%) 0 0
Waist circumference N7 ND 6
ES (95% CI) MD: −2.23 [−5.00, 0.55] MD: −0.15 [−1.21, 0.91]
I2 (%) 0 0
Glycemic control
HbA1c (%) N10 3 9
ES (95% CI) MD: −0.29 [−0.55, −0.04] MD: −0.39 [−0.81, 0.02] MD: −0.37 [−0.55, −0.19]
I2 (%) 0 0 0
Fasting glucose N9 5 8
ES (95% CI) MD: −0.41 [−0.91, 0.09] SMD: −0.31 [−0.69, 0.06] MD: 0.10 [−0.84, 0.65]
I2 (%) 0 0 0
Fasting insulin N6 5 4
ES (95% CI) SMD: −0.46 [−0.81, −0.11] SMD: −0.46 [−0.91, 0.02] SMD: −0.19 [−0.58, 0.20]
I2 (%) 41 26 0
HOMA-IR N7 4 6
ES (95% CI) MD: −0.43 [−1.18, 0.32] MD: −0.18 [−0.79, 0.42] MD: 0.13 [−0.10, 0.36]
I2 (%) 73 0 0
Lipid control
Total cholesterol N8 6 7
ES (95% CI) SMD: −0.13 [−0.42, 0.15] SMD: 0.02 [−0.32, 037] MD: −0.18 [−0.44, 0.07]
I2 (%) 0 9 0
HDL cholesterol N11 5 9
ES (95% CI) SMD: 0.20 [−0.07, 0.48] SMD: 0.60 [−0.26, 1.45] MD: −0.04 [−0.10, 0.02]
I2 (%) 39 83 0
LDL cholesterol N 7 5 6
ES (95% CI) SMD: −0.15 [−0.44, 0.13] MD: −0.60 [−1.74, 0.54] MD: −0.25 [−0.46, −0.04]
I2 (%) 0 52 0
Cardiorespiratory fitness
VO2peak (ml/kg/min) N7 2 7
ES (95% CI) MD: 4.75 [2.94, 6.56] MD: 4.12 [2.66, 5.57] MD: 3.37 [1.88, 4.87]
I2 (%) 0 0 48
VO2peak (L/min) N5 2 6
ES (95% CI) MD: 0.35 [0.17, 0.53] MD: 0.24 [0.10, 0.37] MD: 0.37 [0.28, 0.45]
I2 (%) 0 0 36
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586 Aging Clinical and Experimental Research (2019) 31:575–593
1 3
[28] reported, in their randomized study, that there was a
39% relative reduction in liver fat following HIIT perfor-
mance and observed that there was a significant correlation
with changes in HbA1c and 2-h glucose. Moreover, Karstoft
etal. [16] found that patients with T2D had greater oxygen
consumption during HIIT training than did those who per-
formed MICT, suggesting that this may be responsible for
their greater weight loss. Recent studies have shown that
the positive effects of exercise on body composition may be
related to the improvement of glycemic control. For exam-
ple, in a long-term randomized trial, Senechal etal. [34]
found that changes in HbA1c were associated with changes
in body weight, waist circumference, and trunk fat mass
in individuals with T2D. Notably, however, although this
review shows that HIIT has favorable effects on body fat
reduction in individuals with T2D, the effects of HIIT on
blood lipids were limited. Only LDL cholesterol showed
significantly lower levels after HIIT than after MICT, while
total cholesterol and HDL cholesterol did not. Thus, more
studies are required to determine whether HIIT could be a
successful training program for lipid control in T2D patients.
HbA1c is not only the most widely used indicator of
glucose: it is also an important risk factor of cardiovas-
cular disease in patients with T2D [35, 36]. The previous
studies have shown that if HbA1c levels are reduced by
1%, the risk of microvascular complications is reduced by
Fig. 2 Forest plot for change in of HbA1c (%), a before and after (within-group) high-intensity interval training (HIIT), b between HIIT and
control (CON) intervention, and c between HIIT and moderate-intensity training (MICT)
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587Aging Clinical and Experimental Research (2019) 31:575–593
1 3
37% and that of death related to diabetes can be reduced
by 21% [35]. A recent meta-analysis has shown that an
increase of 100min in physical activity per week was asso-
ciated with an average change of −0.16% of HbA1c in
individuals with T2D and pre-diabetes subjects [37]. In
our meta-analysis, HbA1c (%) was found to be lower after
HIIT than at baseline (SMD: −0.29, 95% CI −0.55 to
−0.04). Similar to our findings, a recent meta-analysis of
RCTs by Grace etal. identified the positive effects of aero-
bic exercise in reducing HbA1c levels over with controls
[11]. HIIT showed a 0.37% greater reduction of HbA1c
than MICT, which means that HIIT may have additional
benefits on glycemic control. This is inconsistent with the
findings of a meta-analysis conducted by Jelleyman etal.
[18], which found that, while HIIT can reduce the levels
of HbA1c in patients with diabetes and metabolic syn-
drome, there is no significant difference in reduction ver-
sus with continuous training. Furthermore, in a previous
review with a meta-analysis, it was concluded that exercise
intensity was a better predictor of weight MD in HbA1c
than exercise volume in T2D patients [38]. Unfortunately,
we noted no difference in fasting glucose, fasting insulin,
or insulin resistance changes in patients following HIIT as
compared with the CON and MICT groups, even though
the previous studies have shown that the effects of aerobic
training on insulin intensity are more closely influenced
by high-exercise intensity than by low- or moderate-inten-
sity exercise [39]. The inconsistent results could partly
be explained by the difference among methods used to
measure insulin sensitivity, as well as the difference in
the baseline of glycemic control. Further research would
need to include data on the HIIT intervention program
(e.g., training intensity, duration of interval time, fre-
quency of training, and total duration) and the character-
istics of patients (especially with respect to age, duration
Fig. 3 Forest plot for change in VO2peak (ml/kg/min), a before and after (within-group) high-intensity interval training (HIIT), b between HIIT
and control (CON) intervention, and c between HIIT and moderate-intensity training (MICT)
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588 Aging Clinical and Experimental Research (2019) 31:575–593
1 3
of diabetes, and the baseline glycemic control), which all
impact trial results.
Both VO2peak and HbA1c are important predictors of car-
diovascular events in T2D patients [35], and the previous
studies have shown that low cardiorespiratory fitness was
associated with an increased risk for impaired glycemic con-
trol [40, 41]. Aerobic exercise training represents an effec-
tive means to improve VO2peak and HbA1c, and a previous
meta-analysis has revealed that aerobic exercise intensity
is the primary stimulus for improved VO2peak in people
with T2D [11]. Our study further compared the difference
between HIIT and MICT in increasing peak VO2 and found
that the improvement of 3.37ml/kg/min in relative VO2peak
and 0.37L/min in absolute VO2peak following HIIT is supe-
rior to those seen with MICT. Our findings are similarly to
those from other recent studies. A meta-analysis focused
mainly on cardiac patients by Xie etal. [42] showed that
HIIT is more effective than continuous training in improv-
ing VO2peak [MD: 1.76ml/kg/min, 95% CI 1.06 to 2.46ml/
kg/min]. Another systemic analysis analyzing 65 studies by
Batacan etal. [43] revealed that HIIT yielded a significant
increase in VO2peak by a large amount in normal-weight pop-
ulations and a medium effect in overweight/obese popula-
tions, with an aggregate improvement of 3.8 and 4.43ml/
kg/min, respectively. A more recent meta-analysis includ-
ing 594 coronary artery disease patients by Gomes-Noto
etal. [44] reported that a higher improvement in VO2peak
(MD: 1.3ml/kg/min, 95% CI 0.6 to 1.9ml/kg/min) was seen
with HIIT versus with MICT. The underlying physiologi-
cal mechanisms of HIIT that improve peak VO2 could not
be ascertained from the present study, but may involve a
combination of central and peripheral adaptations, includ-
ing an increase in cardiac output, an improvement in vas-
cular/endothelial function, and increased muscle oxidation,
which together promote the enhanced availability, extrac-
tion, and use of oxygen during exercise [45, 46]. Revdal
etal. [47] studied the impact of HIIT on cardiac structure
and function in T2D patients, and observed a 12% relative
increase in left-ventricular wall mass and increased end-
diastolic blood volume, thus demonstrating improvements
Fig. 4 Forest plot for change in VO2peak (L/min), a before and after (within-group) high-intensity interval training (HIIT), b between HIIT and
control (CON) intervention, and c between HIIT and moderate-intensity training (MICT)
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589Aging Clinical and Experimental Research (2019) 31:575–593
1 3
Table 4 Summary of GRADE’s approach to rating quality of evidence
Outcomes Quality assessment
Comparison Participants
(studies) follow
up
Risk of bias Inconsistency Indirectness Imprecision Publication bias Overall quality of
evidence
Body weight MICT 185 (eight stud-
ies)
None None Serious Serious Undetected ⊕⊕⊝⊝ Low due
to indirectness
and imprecision
CON 136 (six studies) None None Serious Serious Undetected ⊕⊕⊝⊝ Low due
to indirectness
and imprecision
BMI MICT 207 (eight stud-
ies)
None None Serious Serious Undetected ⊕⊕⊝⊝ Low due
to indirectness
and imprecision
CON 72 (three stud-
ies)
None None Serious Serious Undetected ⊕⊕⊝⊝ Low due
to indirectness
and imprecision
Body fat (%) MICT 138 (five stud-
ies)
Serious Very serious None Serious Undetected ⊕⊝⊝⊝ Very low
due to risk of
bias, incon-
sistency and
imprecision
CON ND ND ND ND ND ND ND
Waist circum-
ference
MICT 140 (six studies) None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsistency
and imprecision
CON ND ND ND ND ND ND ND
HbA1c (%) MICT 209 (nine stud-
ies)
None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsist-
ency, impreci-
sion
CON 63 (three stud-
ies)
None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsistency
and imprecision
Fasting glucose MICT 162 (eight stud-
ies)
None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsistency
and imprecision
CON 114 (five stud-
ies)
None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsistency
and imprecision
Fasting insulin MICT 103 (five stud-
ies)
None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsistency
and imprecision
CON 85 (four studies) None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsistency
and imprecision
HOMA-IR MICT 182 (seven stud-
ies)
None Very serious None Serious Undetected ⊕⊝⊝⊝ Very low
due to incon-
sistency and
imprecision
CON 99 (four studies) None Very serious None Serious Undetected ⊕⊝⊝⊝ Very low
due to incon-
sistency and
imprecision
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590 Aging Clinical and Experimental Research (2019) 31:575–593
1 3
in systolic function, as indicated by raised stroke volume
and left-ventricular ejection fraction. A similar finding was
found by Hollekin etal. [22], who observed that both MICT
and HIIT groups showed improved diastolic function at rest,
but that the HIIT group showed greater improvement than
did the MICT group. Moreover, Little etal. [48] found that
people with T2D who performed six sessions of low-volume
HIIT at an intensity of 90% of the maximal heart rate with
60-s rest over 2 weeks experienced an increase in maximal
activity of citrate synthesis and skeletal muscle mitochon-
drial protein content, suggesting that the increases in skel-
etal muscle mitochondrial content and function following
low-volume HIIT may be contributing factors to improved
VO2peak.
Table 4 (continued)
Outcomes Quality assessment
Comparison Participants
(studies) follow
up
Risk of bias Inconsistency Indirectness Imprecision Publication bias Overall quality of
evidence
Total choles-
terol
MICT 165 (seven stud-
ies)
None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsistency
and imprecision
CON 137 (six studies) None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsistency
and imprecision
HDL choles-
terol
MICT 204 (nine stud-
ies)
None Serious None Serious Reporting bias
strongly sus-
pected
⊕⊝⊝⊝ Very
low due to
inconsistency,
imprecision and
publication bias
CON 114 (five stud-
ies)
None Serious None Serious Reporting bias
strongly sus-
pected
⊕⊝⊝⊝ Very
low due to
inconsistency,
imprecision and
publication bias
LDL MICT 150 (six studies) None Serious None Serious Reporting bias
strongly sus-
pected
⊕⊝⊝⊝ Very
low due to
inconsistency,
imprecision and
publication bias
CON 114 (five stud-
ies)
None Very serious None Serious None ⊕⊝⊝⊝ Very low
due to incon-
sistency and
imprecision
VO2peak (L/
min)
MICT 159 (six studies) None Serious None Serious Undetected ⊕⊕⊕⊝ Moder-
ate due to
inconsistency,
imprecision and
large effect
CON 40 (two studies) None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsistency
and imprecision
VO2peak (ml/
kg/min)
MICT 182 (seven stud-
ies)
Serious Serious None Serious Undetected ⊕⊕⊕⊝ Moder-
ate due to
inconsistency,
imprecision and
large effect
CON 40 (two studies) None Serious None Serious Undetected ⊕⊕⊝⊝ Low due
to inconsistency
and imprecision
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591Aging Clinical and Experimental Research (2019) 31:575–593
1 3
Strengths andlimitations
Our meta-analysis of randomized trials has several strengths.
First, to our knowledge, this is the first existing systematic
review to compare the effects of HIIT and MICT or non-
exercise on glycemic control (e.g., HbA1c, insulin, and fast-
ing glucose); body composition (e.g., body weight, body fat,
BMI, and waist circumference); and cardiorespiratory fitness
(e.g., VO2peak) among people with T2D. Second, this system-
atic review involved a large number of literature searches by
two reviewers who independently screened studies, assessed
their quality, and extracted data to decrease publishing bias
and increase credibility.
However, some limitations were still present in our
evaluation. First, there are some inconsistencies among the
included studies with respect to HIIT protocols and MICT
protocols, which may have affected the results obtained
with respect to the intervention and control groups. Second,
considering the low quality of evidence, these results may
have some limitations in guiding clinical applications. Third,
an important limitation is that most of the included studies
reported the pre- and post-intervention parameters but not
the differences between the baselines. Therefore, consider-
ing the different baseline values that may be present between
the intervention and control groups in some studies, we used
equations to calculate the mean difference whenever it was
not reported to address the discrepancy of the baseline in
each group, and this could have resulted in a bias. Fourth,
the results of this meta-analysis are limited by the lack of
high-quality studies and the small number of patients in each
included study. Only four of the included studies clearly
indicated random sequence generation, while three studies
reported allocation concealment, and five studies blinded
participants in their experimental procedures.
Conclusions
In conclusion, we here demonstrated that HIIT is an effective
strategy for improving cardiorespiratory fitness in patients
with T2D, preferable to MICT. Results related to other
parameters associated with the prognosis of T2D, such as
HbA1c, body weight, and BMI, were not conclusive. This
review can still provide some suggestions for the clinical
application of HIIT in T2D patients. Future studies should
investigate the effects of HIIT in T2D patients through mul-
ticenter RCTs with large sample sizes over the long term.
Acknowledgements We would like to thank LetPub (http://www.letpu
b.com) for providing linguistic assistance during the preparation of
this manuscript.
Author contributions Jing-xin Liu contributed to study conception and
design, drafting the submitted article, and critically revising the draft
for important intellectual content. Lin Zhu revised the draft critically
for important intellectual content and gave final approval of the version
for publication. Pei-jun Li, Ning Li, and Yan-bing Xu contributed to
acquisition, analysis, and interpretation the data. All authors contrib-
uted at all stages of this study, gave final approval of the version for
publication, and agree to be accountable for all aspects of the work.
Funding This work was supported by the National Planning Office of
Philosophy and Social Science of China (No. 18BTY075), the research
projects of the Social Science and Humanity on Young Fund of the
Ministry of education of China (No. 13yjc890050), the research pro-
jects of the Department of Education of Guangdong Province (No.
2015KTSCX079), the research projects of the Department of Science
and Technology of Guangdong Province (No. 2015A020219010 and
No. 2014A020220010).
Compliance with ethical standards
Conflict of interest The authors declare that there is no conflict of in-
terest regarding the publication of this paper.
Statement of human and animal rights This review does not contain
any experiments involving human participants or animals performed
by any of authors.
Informed consent For this review, formal consent forms were not
required.
Open Access This article is distributed under the terms of the Crea-
tive Commons Attribution 4.0 International License (http://creat iveco
mmons .org/licen ses/by/4.0/), which permits unrestricted use, distribu-
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... Evidence shows that HIIT significantly improves glycemic control (HbA1c) [33,34], even in heterogenic age groups. For instance, SIT and HIIT, even in lower training volume than endurance exercise, have better effects than endurance exercise on fitness and glycemic control [35]. ...
... This author concluded that HIIT could be an optional exercise strategy to improve health and metabolic problems, including for people who do not have time; SIT is recommended as an alternative to HIIT and MICT. In a recent study, [33], working with patients diagnosed with type II diabetes, without limitations of age, sex, or ethnicity, demonstrated that the group that practiced HIIT had a significant reduction in LDL, there was no significant change in total cholesterol compared to the control and MICT groups, and authors found a similar result concerning high lipoprotein cholesterol density. Therefore, HIIT is an effective strategy to improve cardiorespiratory fitness in patients with type II Diabetes (T2D) with more pronounced effects than MICT. ...
Article
Full-text available
Introduction: Physical exercise can improve glucose metabolism; however, the best type, volume, intensity, and frequency aren't knowledge. High-Intensity Interval Training (HIIT), an emergent exercise type implicated as a short time-efficient exercise to improve metabolic health, needs more investigation regarding the traditional Moderate-Intensity Continuous Training (MICT). Objective: To identify the effects of MICT and HIIT on glycemic control of older people with glucose metabolism impairments. Methods: Our research question was based on the PICO model and the systematic review of the literature according to the guidelines of the preferred report items for systematic reviews and PRISMA meta-analyses. An extensive search was conducted in the Web of Science, PubMed, and Scielo databases. Only English language papers were included. The keywords used were "HIIT and metabolism of the elderly", "HIIT and glucose metabolism of the elderly", and "MICT and metabolism of the elderly", which were crossed with the Boolean operators "AND" and "OR" or both according to the guidelines of the PRISMA. Results: Seventy papers were retrieved in the initial search. After applying all inclusions and exclusion parameters, 63 articles were excluded. In the end, six papers were classified as eligible for this study. All data categorically demonstrates that both HIIT and MICT can improve glucose metabolism with a larger effect size towards the HIIT model after the meta-analysis, pointing to HIIT as the most effective strategy. Conclusion: Both modalities can improve glucose metabolism in the elderly with a clear advantage for HIIT over MICT.
... La modalité « vélo » semblait plus efficace que la course à pied pour réduire la masse grasse abdominale. A l'inverse, dans leur méta-analyse incluant hommes et femmes, Maillard et al., (2018) (Maillard et al., 2016 ;Liu et al., 2019 ;Bartlett et al., 2020). Au sein de populations variées (où les valeurs de glycémie, d'insulinémie ou d'HbA1c ne sont pas des facteurs d'inclusion), les résultats sont moins consensuels (Trapp et al., 2008 ;Boutcher et al., 2019 ;Zhang et al., 2021). ...
... Il semblerait que le type d'exercice puisse impacter différemment la composition corporelle : la course à pied s'avèrerait plus efficace que le vélo(Maillard et al., 2018). Le HIIT présente aussi un intérêt dans l'amélioration des paramètres liés au contrôle glycémique et la sensibilité à l'insuline tels que la glycémie et l'insulinémie à jeun, le score HOMA, le taux d'HbA1c, la réponse glycémique à un test de tolérance au glucose ou encore la glycémie postprandiale(François & Little, 2015 ;Jelleyman et al., 2015 ;Cassidy et al., 2017 ;Wormgoor et al., 2018 ;Liu et al., 2019). Parallèlement, le HIIT améliore le profil lipidique en diminuant le cholestérol total, les TG et le LDL dans les mêmes proportions qu'un MICT, avec toutefois un impact sur le HDL supérieur(Wood et al., 2019). ...
Thesis
La prise en charge de l’obésité et/ou du pré-diabète, deux états pathologiques favorisant le développement d’un diabète de type 2 (DT2) et l’apparition de maladies cardiovasculaires, repose majoritairement sur des mesures hygiéno-diététiques incluant l’activité physique et l’alimentation. Dans ce cadre, les objectifs principaux de cette thèse étaient d’étudier les effets de plusieurs modalités d’entrainement -dont l’entrainement intermittent de haute-intensité (HIIT)-, associées ou non avec Totum-63 (T63, Valbiotis®), un mélange à base d’extraits végétaux, sur la perte de masse grasse totale et (intra-)abdominale et sur l’équilibre glycémique. Différentes pistes mécanistiques explicitant ces effets ont également été investiguées et en particulier le rôle du microbiote intestinal. Nos résultats indiquent qu’un programme de HIIT combiné ou non à du renforcement musculaire est une stratégie efficace et sans danger pour favoriser une perte de masse grasse totale et (intra-)abdominale. Par ailleurs, la prise concomitante de T63 lors d’un entrainement HIIT s’est révélée positive pour améliorer l’équilibre glycémique. Nos travaux ont également montré une modulation spécifique du microbiote intestinal en réponse à chacune de ces interventions. En conclusion, nos résultats indiquent que ces prises en charge novatrices pourraient être proposées à des patients à risque pour éviter l’apparition du DT2 ou autres conséquences métaboliques liées au surpoids ou à l’obésité. L’influence directe du microbiote dans ces adaptations restent toutefois à démontrer.
... There has been some previous research examining the independent effects of CSO and HIIT on glycemic control (5,48,49); however, there is no previously published study on the combined effects of CSO and HIIT, in particular in a T2DM model or in patients with T2DM. Therefore, in the present study, the combined effects of CSO and HIIT on glycemic indices, inflammatory and oxidative stress markers in hepatic cells, hepatic triglyceride content, and liver histopathological findings were investigated in male T2DM rats. ...
Article
Full-text available
Objectives: The purpose of this study was to evaluate the independent and combined effects of camelina sativa oil and high-intensity interval training (HIIT) on liver function, and metabolic outcomes in streptozotocin-induced diabetic rats. Methods: Forty male Wistar rats were randomly assigned to five equal groups (8 per group): Normal control (NC), diabetic control (DC), diabetic + camelina sativa oil (300 mg/kg by oral gavage per day; D + CSO), diabetic + HIIT (running on a treadmill 5 days/week for 8 weeks; D + HIIT), diabetic + camelina sativa oil + HIIT (D + CSO + HIIT). Results: In all three intervention groups (D + CSO, D + HIIT, and D + CSO + HIIT) compared to the DC, hepatic TNF-α, MDA, and histopathology markers, decreased and hepatic PGC-1α, and PPAR-γ increased (p < 0.05). However, the effect of D + CSO was greater than D + HIIT alone. Hepatic TG decreased significantly in D + HIIT and D + CSO + HIIT compared to other groups (p < 0.001). Fasting plasma glucose in all three intervention groups (D + CSO, D + HIIT, and D + CSO + HIIT) and HOMA-IR in D + CSO and D + CSO + HIIT were decreased compared to DC (p < 0.001). Only hepatic TAC and fasting plasma insulin remained unaffected in the three diabetic groups (p < 0.001). Overall, D + CSO + HIIT had the largest effect on all outcomes. Conclusions: At the doses and treatment duration used in the current study, combination of CSO and HIIT was beneficial for reducing liver function and metabolic outcomes other than CSO and HIIT alone.
... Still, physical activity delayed peripheral neuropathy progression, reduced neuropathic symptoms (Zilliox andRussell, 2019, Gholami et al., 2018), improved renal function (Cai et al., 2021), cardiorespiratory fitness (Liu et al., 2019b) and carotid intima-media thickness (Magalhães et al., 2019) in individuals with diabetes in clinical trials. ...
Thesis
Full-text available
Diabetes is hallmarked by high blood glucose levels, which cause progressive generalised vascular damage, leading to microvascular and macrovascular complications. Diabetes-related complications cause severe and prolonged morbidity and are a major cause of mortality among people with diabetes. Despite increasing attention to risk factors of type 2 diabetes, existing evidence is scarce or inconclusive regarding vascular complications and research investigating both micro- and macrovascular complications is lacking. This thesis aims to contribute to current knowledge by identifying risk factors – mainly related to lifestyle – of vascular complications, addressing methodological limitations of previous literature and providing comparative data between micro- and macrovascular complications. To address this overall aim, three specific objectives were set. The first was to investigate the effects of diabetes complication burden and lifestyle-related risk factors on the incidence of (further) complications. Studies suggest that diabetes complications are interrelated. However, they have been studied mainly independently of individuals’ complication burden. A five-state time-to-event model was constructed to examine the longitudinal patterns of micro- (kidney disease, neuropathy and retinopathy) and macrovascular complications (myocardial infarction and stroke) and their association with the occurrence of subsequent complications. Applying the same model, the effect of modifiable lifestyle factors, assessed alone and in combination with complication load, on the incidence of diabetes complications was studied. The selected lifestyle factors were body mass index (BMI), waist circumference, smoking status, physical activity, and intake of coffee, red meat, whole grains, and alcohol. Analyses were conducted in a cohort of 1199 participants with incident type 2 diabetes from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam, who were free of vascular complications at diabetes diagnosis. During a median follow-up time of 11.6 years, 96 cases of macrovascular complications (myocardial infarction and stroke) and 383 microvascular complications (kidney disease, neuropathy and retinopathy) were identified. In multivariable-adjusted models, the occurrence of a microvascular complication was associated with a higher incidence of further micro- (Hazard ratio [HR] 1.90; 95% Confidence interval [CI] 0.90, 3.98) and macrovascular complications (HR 4.72; 95% CI 1.25, 17.68), compared with persons without a complication burden. In addition, participants who developed a macrovascular event had a twofold higher risk of future microvascular complications (HR 2.26; 95% CI 1.05, 4.86). The models were adjusted for age, sex, state duration, education, lifestyle, glucose-lowering medication, and pre-existing conditions of hypertension and dyslipidaemia. Smoking was positively associated with macrovascular disease, while an inverse association was observed with higher coffee intake. Whole grain and alcohol intake were inversely associated with microvascular complications, and a U-shaped association was observed for red meat intake. BMI and waist circumference were positively associated with microvascular events. The associations between lifestyle factors and incidence of complications were not modified by concurrent complication burden, except for red meat intake and smoking status, where the associations were attenuated among individuals with a previous complication. The second objective was to perform an in-depth investigation of the association between BMI and BMI change and risk of micro- and macrovascular complications. There is an ongoing debate on the association between obesity and risk of macrovascular and microvascular outcomes in type 2 diabetes, with studies suggesting a protective effect among people with overweight or obesity. These findings, however, might be limited due to suboptimal control for smoking, pre-existing chronic disease, or short-follow-up. After additional exclusion of persons with cancer history at diabetes onset, the associations between pre-diagnosis BMI and relative annual change between pre- and post-diagnosis BMI and incidence of complications were evaluated in multivariable-adjusted Cox models. The analyses were adjusted for age, sex, education, smoking status and duration, physical activity, alcohol consumption, adherence to the Mediterranean diet, and family history of diabetes and cardiovascular disease (CVD). Among 1083 EPIC-Potsdam participants, 85 macrovascular and 347 microvascular complications were identified during a median follow-up period of 10.8 years. Higher pre-diagnosis BMI was associated with an increased risk of total microvascular complications (HR per 5 kg/m2 1.21; 95% CI 1.07, 1.36), kidney disease (HR 1.39; 95% CI 1.21, 1.60) and neuropathy (HR 1.12; 95% CI 0.96, 1.31); but no association was observed for macrovascular complications (HR 1.05; 95% CI 0.81, 1.36). Effect modification was not evident by sex, smoking status, or age groups. In analyses according to BMI change categories, BMI loss of more than 1% indicated a decreased risk of total microvascular complications (HR 0.62; 95% CI 0.47, 0.80), kidney disease (HR 0.57; 95% CI 0.40, 0.81) and neuropathy (HR 0.73; 95% CI 0.52, 1.03), compared with participants with a stable BMI. No clear association was observed for macrovascular complications (HR 1.04; 95% CI 0.62, 1.74). The impact of BMI gain on diabetes-related vascular disease was less evident. Associations were consistent across strata of age, sex, pre-diagnosis BMI, or medication but appeared stronger among never-smokers than current or former smokers. The last objective was to evaluate whether individuals with a high-risk profile for diabetes and cardiovascular disease (CVD) also have a greater risk of complications. Within the EPIC-Potsdam study, two accurate prognostic tools were developed, the German Diabetes Risk Score (GDRS) and the CVD Risk Score (CVDRS), which predict the 5-year type 2 diabetes risk and 10-year CVD risk, respectively. Both scores provide a non-clinical and clinical version. Components of the risk scores include age, sex, waist circumference, prevalence of hypertension, family history of diabetes or CVD, lifestyle factors, and clinical factors (only in clinical versions). The association of the risk scores with diabetes complications and their discriminatory performance for complications were assessed. In crude Cox models, both versions of GDRS and CVDRS were positively associated with macrovascular complications and total microvascular complications, kidney disease and neuropathy. Higher GDRS was also associated with an elevated risk of retinopathy. The discrimination of the scores (clinical and non-clinical) was poor for all complications, with the C-index ranging from 0.58 to 0.66 for macrovascular complications and from 0.60 to 0.62 for microvascular complications. In conclusion, this work illustrates that the risk of complication development among individuals with type 2 diabetes is related to the existing complication load, and attention should be given to regular monitoring for future complications. It underlines the importance of weight management and adherence to healthy lifestyle behaviours, including high intake of whole grains, moderation in red meat and alcohol consumption and avoidance of smoking to prevent major diabetes-associated complications, regardless of complication burden. Risk scores predictive for type 2 diabetes and CVD were related to elevated risks of complications. By optimising several lifestyle and clinical factors, the risk score can be improved and may assist in lowering complication risk.
... Ramos [11] et al found that only HIIT reduced insulin levels in non-T2DM patients with metabolic syndrome, but not in fasting plasma proinsulin levels in T2DM patients before intervention. A recent systemtic review also found that there were no significant differences in the HIIT group in total cholesterol (TC) and HDL cholesterol (HDL-C), fat mass(FM), waist circumference, and hemoglobin A1c (HbA1c) [12] . In summary, It is still controversial whether HIIT intervention can improve body composition, insulin sensitivity, and HbA1c in T2DM patients compared with MICT. ...
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Background: Diabetes mellitus(DM) has become the third chronic noncommunicable disease worldwide, and is one of the most common chronic diseases in almost all countries. Type 2 diabetes(T2DM) is the most common group of DM, accounting for more than 90% of the DM population. Objectives: This systematic review is conducted to compare the impact of HIIT and MICT on body composition and glucose control in T2DM, and to determine the suitable intervention for HIIT and the more effective forms of HIIT on T2DM. Methods: Seven databases were searched from their inception to 21 November 2022 for randomized controlled trial(RCT) with HIIT and MICT intervention. The effect size was completed by using standardized mean difference (SMD) and standard deviation. Body mass(BM), body mass index (BMI), percent fat mass (PFM), fat mass (FM), fat-free mass (FFM), VO2peak, HbA1c, fasting plasma glucose(FPG), and fasting plasma insulin(FPI) were included in the meta-analysis as outcomes. Results: 15 RCTs with 371 T2DM were conducted in accordance with our inclusion criteria. The results of the meta-analysis revealed that compared to MICT, HIIT had significant effects on VO2peak(SMD=0.4, 95%CI: 0.08 to 0.73, p=0.02) and HbA1c(SMD=-0.24, 95%CI: -0.48 to -0.01, p=0.04), while there were no significant differences in body composition, FPG, and FPI. Conclusion: HIIT provides similar or more benefits on body composition, cardiorespiratory fitness(CRF), and glucose control relative to MICT, which might be influenced by duration, frequency, and HIIT interval. For people with T2DM, HIIT can achieve more improvement in CRF and glucose control than MICT and appear to be more time-saving.
... Traditionally, performing at least 150 min/week of moderate (MICT) to vigorous intensity continuous training distributed at a minimum of three non-consecutive day during the week has been recommended to manage T2DM (6). However, there is evidence that high-intensity interval training (HIIT) might provide superior benefits on a variety of cardiometabolic risk factors in comparison to MICT (7,8), leading physical activity guidelines to suggested the use of HIIT for managing T2DM (9). ...
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Objective To compare the effects of different aerobic training protocols on cardiometabolic variables in patients with type 2 diabetes mellitus (T2DM). Methods This study was a parallel clinical trial. Fifty-two men and women with T2DM (>40 years) were randomly allocated into three groups, and 44 (22 males/22 females) were included in the final analysis. Exercise intensity was based on the speed corresponding to the maximum oxygen consumption (v V ˙ O 2 max). Moderate intensity continuous training (MICT) involved 14 minutes at 70% of v V ˙ O 2 max; short interval high-intensity interval training (S-HIIT) consisted of 20 bouts of 30 seconds at 100% of V ˙O 2 max with 30 seconds passive recovery; long interval high-intensity training (L-HIIT) consisted of 5 bouts of 2 minutes at 100% of v V ˙ O 2 max with 2 minutes passive recovery. Training protocols were performed on a motorized treadmill two times per week for eight weeks. Glycated hemoglobin (Hb1Ac), total cholesterol, triglycerides, resting systolic blood pressure (SBP), resting diastolic blood pressure (DBP), resting heart rate (resting HR) and maximum oxygen consumption ( V ˙O 2 max) were measured before and after the exercise intervention. The study was registered on the Brazilian clinical trial records (ID: RBR45 4RJGC3). Results There was a significant difference between groups for changes on V ˙ O 2 max. Greater increases on V ˙ O 2 max were achieved for L-HIIT (p = 0.04) and S-HIIT (p = 0.01) in comparison to MICT group, with no significant difference between L-HIIT and S-HIIT (p = 0.9). Regarding comparison within groups, there were significant reductions on HbA1c and triglycerides levels only for L-HIIT (p< 0.05). V ˙ O 2 max significantly increased for both L-HIIT (MD = 3.2 ± 1.7 ml/kg/min, p< 0.001) and S-HIIT (MD = 3.4 ± 1.7, p< 0.001). There was a significant reduction on resting SBP for L-HIIT group (MD = -12.07 ± 15.3 mmHg, p< 0.01), but not for S-HIIT and MICT. There were no significant changes from pre- to post-training on fasting glycemia, total cholesterol, HDL, LDL, resting HR and resting DBP for any group (p > 0.05). Conclusion Low-volume HIIT promoted greater improvements in cardiorespiratory capacity in comparison with low-volume MICT, independent of the protocols used. There were no other differences between groups. All protocols improved at least one of the variables analyzed; however, the most evident benefits were after the high-intensity protocols, especially L-HIIT.
... A meta-analysis by Liu et al. [17] investigated the impact of high-intensity interval training (HIIT) compared to moderate-intensity continuous training (MICT) on health variables in patients with type 2 diabetes. In comparison, HIIT resulted in a more effective increase in maximal oxygen uptake (VO 2peak ), and improvements in HbA1c levels and lipid profile (LDL cholesterol). ...
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Combining regular exercise and a healthy diet is recommended in international guidelines to fight type 2 diabetes mellitus (T2DM). Low- and very low-carbohydrate diets have attracted attention in the last years. This article takes a critical look at the possible effects when regular exercise and carbohydrate restriction are combined. An increased intervention effect on the oxidative capacity as well as glucose and lipid profiles can be assumed (at least for a short period of time). However, anabolic signaling pathways might be blunted during a very low-carbohydrate diet and increasing ketosis. Thus, muscle build-up can become difficult or impossible. Furthermore, maximal performance during high-intensity workouts may be attenuated due to a possible reduced anaerobic glycolysis and metabolic inflexibility in T2DM patients. However, more studies are needed to evaluate the effects of this combination in comparison to those of exercise and other types of diet.
Article
Background: Physical activity may be effective in alleviating depressive symptoms and improving glycaemic control; however, evidence to guide practice is limited. The current review was conducted to assess the effects of physical activity on depression and glycaemic control in people with type 2 diabetes mellitus. Methods: Randomized controlled clinical trials, from the earliest record to October 2021, which recruited adults with the diagnosis of type 2 diabetes mellitus and compared physical activity with no interventions or usual care for the management of depression were included. The outcomes were change in depression severity and glycaemic control. Results: In 17 trials, including 1362 participants, physical activity was effective in reducing the severity of depressive symptoms (SMD = -057; 95%CI = -0.80, -0.34). However, physical activity did not have a significant effect in improving markers of glycaemic control (SMD = -0.18; 95%CI = -0.46, 0.10). Limitations: There was substantial heterogeneity in the included studies. Furthermore, risk of bias assessment showed that most of the included studies were of low quality. Conclusions: Physical activity can effectively reduce the severity of depressive symptoms, nonetheless, it appears that physical activity is not significantly effective in improving glycaemic control in adults who have both type 2 diabetes mellitus and depressive symptoms. The latter finding is surprising, however, given the limited evidence on which this is based, future research on the effectiveness of physical activity for depression in this population should include high quality trials with glycaemic control as an outcome.
Article
The aim of this study was to compare the effect of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) with equal energy expenditure on glycemic and cardiometabolic risk factors in people with Type 2 Diabetes Mellitus (T2DM) when compared to the control. Sixty-three people with T2DM were randomly assigned to HIIT, MICT, or non-exercising controls. Individuals were trained with HIIT at 90 and 30% of their VO2peak (1:2 min ratio) starting from 8 up to 16 intervals and MICT at 50% of VO2peak, on a cycle ergometer, 3 times/week for 12 weeks under supervision. The primary outcome measure was the change in HbA1c. Aerobic capacity, cardiovascular responses, anthropometric measures, body composition, glycemic, and cardiometabolic risk factors were measured at the beginning and the end of the 12-week training period. There was no significant difference between HIIT and MICT or when compared to the control for HbA1c, glucose, insulin resistance, blood lipids, cardiovascular responses, anthropometric measures, body composition, and abdominal and visceral fat (padj>0.05). HIIT and MICT increased VO2peak significantly compared to controls (p<0.05) but not to each other (p>0.05). Both HIIT and MICT improved VO2peak and HbA1c after 12 weeks of training compared to their baseline, furthermore, only MICT caused additional improvements in cardiovascular responses, anthropometric measures, and abdominal fat compared to baseline (p<0.05). As a conclusion, isoenergetic HIIT or MICT did not improve HbA1c. The two protocols were equally efficient for improvement in aerobic capacity but had little effect on other cardiometabolic factors. Trial registration: ClinicalTrials.gov identifier: NCT03682445.
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Introduction Regular physical activity (PA) can reduce the risk of developing type 2 diabetes, but adherence to time-orientated (150 min week⁻¹ or more) PA guidelines is very poor. A practical and time-efficient PA regime that was equally efficacious at controlling risk factors for cardio-metabolic disease is one solution to this problem. Herein, we evaluate a new time-efficient and genuinely practical high-intensity interval training (HIT) protocol in men and women with pre-existing risk factors for type 2 diabetes. Materials and methods One hundred eighty-nine sedentary women (n = 101) and men (n = 88) with impaired glucose tolerance and/or a body mass index >27 kg m⁻² [mean (range) age: 36 (18–53) years] participated in this multi-center study. Each completed a fully supervised 6-week HIT protocol at work-loads equivalent to ~100 or ~125% V˙O2 max. Change in V˙O2 max was used to monitor protocol efficacy, while Actiheart™ monitors were used to determine PA during four, weeklong, periods. Mean arterial (blood) pressure (MAP) and fasting insulin resistance [homeostatic model assessment (HOMA)-IR] represent key health biomarker outcomes. Results The higher intensity bouts (~125% V˙O2 max) used during a 5-by-1 min HIT protocol resulted in a robust increase in V˙O2 max (136 participants, +10.0%, p < 0.001; large size effect). 5-by-1 HIT reduced MAP (~3%; p < 0.001) and HOMA-IR (~16%; p < 0.01). Physiological responses were similar in men and women while a sizeable proportion of the training-induced changes in V˙O2 max, MAP, and HOMA-IR was retained 3 weeks after cessation of training. The supervised HIT sessions accounted for the entire quantifiable increase in PA, and this equated to 400 metabolic equivalent (MET) min week⁻¹. Meta-analysis indicated that 5-by-1 HIT matched the efficacy and variability of a time-consuming 30-week PA program on V˙O2 max, MAP, and HOMA-IR. Conclusion With a total time-commitment of <15 min per session and reliance on a practical ergometer protocol, 5-by-1 HIT offers a new solution to modulate cardio-metabolic risk factors in adults with pre-existing risk factors for type 2 diabetes while approximately meeting the MET min week⁻¹ PA guidelines. Long-term randomized controlled studies will be required to quantify the ability for 5-by-1 HIT to reduce the incidence of type 2 diabetes, while strategies are required to harmonize the adaptations to exercise across individuals.
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Background Exercise is an effective strategy for reducing total and cardiovascular mortality in patients with coronary artery disease. However, it is not clear which modality is best. We performed a meta-analysis to investigate the effects of high-intensity interval versus moderate-intensity continuous training of coronary artery disease patients. Methods We searched MEDLINE, PEDro, LILACS, SciELO and the Cochrane Library (from the earliest date available to November 2016) for controlled trials that evaluated the effects of high-intensity interval versus moderate-intensity continuous training for coronary artery disease patients. Weighted mean differences and 95% confidence intervals were calculated, and heterogeneity was assessed using the I(2) test. Results Twelve studies met the study criteria, including 609 patients. High-intensity interval training resulted in improvement in peak oxygen uptake weighted mean difference (1.3 ml/kg/min, 95% confidence interval: 0.6-1.9, n = 594) compared with moderate-intensity continuous training. No significant difference in physical, emotional, and social domain of quality of life was found for participants for participants in the high-intensity interval training group compared with the moderate-intensity continuous training group. Sub-analysis of three studies with isocaloric exercise training showed no significant difference in peak oxygen uptake weighted mean difference (0.4 ml/kg/min, 95% confidence interval: -0.1-0.9, n = 137) for participants in the high-intensity interval training group compared with moderate-intensity continuous training group. Conclusions High-intensity interval training may improve peak oxygen uptake and should be considered as a component of care of coronary artery disease patients. However, this superiority disappeared when isocaloric protocol is compared.
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Background We investigated the influence of aerobic capacity on the improvement in glycemic control achieved by long-term aerobic exercise in type 2 diabetes. Methods Fifty-three male patients with type 2 diabetes, recruited from outpatient clinics, wore multiple-memory accelerometers and were instructed to exercise at moderate intensity for ≥30 min on ≥3 days per week over 12 months. Peak oxygen uptake (peak \({\dot{\text{V}}\text{O}}_{ 2}\)) and serum glycated albumin (GA) were measured at baseline and after 3, 6, 12 months. Peak \({\dot{\text{V}}\text{O}}_{ 2}\) data were expressed as percentages of predicted values. ResultsAccording to the number of bouts of exercise (intensity, ≥4 METs; duration, ≥15 min), the subjects were divided into inactive (<3 times per week) or active (≥3 times per week) groups. Serum GA decreased significantly after 3, 6, 12 months only in the active group. When the subjects were assigned to four groups according to initial peak \({\dot{\text{V}}\text{O}}_{ 2}\) (%pred) (low-fitness or high-fitness) and the number of bouts of exercise (active or inactive), serum GA decreased significantly after 3, 6, 12 months only in the high-fitness/active group. When the subjects were also assigned to four groups according to the change in peak \({\dot{\text{V}}\text{O}}_{ 2}\) (%pred) (improved or unimproved) and the number of bouts of exercise (active or inactive), serum GA decreased significantly after 3 and 12 months only in the improved/active group. Conclusion The improvement in glycemic control achieved by aerobic exercise was associated with both the initial and the increase in peak \({\dot{\text{V}}\text{O}}_{ 2}\) during aerobic exercise.
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Importance It is unclear whether a lifestyle intervention can maintain glycemic control in patients with type 2 diabetes. Objective To test whether an intensive lifestyle intervention results in equivalent glycemic control compared with standard care and, secondarily, leads to a reduction in glucose-lowering medication in participants with type 2 diabetes. Design, Setting, and Participants Randomized, assessor-blinded, single-center study within Region Zealand and the Capital Region of Denmark (April 2015-August 2016). Ninety-eight adult participants with non–insulin-dependent type 2 diabetes who were diagnosed for less than 10 years were included. Participants were randomly assigned (2:1; stratified by sex) to the lifestyle group (n = 64) or the standard care group (n = 34). Interventions All participants received standard care with individual counseling and standardized, blinded, target-driven medical therapy. Additionally, the lifestyle intervention included 5 to 6 weekly aerobic training sessions (duration 30-60 minutes), of which 2 to 3 sessions were combined with resistance training. The lifestyle participants received dietary plans aiming for a body mass index of 25 or less. Participants were followed up for 12 months. Main Outcomes and Measures Primary outcome was change in hemoglobin A1c (HbA1c) from baseline to 12-month follow-up, and equivalence was prespecified by a CI margin of ±0.4% based on the intention-to-treat population. Superiority analysis was performed on the secondary outcome reductions in glucose-lowering medication. Results Among 98 randomized participants (mean age, 54.6 years [SD, 8.9]; women, 47 [48%]; mean baseline HbA1c, 6.7%), 93 participants completed the trial. From baseline to 12-month follow-up, the mean HbA1c level changed from 6.65% to 6.34% in the lifestyle group and from 6.74% to 6.66% in the standard care group (mean between-group difference in change of −0.26% [95% CI, −0.52% to −0.01%]), not meeting the criteria for equivalence (P = .15). Reduction in glucose-lowering medications occurred in 47 participants (73.5%) in the lifestyle group and 9 participants (26.4%) in the standard care group (difference, 47.1 percentage points [95% CI, 28.6-65.3]). There were 32 adverse events (most commonly musculoskeletal pain or discomfort and mild hypoglycemia) in the lifestyle group and 5 in the standard care group. Conclusions and Relevance Among adults with type 2 diabetes diagnosed for less than 10 years, a lifestyle intervention compared with standard care resulted in a change in glycemic control that did not reach the criterion for equivalence, but was in a direction consistent with benefit. Further research is needed to assess superiority, as well as generalizability and durability of findings. Trial Registration clinicaltrials.gov Identifier: NCT02417012
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AimsTo establish if aerobic exercise training is associated with beneficial effects on clinical outcomes and glycaemic profile in people with type II diabetes. MethodsA systematic search was conducted to identify studies through a search of MEDLINE (1985 to Sept 1, 2016, Cochrane Controlled Trials Registry (1966 to Sept 1, 2016), CINAHL, SPORTDiscus and Science Citation Index. The search strategy included a mix of MeSH and free text terms for related key concepts. Searches were limited to prospective randomized or controlled trials of aerobic exercise training in humans with type II diabetes, aged >18 years, lasting >2 weeks. ResultsOur analysis included 27 studies (38 intervention groups) totalling 1372 participants, 737 exercise and 635 from control groups. The studies contain data from 39,435 patient-hours of exercise training. Our analyses showed improvements with exercise in glycosylated haemoglobin (HbA1C%) MD: −0.71%, 95% CI −1.11, −0.31; p value = 0.0005. There were significant moderator effects; for every additional week of exercise HbA1C% reduces between 0.009 and 0.04%, p = 0.002. For those exercising at vigorous intensity peak oxygen consumption (peak VO2) increased a further 0.64 and 5.98 ml/kg/min compared to those doing low or moderate intensity activity. Homeostatic model assessment of insulin resistance (HOMA-IR) was also improved with exercise MD: −1.02, 95% CI −1.77, −0.28; p value = 0.007; as was fasting serum glucose MD: −12.53 mmol/l, 95% CI −18.94, −6.23; p value <0.0001; and serum MD: −10.39 IU, 95% CI −17.25, −3.53; p value = 0.003. Conclusions Our analysis support existing guidelines that for those who can tolerate it, exercise at higher intensity may offer superior fitness benefits and longer program duration will optimize reductions in HbA1C%.
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Purpose . The aim of this study was to compare the effects of high-intensity interval training (INTERVAL) and moderate-intensity continuous training (CONTINUOUS) on aerobic capacity in cardiac patients. Methods . A meta-analysis identified by searching the PubMed, Cochrane Library, EMBASE, and Web of Science databases from inception through December 2016 compared the effects of INTERVAL and CONTINUOUS among cardiac patients. Results . Twenty-one studies involving 736 participants with cardiac diseases were included. Compared with CONTINUOUS, INTERVAL was associated with greater improvement in peak VO 2 (mean difference 1.76 mL/kg/min, 95% confidence interval 1.06 to 2.46 mL/kg/min, p<0.001 ) and VO 2 at AT (mean difference 0.90 mL/kg/min, 95% confidence interval 0.0 to 1.72 mL/kg/min, p=0.03 ). No significant difference between the INTERVAL and CONTINUOUS groups was observed in terms of peak heart rate, peak minute ventilation, VE/VCO 2 slope and respiratory exchange ratio, body mass, systolic or diastolic blood pressure, triglyceride or low- or high-density lipoprotein cholesterol level, flow-mediated dilation, or left ventricular ejection fraction. Conclusions . This study showed that INTERVAL improves aerobic capacity more effectively than does CONTINUOUS in cardiac patients. Further studies with larger samples are needed to confirm our observations.
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PurposeIt remains to be established how high-intensity aerobic interval training (HAIT) affects risk factors associated with type 2 diabetes (TD2). This study investigated effects of HAIT on maximal oxygen uptake (VO2max), glycated Hemoglobin type A1C (HbA1c), insulin resistance (IR), fat oxidation (FatOx), body weight (BW), percent body fat (%BF), lactate threshold (LT), blood pressure (BP), and blood lipid profile (BLP) among persons with T2D. Results were compared to the effects after a moderate-intensity training (MIT) program. Methods Thirty-eight individuals with T2D completed 12 weeks of supervised training. HAIT consisted of 4 × 4 min of walking or running uphill at 85–95% of maximal heart rate, and MIT consisted of continuous walking at 70–75% of maximal heart rate. ResultsA 21% increase in VO2max (from 25.6 to 30.9 ml kg−1 min−1, p < 0.001), and a reduction in HbA1c by −0.58% points (from 7.78 to 7.20%, p < 0.001) was found in HAIT. BW and body mass index (BMI) was reduced by 1.9% (p < 0.01). There was a tendency towards an improved FatOx at 60% VO2max (14%, p = 0.065). These improvements were significant different from MIT. Both HAIT and MIT increased velocity at LT, and reduced %BF, waist circumference, hip circumference, and BP, with no significant differences between the two groups. Correlations were found between change in VO2max and change in HbA1c when the two intervention groups were combined (R = −0.52, p < 0.01). ConclusionHAIT is an effective exercise strategy to improve aerobic fitness and reduce risk factors associated with T2D.
Article
AIM To evaluate if high-intensity interval training (HIIT) with a lower time commitment can be equally effective as endurance training (END) on glycemic control, physical fitness and body composition in individuals with type 2 diabetes. MATERIALS AND METHODS Twenty-nine individuals with type 2 diabetes were allocated to control (CON; no training), END, or HIIT. Training groups were prescribed three training sessions per week consisting of either 40 min cycling at 50% of peak workload (END) or ten 1 min intervals at 95% of peak workload interspersed by 1 min active recovery (HIIT). Glycemic control (HbA1c, oral glucose tolerance test, 3-hours mixed meal tolerance test with double tracer technique, and continuous glucose monitoring (CGM)), lipolysis, VO2peak and body composition were evaluated before and after 11 weeks of intervention. RESULTS Exercise training increased VO2peak more in HIIT (20±20%) compared with END (8±9%) despite lower total energy expenditure and time usage during the training sessions. HIIT decreased whole body and android fat mass compared with CON. In addition, visceral fat mass, HbA1c, fasting glucose, postprandial glucose, glycemic variability and HOMA-IR decreased after HIIT. The reduced postprandial glucose in HIIT was primarily driven by a lower rate of exogenous glucose appearance. In CON, postprandial lipolysis was augmented over the 11 week control period. CONCLUSIONS Despite a ~45% lower training volume, HIIT resulted in similar or even better improvements in physical fitness, body composition and glycemic control compared to END. HIIT therefore appears to be an important time-efficient treatment for individuals with type 2 diabetes.
Article
AimsA systematic review was conducted of randomized trials which evaluated the impact of physical activity on the change in fasting glucose and HbA1c. MethodsA literature search was conducted in PubMed until December 2015. Studies reporting glucose or HbA1c at baseline and at the end of study were included, and the change and its variance were estimated from studies with complete data. Mixed-effect random models were used to estimate the change of fasting glucose (mg/dl) and HbA1c (%) per additional minutes of physical activity per week. ResultsA total of 125 studies were included in the meta-analysis. Based on 105 studies, an increase of 100 min in physical activity per week was associated with an average change of −2.75 mg/dl of fasting glucose (95% CI −3.96; −1.55), although there was a high degree of heterogeneity (83.5%). When restricting the analysis on type 2 diabetes and prediabetes subjects (56 studies), the average change in fasting glucose was −4.71 mg/dl (95% CI −7.42; −2.01). For HbA1c, among 76 studies included, an increase of 100 min in physical activity per week was associated with an average change of −0.14% of HbA1c (95% CI −0.18; −0.09) with heterogeneity (73%). A large degree of publication bias was identified (Egger test p < 0.001). When restricting the analysis on type 2 diabetes and prediabetes subjects (60 studies), the average change in HbA1c was −0.16% (95% CI −0.21; −0.11). Conclusions This analysis demonstrates that moderate increases in physical activity are associated with significant reductions in both fasting glucose and HbA1c.
Article
Background Arterial stiffness (AS) and baroreflex sensitivity (BRS) are subclinical markers of vascular diseases in type 2 diabetes (T2D). We evaluated the effects of aerobic interval training (AIT), with loads prescribed according to individual heart rate and lactate profiling obtained during a baseline treadmill test (TRIMPi method), on AS and BRS in patients with early-onset T2D without cardiovascular complications. Population study and methods Twenty-two sedentary overweight T2D patients (aged 57 ± 7 years) were randomized to 12-weeks open-label of supervised AIT by TRIMPi (n = 8) or unsupervised physical activity as per usual care (SOC) (n = 11). Following parameters were evaluated (pre- and post-): anthropometrics; six-minute walking test (6MWT); fasting glucose, insulin, HbA1c; Pulse Wave Velocity (PWV) and Augmentation Index (AIxHR75) using radial approach (SphigmoCor System); BRS using Finapress method. Results Both interventions significantly improved distance walked during 6MWT (AIT 52 ± 21 m; SOC 39 ± 24 m, p < 0.001 for both). PWV significantly improved with AIT (p < 0.001) whereas did not vary with SOC (p = 0.47). Similar trend was observed for AIxHR75. Resulting percent changes from baseline were significantly better for AIT vs SOC, in both PWV (−15.8 ± 2.1 vs +1.50 ± 3.4%, p < 0.001) and AIxHR75 (−28.9 ± 3.2% vs +12.7 ± 2.4%, p < 0.001). BRS similarly improved in both groups (p < 0.001 for both), as well as body weight, HbA1c and blood pressure. Conclusion In sedentary T2D patients, 12-weeks AIT individualized by TRIMPi method improved AS to a greater extent than usual recommendation on physical activity, whilst exerting comparable effects on exercise capacity, glycemic control and body weight. Further researches are needed to ascertain durability of these effects.