ArticlePDF AvailableLiterature Review

Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials

Authors:

Abstract

Background Enhancing cardiovascular fitness can lead to substantial health benefits. High-intensity interval training (HIT) is an efficient way to develop cardiovascular fitness, yet comparisons between this type of training with traditional endurance training are equivocal. Objective Our objective was to meta-analyse the effects of endurance training and HIT on the maximal oxygen consumption (VO2max) of healthy, young to middle-aged adults. Methods Six electronic databases were searched (MEDLINE, PubMed, SPORTDiscus, Web of Science, CINAHL and Google Scholar) for original research articles. A search was conducted and search terms included ‘high intensity’, ‘HIT’, ‘sprint interval training’, ‘endurance training’, ‘peak oxygen uptake’, ‘VO2max’. Inclusion criteria were controlled trials, healthy adults aged 18-45 y, training duration ≥2 weeks, VO2max assessed pre- and post-training. Twenty-eight studies met the inclusion criteria and were included in the meta-analysis. This resulted in 723 participants with a mean ± SD age and initial fitness of 25.1 ± 5 y and 40.8 ± 7.9 mL•kg-1•min-1, respectively. We made probabilistic magnitude-based inferences for meta-analysed effects based on standardized thresholds for small, moderate and large changes (0.2, 0.6 and 1.2, respectively) derived from between-subject standard deviations (SDs) for baseline VO2max. Results The meta-analysed effect of endurance training on VO2max was a possibly large beneficial effect (4.9 mL•kg-1•min-1; 95% confidence limits ±1.4 mL•kg-1•min-1), when compared with no exercise controls. A possibly moderate additional increase was observed for typically younger subjects (2.4 mL•kg-1•min-1; ±2.1 mL•kg-1•min-1) and interventions of longer duration (2.2 mL•kg-1•min-1; ±3.0 mL•kg-1•min-1), and a small additional improvement for subjects with lower baseline fitness (1.4 mL•kg-1•min-1; ±2.0 mL•kg-1•min-1). When compared to no exercise controls, there was likely large beneficial effect of HIT (5.5 mL•kg-1•min-1; ±1.2 mL•kg-1•min-1), with a likely moderate greater additional increase for subjects with lower baseline fitness (3.2 mL•kg-1•min-1; ±1.9 mL•kg-1•min-1) and interventions of longer duration (3.0 mL•kg-1•min-1; ±1.9 mL•kg-1•min-1), and a small lesser effect for typically longer HIT repetitions (-1.8 mL•kg-1•min-1; ±2.7 mL•kg-1•min-1). The modifying effects of age (0.8 mL•kg-1•min-1; ±2.1 mL•kg-1•min-1) and work:rest ratio (0.5 mL•kg-1•min-1; ±1.6 mL•kg-1•min-1) were unclear. When compared to endurance training, there was a possibly small beneficial effect for HIT (1.2 mL•kg-1•min-1; ±0.9 mL•kg-1•min-1) with small additional improvements for typically longer HIT repetitions (2.2 mL•kg-1•min-1; ±2.1 mL•kg-1•min-1), older subjects (1.8 mL•kg-1•min-1; ±1.7 mL•kg-1•min-1), interventions of longer duration (1.7 mL•kg-1•min-1; ±1.7 mL•kg-1•min-1), greater work:rest ratio (1.6 mL•kg-1•min-1; ±1.5 mL•kg-1•min-1) and lower baseline fitness (0.8 mL•kg-1•min-1; ±1.3 mL•kg-1•min-1). Conclusion Endurance training and HIT both elicit large improvements in the VO2max of healthy, young to middle-aged adults with the gains in VO2max being greater following HIT, when compared to endurance training.
SYSTEMATIC REVIEW
Effectiveness of High-Intensity Interval Training (HIT)
and Continuous Endurance Training for VO
2max
Improvements:
A Systematic Review and Meta-Analysis of Controlled Trials
Zoran Milanovic
´
1
Goran Sporis
ˇ
2
Matthew Weston
3
Published online: 5 August 2015
Ó Springer International Publishing Switzerland 2015
Abstract
Background Enhancing cardiovascular fitness can lead to
substantial health benefits. High-intensity interval training
(HIT) is an efficient way to develop cardiovascular fitness,
yet comparisons between this type of training and tradi-
tional endurance training are equivocal.
Objective Our objective was to meta-analyse the effects of
endurance training and HIT on the maximal oxygen con-
sumption (VO
2max
) of healthy, young to middle-aged adults.
Methods Six electronic databases were searched (MED-
LINE, PubMed, SPORTDiscus, Web of Science, CINAHL
and Google Scholar) for original research articles. A search
was conducted and search terms included ‘high intensity’,
‘HIT’, ‘sprint interval training’, ‘endurance training’, ‘peak
oxygen uptake’, and ‘VO
2max
’. Inclusion criteria were
controlled trials, healthy adults aged 18–45 years, training
duration C2 weeks, VO
2max
assessed pre- and post-training.
Twenty-eight studies met the inclusion criteria and were
included in the meta-analysis. This resulted in 723 partici-
pants with a mean ± standard deviation (SD) age and initial
fitness of 25.1 ± 5 years and 40.8 ± 7.9 mLkg
-1
min
-1
,
respectively. We made probabilistic magnitude-based
inferences for meta-analysed effects based on standardised
thresholds for small, moderate and large changes (0.2, 0.6
and 1.2, respectively) derived from between-subject SDs for
baseline VO
2max
.
Results The meta-analysed effect of endurance training on
VO
2max
was a possibly large beneficial effect
(4.9 mLkg
-1
min
-1
; 95 % confidence limits
±1.4 mLkg
-1
min
-1
), when compared with no-exercise
controls. A possibly moderate additional increase was
observed for typically younger subjects (2.4 mLkg
-1-
min
-1
; ±2.1 mLkg
-1
min
-1
) and interventions of longer
duration (2.2 mLkg
-1
min
-1
; ±3.0 mLkg
-1
min
-1
), and
a small additional improvement for subjects with lower
baseline fitness (1.4 mLkg
-1
min
-1
; ±2.0 mLkg
-1-
min
-1
). When compared with no-exercise controls, there
was likely a large beneficial effect of HIT (5.5 mLkg
-1-
min
-1
; ±1.2 mLkg
-1
min
-1
), with a likely moderate
greater additional increase for subjects with lower baseline
fitness (3.2 mLkg
-1
min
-1
; ±1.9 mLkg
-1
min
-1
) and
interventions of longer duration (3.0 mLkg
-1
min
-1
;
±1.9 mLkg
-1
min
-1
), and a small lesser effect for typi-
cally longer HIT repetitions (-1.8 mLkg
-1
min
-1
;
±2.7 mLkg
-1
min
-1
). The modifying effects of age
(0.8 mLkg
-1
min
-1
; ±2.1 mLkg
-1
min
-1
) and work/rest
ratio (0.5 mLkg
-1
min
-1
; ±1.6 mLkg
-1
min
-1
)were
unclear. When compared with endurance training, there was
a possibly small beneficial effect for HIT (1.2 mLkg
-1-
min
-1
; ±0.9 mLkg
-1
min
-1
) with small additional
improvements for typically longer HIT repetitions
(2.2 mLkg
-1
min
-1
; ±2.1 mLkg
-1
min
-1
), older subjects
(1.8 mLkg
-1
min
-1
; ±1.7 mLkg
-1
min
-1
), interventions
of longer duration (1.7 mLkg
-1
min
-1
; ±1.7 mLkg
-1-
min
-1
), greater work/rest ratio (1.6 mLkg
-1
min
-1
;
±1.5 mLkg
-1
min
-1
) and lower baseline fitness
(0.8 mLkg
-1
min
-1
; ±1.3 mLkg
-1
min
-1
).
Conclusion Endurance training and HIT both elicit large
improvements in the VO
2max
of healthy, young to middle-
& Zoran Milanovic
´
zoooro_85@yahoo.com
1
Faculty of Sport and Physical Education, University of Nis,
C
ˇ
arnojevic
´
eva 10a, 18000 Nis, Serbia
2
Faculty of Kinesiology, University of Zagreb, Zagreb,
Croatia
3
Department of Sport and Exercise Sciences, School of Social
Sciences, Business and Law, Teesside University,
Middlesbrough, UK
123
Sports Med (2015) 45:1469–1481
DOI 10.1007/s40279-015-0365-0
aged adults, with the gains in VO
2max
being greater fol-
lowing HI T when compared with endurance training.
Key Points
When compared with no exercise, endurance training
and high-intensity interval training elicit large
improvements in maximal oxygen uptake.
Endurance training and high-intensity interval
training elicit additional benefit for individuals with
lower pre-training fitness.
In healthy, young to middle-aged adults, high-
intensity interval training improves maximal oxygen
uptake to a greater extent than traditional endurance
training.
1 Introduction
Improving or maintaining cardiovascular fitness can
reduce the risk of all-cause and cardiovascular diseases
[1]. Indeed, when com pared with o ther well established
risk factors such as hypertension, diabetes mellitus,
smoking and obe sity, cardiovascular fitness is a more
powerful predictor of mortality [2, 3]. Fitnes s training
programme s aimed at the improvement of cardiovascular
fitness therefore have broad appeal to the general
population.
The fitness industry has recently seen a surge of interest
in high-intensity interval training (HIT)—a burst-and-re-
cover cycle that is suggested to be a viable alternative to
the traditional approach to enhancing aerobic fitness,
namely continuous endurance training [4]. However,
specifying an optimal training regimen for im proving fit-
ness in the general community requires knowledge of how
these different types of training influence adaptations in
physiological parameters [5]. Consequently, there has been
a substantial amount of research examining which modality
of training, endurance or HIT, is superior for aerobic fitness
improvements.
Endurance training and HIT both increase aerobic fit-
ness [6] and thus relate to benefits in cardiovascular risk
factors, fitness and all-cause mortality [7]. Some studies,
however, have suggested that HIT leads to improvements
in both aerobic and anaerobic fitness [8] and improves
endurance performance to a greater extent than endurance
training alone [9]. For example, Daussin et al. [10] found
that maximal oxygen uptake (VO
2max
) increases were
higher for untrained men and women who participated in
an 8-week HIT program me (15 %) than they were for
untrained participants undertaking an endurance training
programme (9 %). High-intensity interval training has also
been reported to be more effective than continuous, steady-
state exercise training for inducing fat loss in men and
women, despite requiring considerably less total energy
expenditure during training [11, 12]. Recent studies have
demonstrated that the cardiovascular adaptations occurring
following HIT are similar, and in some cases superior, to
those following endurance training [5, 13], and further
beneficial effects of HIT were provided by the Nord-
Trøndelag Health Study [13], which indicated that just a
single weekly bout of HIT reduced the risk of cardiovas-
cular disease in both men and women (relative risk: 0.61
and 0.49, respectively).
It is therefore not surprising that recent meta-analyses
[1417] have confirmed HIT to be an appropriate training
stimulus to improve cardiorespiratory fitness and reduce
metabolic risk factors in patient populations. Using similar
inclusion criteri a to the aforementioned reviews, Bacon
et al. [18] meta-analysed the effect of HIT on VO
2max
but
only calculated an overall effect size, irrespective of the
type of control group (no-exercise or endurance training).
Consequently, we cannot conclude that HIT is better than
endurance training because the effect of HIT is, naturally,
much higher in comparison with no-exercise control groups
than the effect when compared with endurance training
controls. A separate analysis (HIT vs endurance training;
HIT vs no exercise) is therefore necessary to determine
more precise effects of HIT. Gist et al. [19] reported a
moderate effect (0.69) of sprint interval training (SIT)—
classified as a form of HIT at the highest end of the
intensity spectrum [20]—on VO
2max
in comparison with
no-exercise control groups; yet a trivial effect (0.04) when
compared with endurance training controls. However, this
meta-analysis [19], as well as the recent meta-analyses
performed by Weston et al. [21] and Sloth et al. [20], only
addressed the effect of SIT on VO
2max
. In doing so, these
reviews excluded HIT research utilizing longer interval
durations and shorter recovery periods. While there have
been meta-analyses on longer duration HIT repetitions in
patient populations [1417], to the best of the authors’
knowledge there is no systematic review and meta-anal ysis
examining the effect of longer duration HIT repetitions in
comparison with either endurance training or no-exercise
controls. Therefore, our aim was to meta-analyse the
effects on VO
2max
of endurance training and HIT in heal-
thy, young to middle-aged adults, when compare d with no-
exercise controls and also when the two types of training
were compared with one another. A further aim was to
examine the modifying effects of study and subject
characteristics.
1470 Z. Milanovic
´
et al.
123
2 Methods
2.1 Search Strategy
Electronic database searches were performed using MED-
LINE, PubMed, SPORTDiscus, Web of Science, CINAHL
and Google Scholar using all available records up to 28
February 2014. The search terms covered the areas of high-
intensity interval training, continuous endurance training
and VO
2max
using a combination of the following key
words: high-intensity interval training, high-intensity
intermittent training, sprint interval training, endurance
training, continuous endurance training, aerobic exercises,
maximal oxygen uptake, peak oxygen uptake, cardiores-
piratory fitness, VO
2max
, young adults. The literature
search, quality assessment and data extraction were con-
ducted independently by two authors (ZM and GS). Papers
that were clearly not relevant were removed from the
database list before assessing all other titles and abstracts
using our pre-determined inclusi on and exclusion criteria.
Inter-reviewer disagreements were resolved by consensus
opinion or arbitration by a third reviewer. Full papers,
including reviews, were then collected and when not
available the corresponding author was contacted by mail.
Reference lists of the selected manuscripts were also
examined for any other potentially eligible papers. This
systematic review and meta-analysis was undertaken in
accordance with the Preferred Reporting Items for Sys-
tematic Reviews and Meta-Analyses (PRISMA) statement
[22].
2.2 Inclusion Criteria
2.2.1 Type of Study
Our meta-analysis included randomised and non-ran-
domised controlled trials, written in English. Uncontrolled
and cross-sectional studies were excluded from analysis
and only studies published in the last 20 years (after 1995)
were included in our review.
2.2.2 Type of Participants
The type of participants included i n our meta-analysis
were healthy, untrained, sedentary, recreational and non-
athleticmenandwomenagedbetween18and45years,
who were not suffering from any kind of acute or chronic
diseases. No exclusion criteri a w ere applied to partici-
pant baseline fitness; however, studies with overweight
and o bese participants were excluded from our re view
due to confusion over the proper expression of VO
2max
data when comparing obese and normal weight
individuals.
2.2.3 Type of Interventions
To be included in our meta-analysis, training programmes
had to last at least a minimum of 2 weeks, with participants
allocated to endurance training, HIT or a no-exercise
control group. Endurance training intensity was classified
as moderat e intensity (60–85 % maximum heart rate
[HR
max
]), with HIT intensity classified as ‘all-out’,
‘supramaximal’, ‘maximal’ or ‘high (90–95 % HR
max
)’.
Studies involving nutritional interventions were only
included if the intervention was used by all participants,
and stud ies were excluded if training was combined with
strength training.
2.2.4 Type of Outcome Measure
The outcome measure for this meta-analysis was maximal
oxygen uptake (VO
2max
).
2.3 Final Study Selection
Following database examination, 804 pote ntial manuscripts
were identified with another 17 selected on the basi s of the
reference lists of the potential manuscripts (Fig. 1). After
removal of duplicates and elimination of papers based on
title and abstract screening, 84 studies remained. The full
texts of the remaining papers were examined in more
detail. According to our eligibility criteria, 56 did not meet
the inclusion criteria leaving 28 studies that met our
inclusion criteria and were therefore included in the meta-
analysis (Table 1).
2.4 Data Extraction
Cochrane Consumers and Communication Review Group’s
data extraction protocol was used to extract participant
information including age, health status and sex, sample
size, description of the intervention (including type of
exercises, intensity, duration and frequency), study design
and study outcomes. This was undertaken by one author
(ZM) while GS checked the extracted data for accuracy and
completeness. Disagreements were resolved by consensus
or by a third reviewer. Reviewers were not blinded to
authors, institutions or manuscript journals. In those studies
where the data were shown in figures or graphs, either the
corresponding author was contacted to get the nume rical
data to enable analysis or graph digitizer software was used
to extract the necessary data (DigitiZelt, Germany).
HIT vs Endurance Training 1471
123
2.5 Assessment of Bias
Risk of bias was evaluated according to the PRISMA
recommendation [23] and two independent reviewers
assessed the risk of bias. Agreement between the two
reviewers was assessed using k statistics for full-text
screening, and rating of relevance and risk of bias. When
there was disagreement about the risk of bias, a third
reviewer checked the data and took the fin al decision on it.
The k agreement rate between reviewers was k = 0.95.
2.6 Statistical Analysis
A random effects meta-analysis was conducted to deter-
mine the pooled effect size of HIT and endurance training
on VO
2max
, using Comprehensive Meta-Analysis software,
Version 2 for Windows (Biostat company, Englewood, NJ,
USA). We performed separate analyses to determine the
pooled effect of the change in VO
2max
for endurance
training vs no exercise, HIT vs no exercise, and HIT vs
endurance training. The precision of the pooled effect was
reported as 95 % confidence limits (CL) and also as prob-
abilities that the true value of the effect was trivial, bene-
ficial or harmful in relation to threshold values for benefit
and harm. These probabilities were then used to make a
qualitative probabilistic inference about the overall effect
[24]. Given that enhanced aerobic functioning has clear
clinical applications [21], our meta-analysed effects were
assessed via clinical inferences. Here, the effects were
considered unclear if the chance of benefit (improved
VO
2max
) was high enough to warrant use of the intervention
but with an unacceptable risk of harm (reduced VO
2max
).
An odds ratio of benefit to harm of\66 was used to identify
such unclear effects. Inferences were then subsequently
Records identified through database
searching
(n = 804)
ScreeningIncluded
Eligibility
Identification
Additional records identified
through references list
(n = 17)
Records after duplicates removed
(n = 548)
Records screened by title or
abstract
(n = 316)
Records excluded after abstract
analysis
(n = 232)
Full-text articles assessed
for eligibility
(n = 84)
Full-text articles excluded, with
reasons
(n = 56)
Not original investigation (n=8)
Not relevant outcomes (n=22)
Not young adult (n=10)
Other (n=16)
Studies included in
qualitative and quantitative
synthesis (meta-analysis)
(n = 28)
Fig. 1 Flow diagram of the study selection process
1472 Z. Milanovic
´
et al.
123
Table 1 Summary of characteristics of all studies meeting the inclusion criteria
Study Population, age (year), no. of subjects, groups (n) Duration
(weeks)
Total
sessions
Group Exercise
intensity
No. of reps Total
reps
Reps
duration
(s)
Work/
rest
ratio
D
VO
2max
(%)
Outcomes and results
Start End
Astorino et al.
[26]
Recreational active men (n = 16) and women
(n = 13), age 25.3 ± 4.5 years
HIT (n = 20), CON (n = 9)
3 6 HIT All-out 4 6 30 30 0.10 6.1 HIT : VO
2max
, oxygen pulse and power output
NC in resting BP, HR and force production
Nybo et al. [27] Untrained inactive men (n = 36), age 20–43 years
HIT (n = 8), END (n = 9), CON (n = 11), STR
(n = 8)
12 36 HIT 95–100 %
HR
max
5 5 180 120 2.0 14.0 HIT was less efficient than END for resting
HR, fat percentage and ratio between total
and HDL cholesterol. END ; body mass and
fat percentage
NC in total bone mass and lean body mass in
HIT and END groups
36 END 80 % HR
max
3600 7.4
Osei-Tutu and
Campagna
[28]
Healthy Caucasian sedentary men and women
(n = 40), age 20–40 years
END (n = 15), CON (n = 10)
8 40 END 60–79 % HR
max
1800 7.2 VO
2max
: in END. END ; fat percentage
(-6.7 %), tension and total mood
disturbance
Trapp et al. [11] Healthy nonsmoking, inactive women (n = 45),
age 18–30 years
HIT (n = 15), END (n = 15), CON (n = 15)
15 45 HIT 95–100 %
HR
max
60 60 2700 8 0.67 26.4 HIT and END : VO
2max
compared with CON
group; only HIT ; total body mass, fat mass,
trunk fat and insulin level
NC in adiponectin levels in HIT and END
groups
45 END 75 % HR
max
1200–2400 19.4
Gormley et al.
[29]
Healthy young men and women (n = 61), age
18–44 years
HIT (n = 13), END (n = 13), CON (n = 14)
6 18 HIT 100 % HRR 5 5 90 300 1 20.2 HIT and END : VO
2max
NC in resting HR and BP in any group24 END 75 % HRR 2400 9.6
Ciolac et al. [30] Healthy young college women (n = 44), age
20–30 years
HIT (n = 16), END (n = 16), CON (n = 12)
16 48 HIT 80–90 %VO
2max
14 14 672 60 0.5 15.7 HIT and CON were equally ; ambulatory
blood pressure and ;; insulin
48 END 60–70 %
VO
2max
2400 8.0
Bayati et al. [31] Young active males (n = 16), age 25.0 ± 0.8
years
HIT (n = 8), CON (n = 8)
4 12 HIT 125 % P
max
6 10 96 30 0.25 9.7 HIT : power at VO
2max
(?16.1 %) and peak
power output (?7.4 %); blood lactate
recovery : in HIT compared with CON
NC in mean power output
Metcalfe et al.
[32]
Healthy sedentary young men and women
(n = 29), age 22.5 ± 2.0 years
HIT (n = 15), CON (n = 14)
6 18 HIT All-out 1 2 35 10–20 13.4 HIT : insulin sensitivity by 28 % in men
Ziemann et al.
[33]
Recreationally active men (n = 21), age
21.3 ± 1.0 years
HIT (n = 10), CON (n = 11)
6 18 HIT 80 % pVO
2max
6 6 108 90 0.5 11.0 HIT : anaerobic threshold
(3.8 mLkg
-1
min
-1
), work output
(12.5 Jkg
-1
), glycolytic work (11.5 Jkg
-1
),
mean power (0.3 W kg
-1
), peak power
(0.4 Wkg
-1
), and max power (0.4 Wkg
-1
)
Ben
Abderrahman
et al. [34]
Male physical education students (n = 15), age
20.6 ± 0.7 years
HIT (n = 9), CON (n = 6)
7 21 HIT 105–110 %
MAS
8 10 66 30 1 5.9 NC in time spent above 95 % of VO
2max
in
absolute and relative values
Burgomaster
et al. [35]
Healthy young men (n = 10) and women
(n = 10), age 23.56 ± 1.0 years
HIT (n = 10), END (n = 10)
6 18 HIT All-out 4 6 30 30 0.11 7.3 HIT and END : in mitochondrial markers for
skeletal muscle and lipid oxidation; both
groups : VO
2max
compared with control
group without changes between training
groups
NC in percentage of body fat and energy
intake in all groups
30 END 65 % VO
2peak
2400–3600 9.8
Chtara et al.
[36]
Male physical education students (n = 48), age
21.4 ± 1.3 years
HIT (n = 10), CON (n = 9)
12 24 END 100 % vVO
2max
5 5 120 9.8 HIT : in vVO
2max
10.38 %
HIT vs Endurance Training 1473
123
Table 1 continued
Study Population, age (year), no. of subjects, groups (n) Duration
(weeks)
Total
sessions
Group Exercise
intensity
No. of reps Total
reps
Reps
duration
(s)
Work/
rest
ratio
D
VO
2max
(%)
Outcomes and results
Start End
Hottenrott et al.
[6]
Recreational endurance men (n = 15) and women
(n = 15), age 43.4 ± 6.9 years
HIT (n = 14), END (n = 16)
12 36 HIT All-out 4 10 936 30 0.33 18.5 HIT and END :: peak oxygen uptake, resting
HR, V
LT
and visceral fat, body mass; END :
total body fat and fat-free mass compared
with HIT
NC in maximal lactate for both groups
24 END 75–85 % V
LT
1800–7200 7.0
Lo et al. [37] Healthy nonathletic men (n = 34), age
20.4 ± 1.36 years
HIT (n = 10), STR (n = 10), CON (n = 14)
24 72 END 75–85 % HRR 1800 20.5 END and STR : VO
2max
and lower body
strength; STR : upper body strength, lean
mass and body size of arm and calf
compared with END and CON groups
McKay et al.
[38]
Young adult men (n = 12), age 25.0 ± 4.0 years
HIT (n = 6), END (n = 6)
3 8 HIT 120 % WR
max
8 12 60 60 1 4.3 HIT and END : VO
2max
after training
programme; HIT and END ; time constant
for VO
2
response by *20 % after only
2 days of training and by *40 % post-
training, with no difference between groups
8 END 65 % VO
2max
5400–7200 7
Tabata et al.
[39]
Young male students (n = 14), age 23.0 ± 1.0
years
HIT (n = 7), END (n = 7)
6 30 HIT 170 % VO
2max
7 8 225 20 2 14.6 END did not increase anaerobic capacity but
:: in VO
2max
HIT :: VO
2max
by 7 mLkg
-1
min
-1
and
anaerobic capacity by 28 %
30 END 70 % VO
2max
3600 9.4
Cocks et al. [40] Young sedentary men (n = 16), age 21.0 ± 0.7
years
HIT (n = 8), END (n = 8)
6 18 HIT All-out 4 5 85 30 0.11 7.6 HIT and END : VO
2peak
and maximal power
output (END 16 %, HIT 9 %); both groups ;
in HRR, mean and diastolic BP with no
difference between group; NC in systolic BP
in both groups
30 END 65 % VO
2peak
2400–3600 15.6
Dunham and
Harms [41]
Physically active, healthy, untrained subjects
(n = 15), age 21.3 ± 2.3 years
HIT (n = 8), END (n = 7)
4 12 HIT 90 % VO
2max
5 5 60 60 0.33 9.6 HIT and END : VO
2max
and time trials
following training with no differences
between groups; HIT : in maximum
inspiratory pressure compared with END
NC in expiratory flow rates in both groups
12 END 60–70 %
VO
2max
2700 5.5
Edge et al. [42] Recreationally female students (n = 16), age
20.0 ± 1.0 years
HIT (n = 8), END (n = 8)
5 15 HIT 120–140 % LT 2 10 100 120 2 14.0 HIT and END : in VO
2peak
and the LT
(7–10 %), with no significant differences
between groups
NC in percentage of VO
2peak
at which LT
occurred
15 END 80–95 % LT 14
Esfarjani and
Laursen [43]
Healthy recreational men (n = 17), age 20.0 ± 2.0
years
HIT1 (n = 6), HIT2 (n = 6), END (n = 5)
10 20 HIT 75 % vVO
2max
5 8 130 200 1 9.2 HIT1 : in VO
2max
, vVO
2max
(?6.4 %), T
max
(5 %) and V
LT
(?11.7 %); HIT2 : in
VO
2max
, vVO
2max
(?7.8 %), T
max
(32 %),
and V
LT
(?11.7 %) but not V
LT
;NCin
these variables were found in END
HIT1: in VO
2max
and T
max
compared with
END
20 HIT 130 % vVO
2max
7 12 190 30 0.11 6.2
40 END 75 % vVO
2max
3600 2.1
Macpherson
et al. [44]
Healthy young recreationally active men (n = 12)
and women (n = 8), age 24.0 ± 3.0 years
HIT (n = 6), END (n = 5)
6 18 HIT All-out 4 6 90 30 0.11 11.5 HIT and END : body composition, 2000-run
time trial performance and VO
2max
; ft mass
; by 12.4 % with HIT and 5.8 % with END;
lean mass : 1 % in both groups. None of
these improvements differed between
groups
18 END 65 % VO
2max
1800–3600 12.5
Shepherd et al.
[45]
Healthy sedentary men (n = 16), age 21.5 ± 1.0
years
HIT (n = 8), END (n = 8)
6 18 HIT All-out 4 6 90 30 0.11 7.6 HIT and END :: VO
2peak
, fat-free mass, and
maximum workload; NC in relative fat mass
30 END 65 % VO
2peak
2400–3600 15.6
1474 Z. Milanovic
´
et al.
123
Table 1 continued
Study Population, age (year), no. of subjects, groups (n) Duration
(weeks)
Total
sessions
Group Exercise
intensity
No. of reps Total
reps
Reps
duration
(s)
Work/
rest
ratio
D
VO
2max
(%)
Outcomes and results
Start End
Helgerud et al.
[5]
Healthy nonsmoking men (n = 24), age
24.6 ± 3.8 years
HIT1 (n = 6), HIT2 (n = 6), END1 (n = 6),
END2 (n = 6)
8 24 HIT1 90–95 % HR
max
47 47 1128 15 1 6.4 HIT1 and HIT 2 :: VO
2max
compared with
END1 and END 2; percentage increases in
VO
2max
for the HIT1 and HIT 2 groups were
5.5 and 7.2 %, respectively. Stroke volume
of the heart : in HIT1 and HIT2
NC in blood volume, high-density lipoprotein
and low-density lipoprotein in any groups
after training programme
24 HIT2 90–95 % HR
max
4 4 96 240 1.33 8.8
24 END1 70 % HR
max
2700 1.8
24 END2 85 % HR
max
1455 2.0
Warburton et al.
[46]
Healthy untrained men (n = 20), age 30 ± 4 years
HIT (n = 6), END (n = 6), CON (n = 8)
12 36 HIT 90 % VO
2max
8 12 384 120 1 22.2 HIT and END :: VO
2max
and peak stroke
volume, blood volume compared to CON;
no differences between HIT and END in any
parameters
36 END 65 % VO
2max
1800–2880 23
Berger et al.
[47]
Healthy sedentary men (n = 11) and women
(n = 12), age 24 ± 5 years
HIT (n = 8), END (n = 8), CON (n = 7)
6 22 HIT 90 % VO
2max
15 20 445 60 1 21.0 HIT and END :: VO
2max
and pulmonary
VO
2max
kinetics, compared with CON
22 END 60 % VO
2max
1800 20.0
Matsuo et al.
[48]
Sedentary men (n = 42), age 26.5 ± 6.2 years
HIT (n = 14), END (n = 14)
8 40 HIT 80–85 %
VO
2max
3 3 120 180 1.5 22.5 HIT and END :: VO
2max
, HIT :: VO
2max
compared with END; only HIT :: left
ventricular mass, stroke volume and resting
HR
40 END 60–65 %
VO
2max
2400 10.0
O’Donovan
et al. [49]
Sedentary men (n = 42), age 41 ± 4
HIT (n = 13), END (n = 14), CON (n = 15)
24 72 HIT 80 % VO
2max
15.7 HIT and END :: VO
2max
, HIT : HDL and ;
LDL, NC in END for HDL and LDL
72 END 60 % VO
2max
22.5
Sandvei et al.
[50]
Healthy young men (n = 8) and women (n = 15),
age 25.2 ± 0.7 years
HIT (n = 11), END (n = 12)
8 24 HIT 100 % HR
max
5 10 189 30 0.16 5.3 HIT and END : VO
2max
, HIT : insulin
sensitivity and cholesterol profile while NC
for END
24 END 70–80 % HR
max
1800–3600 3.8
BP blood pressure, CON control group, END continuous endurance training, HDL high-density lipoprotein, HIT high-intensity interval training, HR heart rate, HR
max
maximum heart rate, HRR heart rate reserve, LT lactate threshold,
MAS maximal aerobic speed, max maximal, NC no changes p [ 0.05, P
max
power at VO
2max
, pVO
2max
maximal aerobic power, rep repetitions, STR strength training, T
max
time to exhaustion at vVO
2max
, V
LT
velocity of the lactate
threshold, VO
2max
maximal oxygen uptake, VO
2peak
peak rate of oxygen consumption, vVO
2max
running speed at VO
2max
, WR
max
work rate at maximal O
2
uptake, : indicates significant increase p \ 0.05, :: indicates significant
increase p \ 0.01, ; indicates significant decreases p \ 0.05, ;; indicates significant decreases p \ 0.01
HIT vs Endurance Training 1475
123
based on standardised thresholds for small, moderate and
large changes of 0.2, 0.6 and 1.2 standard deviations (SDs),
respectively [24] and derived by averaging appropriate
between-subject variances for baseline VO
2max
. Magnitude
thresholds were 0.8, 2.4 and 4.7 mLkg
-1
min
-1
(en-
durance vs no exercise), 0.8, 2.3 and 4.7 mLkg
-1
min
-1
(HIT vs no exercise) and 0.9, 2.6 and 5.3 mLkg
-1
min
-1
(HIT vs endurance training). The chance of the true effect
being trivial, beneficial or harmful was then interpreted
using the following scale: 25–75 %, possibly; 75–95 %,
likely; 95–99.5 %, very likely; [99.5 %, most likely [24].
Random variation in the effect from study to study was
expressed as an SD, with the SD doubled to interpret its
magnitude [25]. Publication bias was assessed by examin-
ing asymmetry of funnel plots using Egger’s test, and a
significant publication bias was considered if the p \ 0.10.
2.7 Meta-Regression Analysis
Meta-regression analyses were conducted to explore the
effect of putative moderator variables on the pooled effect.
Here, we selected five moderator variables that could rea-
sonably influence the overall effect of training on VO
2max
and these were age, baseline fitness, intervention duration,
work:rest ratio and HIT repetition duration. The modifying
effects of these five variables were calculated as the effect
of two SDs (i.e. the difference between a typically low and
a typically high value) [24].
3 Results
The Egger’s test was performed to provide statistical evi-
dence of funnel plot asymmetry (Fig. 2) and the results
indicated publication bias for all analyses (p \ 0.10).
3.1 Endurance Training vs No-Exercise Controls
The meta-analysed effect of endurance training, when
compared with controls, was a possibly large beneficial
effect on VO
2max
(4.9 mLkg
-1
min
-1
;95%CL
±1.4 mLkg
-1
min
-1
) (Fig. 3; Table 2). Meta-regression
analysis revealed a greater beneficial effect (possibly
moderate) for typically younger vs older subjects and
interventions of longer duration, and a greater beneficial
improvement (possibly small) for subjects with typically
lower baseline fitness. The random variation in the overall
pooled effect from study to study, expressed as an SD, was
1.3 mLkg
-1
min
-1
.
3.2 High-Intensity Interval Training (HIT) vs No-
Exercise Controls
The meta-analysed effect of HIT, when compared with
controls, was a likely large beneficial effect on VO
2max
(5.5 mLkg
-1
min
-1
; ±1.2 mLkg
-1
min
-1
) (Fig. 4;
Table 3). Meta-regression analysis revealed a likely mod-
erate greater beneficial improvement in VO
2max
for sub-
jects with typically lower baseline fitness and interventions
of longer duration and a likely small lesser effect for longer
HIT repetitions. The effects of all other puta tive modifiers
were unclear. Random variation in the effect from study to
study was 1.3 mLkg
-1
min
-1
.
3.3 HIT vs Endurance Training
When compared wi th endurance training, there was a
possibly small beneficial effect of HIT on VO
2max
(1.2 mLkg
-1
min
-1
; ±0.9 mLkg
-1
min
-1
) (Fig. 5;
Table 4). The modify ing effects of typically longer HIT
repetitions, older and less fit subjects, longer interventions
Fig. 2 Funnel plot of standard
difference in means vs standard
error; the aggregated standard
difference in means is the
random effects mean effect size
weighted by degrees of freedom
1476 Z. Milanovic
´
et al.
123
and a greater work:rest ratio were possibly to likely small
increased beneficial improvements in VO
2max
. Random
variation in the effect from study to study was
0.8 mLkg
-1
min
-1
.
4 Discussion
This study presents a quantitative evaluation of HIT and
endurance training models for VO
2max
improvements in
healthy adul ts aged 18–45 years. Our results show that
when compared with no-exercise controls, both types of
training elicit large improvements in VO
2max
. In studies
where HIT and endurance were directly compared, there
was a small beneficial effect for HIT.
The results of our systematic review and meta-analysis
confirm the conclusions of previous studies [11, 2730, 36,
37, 51] that continuous aerobic endur ance training is an
effective method for VO
2max
improvement in young adults.
The training effect was greater for less fit adults, which is
consistent with previous work demonstrating that aerobic
training has an adaptive effect that favours the less fit [21].
Further to this, the beneficial effect of continuous endur-
ance training on VO
2max
is greater for younger subjects and
with interventions of longer duration. Most of the studies in
this particular analysis undertook three moderate-intensity
sessions per week lasting 40–60 min, yet the American
College of Sports Medicine (ACSM) recommends to
undertake moderate-intensity continuous exercises for a
minimum of 30 min on 5 days each week or 20 min of
vigorous exercises 3 days each week, or a combination of
the two [52]. As such, it is clear from the findings of this
review that substantial gains in aerobic fitness can be
obtained with a moderate-intensity training session fre-
quency lower than that currently recommend [2].
When compared with no-exercise controls, HIT elicits a
likely large substantial improvement in the VO
2max
of
healthy adults. The size of this effect was greater than that
-20.0 -10.0 0.0 10.0 20.0
Bayati et al. [31]
Astorino et al. [26]
Esfarjani and Laursen [43]
Ben Abderrahman et al. [34]
Ciolac et al. [30]
Ziemann et al. [33]
Metcalfe et al. [32]
Nybo et al. [27]
Gormley et al. [29]
Berger et al. [47]
O' Donovan et al. [49]
Trapp et al. [11]
Warburton et al. [46]
Overall
Favours
control
Favours
HIT
Study name
Mean difference (mL·kg
-1
·min
-1
)
with 95% CL
Fig. 4 Effects of HIT vs no-exercise controls on maximal oxygen
uptake. CL confidence limits, HIT high-intensity interval training
Table 2 Effects of endurance training on VO
2max
Effect on VO
2max
(mLkg
-1
min
-1
) Inference
Mean ±95 % CL
Main effect
Endurance training vs control 4.9 ±1.4 Possibly large :
Modifying effects
a
Age lower by 13.7 years 2.4 ±2.1 Possibly moderate :
Intervention duration longer by 13 weeks 2.2 ±3.0 Possibly moderate :
Baseline VO
2max
lower by 12.6 mLkg
-1
min
-1
1.4 ±2.0 Possibly small :
CL confidence limits, VO
2max
maximal oxygen uptake, : indicates increase
a
Modifying effects are presented as the effect of two standard deviations of the numerical covariates (i.e. a typically high value minus a
typically low value)
-20.0 -10.0 0.0 10.0 20.0
Favours
control
Favours
endurance training
Ciolac et al. [30]
Gormley et al. [29]
Nybo et al. [27]
Osei-Tutu and Campagna [28]
Chtara et al. [36]
O' Donovan et al. [49]
Lo et al. [37]
Berger et al. [47]
Trapp et al. [11]
Warburton et al. [46]
Overall
Study name
Mean difference (mL·kg
-1
·min
-1
)
with 95% CL
Fig. 3 Effects of endurance training vs no-exercise controls on
maximal oxygen uptake. CL confidence limits
HIT vs Endurance Training 1477
123
reported by Gist et al. [19], who reported a moderate effect
(effect size 0.69) for low-volume HIT when compared with
no-exercise controls, with differences in the overall dose of
exercise possibly accounting for these inconsistent results.
Irrespective of dose, HIT has a clear beneficial effect on the
aerobic fitness of healthy young adults when compared
with no exercise. This effect is moderated by initial fitness
as the training benefits individuals with lower initial fit-
ness—a finding consistent with low-volume HIT pro-
grammes [21]. With regard to HIT programming, a
moderating beneficial effect for longer intervention
duration is consistent with the subgroup analysis performed
by Bacon et al. [18]. Here, the authors reported that the
largest increases in VO
2max
were following longer inter-
vention durations (p = 0.004). Additionally, we found an
unclear effect on VO
2max
with an increased work:rest ratio
(e.g. greater recovery between HIT repetitions), a finding
consistent with that reported by Weston et al. [21]. Future
studies are therefore needed to resolve this unclear effect,
although the prescription of an ‘optimal’ work:rest ratio is
challenging as variables such as age, sex, baseline fitness
and training experience may need to be considered when
designing HIT programmes. We also found an unclear
modifying effect of age on HIT and consistent with pre-
vious HIT meta-analyses [18, 19, 21], the dem ographic of
participants in the studies analysed was mainly young
adults. As such, we suggest that more HIT studies need to
be undertaken in older populations, especially given the
recent encouraging findings reported by Adamson et al.
[53] and Knowles et al. [54] whereby HIT elicited sub-
stantial improvements in VO
2max
and also measures of
functional fitness and quality of life.
When compared with endurance training controls, HIT
had a possibly small beneficial effect on VO
2max
. Previous
comparisons between HIT and endurance training yielded
either an unclear effect [19, 21] or a significantly higher
increase in VO
2peak
after HIT compared with endurance
training (3.03 mLkg
-1
min
-1
; ±2.0 to 4.1 mLkg
-1-
min
-1
)[21]. Discrepancies in the overall training dose (e.g.
low-volume HIT vs HIT) and study participants (e.g.
healthy participants vs patient populations) no doubt
account for the inconsistency in these findings. The dif-
ference in the training effect between HIT and endurance
was enhanced for older and less fit subjects, suggesting
Table 3 Effects of HIT on VO
2max
Effect on VO
2max
(mLkg
-1
min
-1
) Inference
Mean ±95 % CL
Main effect
HIT vs control 5.5 ±1.2 Likely large :
Modifying effects
a
Baseline VO
2max
lower by 18.5 mLkg
-1
min
-1
3.2 ±1.9 Likely moderate :
Intervention duration longer by 13 weeks 3.0 ±1.9 Likely moderate :
Age higher by 11.7 years 0.8 ±2.1 Unclear
Work:rest ratio higher by 1.1 0.5 ±1.6 Unclear
HIT repetition duration longer by 161 s -1.8 ±2.7 Likely small ;
CL confidence limits, HIT high-intensity interval training, VO
2max
maximal oxygen uptake, : indicates increase, ; indicates decrease
a
Modifying effects are presented as the effect of two standard deviations of the numerical covariates (i.e. a typically high value minus a
typically low value)
-20.0 -10.0 0.0 10.0 20.0
Cocks et al. [40]
Shepherd et al. [45]
McKay et al. [38]
Edge et al. [42]
Macpherson et al. [44]
Berger et al. [47]
Warburton et al. [46]
Sandvei et al. [50]
Burgomaster et al. [35]
Dunham and Harms [41]
Trapp et al. [11]
Tabata et al. [39]
Nybo et al. [27]
Ciolac et al. [30]
O' Donovan et al. [49]
Gormley et al. [29]
Helgerud et al. [5]
Hottenrott et al. [6]
Matsuo et al. [48]
Overall
Study name
Mean difference (mL·kg
-1
·min
-1
)
with 95% CL
Favours endurance
training
Favours
HIT
Fig. 5 Effects of HIT vs endurance training on maximal oxygen
uptake. CL confidence limits, HIT high-intensity interval training
1478 Z. Milanovic
´
et al.
123
HIT to have appeal for those involved in the fitness pro-
gramming of older adults and patient populations, espe-
cially given that the safety concerns associated with HIT
are unfounded [55, 56]. Our supposition is supported by
recent evidence whereby HIT induced substantial
improvements in cardiovascular (e.g. VO
2max
), functional
fitness (e.g. sit-to-sta nd test) and health- related quality of
life/physical functioning following short (3 weeks) [53]
and long duration (13 weeks) [54] interventions. Our
findings of enhanced beneficial effects for HIT with longer
repetitions, greater work:rest ratios and longer training
interventions provides valuable information to those
involved in the design and implementation of HIT
programmes.
While information on the physiological mechanisms
subtending the improvements in VO
2max
following either
endurance training or HIT helps to explain changes in
VO
2max
, a discussion of physiological adaptations is
beyond the scope of our review. In this instanc e, we direct
readers to the articulate and comprehensive reviews of
Jones and Carter [57], Gibala et al. [58] and Sloth et al.
[20] for a detailed discussion of the underlying physio-
logical adaptations to endurance training and HIT.
Finally, the observed magnitude of the between-study
variation in the mean effect was moderate for endurance
training vs control and HIT vs control, and small for HIT vs
endurance training. As such, the mean effect, when com-
pared with control, lies typically between 3.6 mLkg
-1-
min
-1
(very likely moderate) and 6.2 mLkg
-1
min
-1
(very likely large) for endurance training, betwee n
4.2 mLkg
-1
min
-1
(most likely moderate) and
6.8 mLkg
-1
min
-1
(very likely large) for HIT, and
between -0.4 mLkg
-1
min
-1
(most likely trivial) and
2.0 mLkg
-1
min
-1
(likely small) for HIT compared with
endurance training.
5 Conclusion
Our meta-analysi s confirms that endurance training and
HIT both elicit large improvements in the VO
2max
of
healthy, young to middle-a ged adults with the effects being
greater for the less fit. Furthermore, when comparing the
two modes of training, the gains in VO
2max
are greater
following HIT. Given the well established link between
aerobic fitness and mortality, further investigations into the
manipulations of the HIT dose (e.g. repe tition intensity,
duration, work:rest ratio etc.) are therefore recommended
to enhance our understanding of the beneficial effects of
HIT.
Compliance with Ethical Standards No sources of funding were
used to assist in the preparation of this review. The authors have
no conflicts of interest that are directly relevant to the content of
this review.
References
1. Lee D, Sui X, Artero EG, et al. Long-term effects of changes in
cardiorespiratory fitness and body mass index on all-cause and
cardiovascular disease mortality in men: the aerobics center
longitudinal study. Circulation. 2011;124(23):2483–90.
2. Lee D, Artero EG, Sui X, et al. Review: mortality trends in the
general population: the importance of cardiorespiratory fitness.
J Psychopharmacol (Oxf). 2010;24(4):27–35.
3. Myers J, Prakash M, Froelicher V, et al. Exercise capacity and
mortality among men referred for exercise testing. N Engl J Med.
2002;346(11):793–801.
4. Zuhl M, Kravitz L. Hiit vs. continuous endurance training: battle
of the aerobic titans. IDEA Fit J. 2012;9(2):35–40.
5. Helgerud J, Hoydal K, Wang E, et al. Aerobic high-intensity
intervals improve VO
2max
more than moderate training. Med Sci
Sports Exerc. 2007;39(4):665.
6. Hottenrott K, Ludyga S, Schulze S. Effects of high intensity
training and continuous endurance training on aerobic capacity
Table 4 Effects of HIT vs endurance training on VO
2max
Effect on VO
2max
(mLkg
-1
min
-1
) Inference
Mean ±95 % CL
Main effect
HIT vs endurance training 1.2 ±0.9 Possibly small :
Modifying effects
a
HIT repetition duration longer by 164 s 2.2 ±2.1 Likely small :
Age higher by 12.9 years 1.8 ±1.7 Likely small :
Intervention duration longer by 10.3 weeks 1.7 ±1.7 Likely small :
Work:rest ratio higher by 1.4 1.6 ±1.5 Likely small :
Baseline VO
2max
lower by 14.5 mLkg
-1
min
-1
0.8 ±1.3 Possibly small :
CL confidence limits, HIT high-intensity interval training, VO
2max
maximal oxygen uptake, : indicates increase
a
Modifying effects are presented as the effect of two standard deviations of the numerical covariates (i.e. a typically high value minus a
typically low value)
HIT vs Endurance Training 1479
123
and body composition in recreationally active runners. J Sports
Sci Med. 2012;11:483–8.
7. Oja P, Titze S, Bauman A, et al. Health benefits of cycling: a
systematic review. Scand J Med Sci Sports. 2011;21(4):496–509.
8. Whyte LJ, Gill JM, Cathcart AJ. Effect of 2 weeks of sprint
interval training on health-related outcomes in sedentary over-
weight/obese men. Metabolism. 2010;59(10):1421–8.
9. Laursen PB, Jenkins DG. The scientific basis for high-intensity
interval training: optimising training programmes and maximis-
ing performance in highly trained endurance athletes. Sports
Med. 2002;32(1):53–73.
10. Daussin FN, Zoll J, Dufour SP, et al. Effect of interval versus
continuous training on cardiorespiratory and mitochondrial
functions: relationship to aerobic performance improvements in
sedentary subjects. Am J Physiol Regul Integr Comp Physiol.
2008;295(1):R264–72.
11. Trapp E, Chisholm D, Freund J, et al. The effects of high-in-
tensity intermittent exercise training on fat loss and fasting
insulin levels of young women. Int J Obes. 2008;32(4):684–91.
12. Tremblay A, Simoneau J-A, Bouchard C. Impact of exercise
intensity on body fatness and skeletal muscle metabolism.
Metabolism. 1994;43(7):814–8.
13. Wisløff U, Ellingsen Ø, Kemi OJ. High-intensity interval training
to maximize cardiac benefits of exercise training? Exerc Sport Sci
Rev. 2009;37(3):139–46.
14. Weston KS, Wisløff U, Coombes JS. High-intensity interval
training in patients with lifestyle-induced cardiometabolic dis-
ease: a systematic review and meta-analysis. Br J Sports Med.
2014;48(16):1227–34.
15. Hwang C-L, Wu Y-T, Chou C-H. Effect of aerobic interval
training on exercise capacity and metabolic risk factors in people
with cardiometabolic disorders: a meta-analysis. J Cardiopulm
Rehabil Prev. 2011;31(6):378–85.
16. Guiraud T, Nigam A, Gremeaux V, et al. High-intensity interval
training in cardiac rehabilitation. Sports Med. 2012;42(7):587–605.
17. Kessler HS, Sisson SB, Short KR. The potential for high-intensity
interval training to reduce cardiometabolic disease risk. Sports
Med. 2012;42(6):489–509.
18. Bacon AP, Carter RE, Ogle EA, et al. VO
2max
trainability and
high intensity interval training in humans: a meta-analysis. PLoS
One. 2013;8(9):e73182.
19. Gist NH, Fedewa MV, Dishman RK, et al. Sprint interval training
effects on aerobic capacity: a systematic review and meta-anal-
ysis. Sports Med. 2014;44(2):269–79.
20. Sloth M, Sloth D, Overgaard K, et al. Effects of sprint interval
training on VO
2max
and aerobic exercise performance: a sys-
tematic review and meta-analysis. Scand J Med Sci Sports.
2013;23(6):e341–52.
21. Weston M, Taylor KL, Batterham AM, et al. Effects of low-
volume high-intensity interval training (hit) on fitness in adults: a
meta-analysis of controlled and non-controlled trials. Sports Med.
2014;44(7):1005–17.
22. Moher D, Liberati A, Tetzlaff J, et al. Preferred reporting items
for systematic reviews and meta-analyses: the prisma statement.
PLoS Med. 2009;6(7):e1000097.
23. Liberati A, Altman DG, Tetzlaff J, et al. The prisma statement for
reporting systematic reviews and meta-analyses of studies that
evaluate health care interventions: explanation and elaboration.
PLoS Med. 2009;6(7):e1000100.
24. Hopkins WG, Marshall SW, Batterham AM, et al. Progressive
statistics for studies in sports medicine and exercise science. Med
Sci Sports Exerc. 2009;41(1):3–13.
25. Smith TB, Hopkins WG. Variability and predictability of finals
times of elite rowers. Med Sci Sports Exerc.
2011;43(11):2155–60.
26. Astorino TA, Allen RP, Roberson DW, et al. Effect of high-
intensity interval training on cardiovascular function, VO
2max
,
and muscular force. J Srength Cond Res. 2012;26(1):138.
27. Nybo L, Sundstrup E, Jakobsen MD, et al. High-intensity training
versus traditional exercise interventions for promoting health.
Med Sci Sports Exerc. 2010;42(10):1951–8.
28. Osei-Tutu KB, Campagna PD. The effects of short- vs. long-bout
exercise on mood, VO
2max
, and percent body fat. Prev Med.
2005;40(1):92–8.
29. Gormley SE, Swain DP, High R, et al. Effect of intensity of
aerobic training on VO
2max
. Med Sci Sports Exerc.
2008;40(7):1336–43.
30. Ciolac EG, Bocchi EA, Bortolotto LA, et al. Effects of high-
intensity aerobic interval training vs. moderate exercise on
hemodynamic, metabolic and neuro-humoral abnormalities of
young normotensive women at high familial risk for hyperten-
sion. Hypertens Res. 2010;33(8):836–43.
31. Bayati M, Farzad B, Gharakhanlou R, et al. A practical model of
low-volume high-intensity interval training induces performance
and metabolic adaptations that resemble’all-out’sprint interval
training. J Sports Sci Med. 2011;10:571–6.
32. Metcalfe RS, Babraj JA, Fawkner SG, et al. Towards the minimal
amount of exercise for improving metabolic health: beneficial
effects of reduced-exertion high-intensity interval training. Eur J
Appl Physiol. 2011;112(7):2767–75.
33. Ziemann E, Grzywacz T, Luszczyk M, et al. Aerobic and
anaerobic changes with high-intensity interval training in active
college-aged men. J Srength Cond Res. 2011;25(4):1104.
34. Abderrahman AB, Zouhal H, Chamari K, et al. Effects of
recovery mode (active vs. passive) on performance during a short
high-intensity interval training program: a longitudinal study. Eur
J Appl Physiol. 2012;113(6):1373–83.
35. Burgomaster KA, Howarth KR, Phillips SM, et al. Similar
metabolic adaptations during exercise after low volume sprint
interval and traditional endurance training in humans. J Physiol.
2008;586(1):151–60.
36. Chtara M, Chamari K, Chaouachi M, et al. Effects of intra-ses-
sion concurrent endurance and strength training sequence on
aerobic performance and capacity. Br J Sports Med.
2005;39(8):555–60.
37. Lo MS, Lin LL, Yao W-J, et al. Training and detraining effects of
the resistance vs. endurance program on body composition, body
size, and physical performance in young men. J Srength Cond
Res. 2011;25(8):2246–54.
38. McKay BR, Paterson DH, Kowalchuk JM. Effect of short-term
high-intensity interval training vs. continuous training on O
2
uptake kinetics, muscle deoxygenation, and exercise perfor-
mance. J Appl Physiol. 2009;107(1):128–38.
39. Tabata I, Nishimura K, Kouzaki M, et al. Effects of moderate-
intensity endurance and high-intensity intermittent training on
anaerobic capacity and VO
2max
. Med Sci Sports Exerc.
1996;28(10):1327.
40. Cocks M, Shaw CS, Shepherd SO, et al. Sprint interval and
endurance training are equally effective in increasing muscle
microvascular density and enos content in sedentary males.
J Physiol (Lond). 2013;591(Pt 3):641–56.
41. Dunham C, Harms CA. Effects of high-intensity interval training
on pulmonary function. Eur J Appl Physiol. 2012;112(8):3061–8.
42. Edge J, Bishop D, Goodman C. The effects of training intensity
on muscle buffer capacity in females. Eur J Appl Physiol.
2006;96(1):97–105.
43. Esfarjani F, Laursen PB. Manipulating high-intensity interval
training: effects on VO
2max
, the lactate threshold and 3000 m
running performance in moderately trained males. J Sci Med
Sport. 2007;10(1):27.
1480 Z. Milanovic
´
et al.
123
44. Macpherson R, Hazell TJ, Olver TD, et al. Run sprint interval
training improves aerobic performance but not maximal cardiac
output. Med Sci Sports Exerc. 2011;43(1):115–22.
45. Shepherd SO, Cocks M, Tipton KD, et al. Sprint interval and
traditional endurance training increase net intramuscular triglyc-
eride breakdown and expression of perilipin 2 and 5. J Physiol.
2013;591(3):657–75.
46. Warburton D, Haykowsky MJ, Quinney HA, et al. Blood volume
expansion and cardiorespiratory function: effects of training
modality. Med Sci Sports Exerc. 2004;36(6):991–1000.
47. Berger NJ, Tolfrey K, Williams AG, et al. Influence of continu-
ous and interval training on oxygen uptake on-kinetics. Med Sci
Sports Exerc. 2006;38(3):504–12.
48. Matsuo T, Saotome K, Seino S, et al. Effects of a low-volume
aerobic-type interval exercise on VO
2max
and cardiac mass. Med
Sci Sports Exerc. 2014;46(1):42–50.
49. O’Donovan G, Owen A, Bird SR, et al. Changes in cardiorespi-
ratory fitness and coronary heart disease risk factors following 24
wk of moderate- or high-intensity exercise of equal energy cost.
J Appl Physiol. 2005;98(5):1619–25.
50. Sandvei M, Jeppesen PB, Støen L, et al. Sprint interval running
increases insulin sensitivity in young healthy subjects. Arch
Physiol Biochem. 2012;118(3):139–47.
51. Geliebter A, Maher MM, Gerace L, et al. Effects of strength or
aerobic training on body composition, resting metabolic rate, and
peak oxygen consumption in obese dieting subjects. Am J Clin
Nutr. 1997;66(3):557–63.
52. Haskell WL, Lee I, Pate RR, et al. Physical activity and public
health: updated recommendation for adults from the american
college of sports medicine and the american heart association.
Med Sci Sports Exerc. 2007;39(8):1423.
53. Adamson SB, Lorimer R, Cobley JN, et al. Extremely short-
duration high-intensity training substantially improves the phys-
ical function and self-reported health status of elderly adults.
J Am Geriatr Soc. 2014;62(7):1380–1.
54. Knowles A-M, Herbert P, Easton C, et al. Impact of low-volume,
high-intensity interval training on maximal aerobic capacity,
health-related quality of life and motivation to exercise in ageing
men. Age. 2015;37(2):1–12.
55. Wisløff U, Støylen A, Loennechen JP, et al. Superior cardio-
vascular effect of aerobic interval training versus moderate con-
tinuous training in heart failure patients a randomized study.
Circulation. 2007;115(24):3086–94.
56. Currie KD, Bailey KJ, Jung ME, et al. Effects of resistance
training combined with moderate-intensity endurance or low-
volume high-intensity interval exercise on cardiovascular risk
factors in patients with coronary artery disease. J Sci Med Sport.
2014. doi:10.1016/j.jsams.2014.09.013.
57. Jones AM, Carter H. The effect of endurance training on
parameters of aerobic fitness. Sports Med. 2000;29(6):373–86.
58. Gibala MJ, Little JP, MacDonald MJ, et al. Physiological adap-
tations to low-volume, high-intensity interval training in health
and disease. J Physiol. 2012;590(5):1077–84.
HIT vs Endurance Training 1481
123
... Steckling et al. (47) in line with our findings, also considered HIIT training as an efficient strategy to improve cardiorespiratory fitness and functional parameters of individuals with obesity. Studies show that HIIT requires less time than conventional moderate-intensity exercise options to obtain health benefits including increased aerobic fitness which corroborates with the present study (48)(49)(50). ...
... In the present study, we observed a high number of dropouts in the three groups, but especially in the IF group, which means that there was low adherence to the proposed protocol. Adherence to IF is challenging and some aspects such as susceptibility to over-eating and possible adverse effects, have been associated with loss to follow-up or discontinued intervention in different IF protocols (50,52). ...
Article
Full-text available
Background Intermittent fasting (IF) is a dietary approach that is widely popular due to its effects on weight and body fat loss, but it does not appear to ensure muscle mass preservation. Incorporating high-intensity interval training (HIIT) into an individual’s routine could be an attractive and viable therapeutic option for improving body composition, lifestyle and health promotion. Problematizing the emerging situation of fighting obesity, led us to clarify gaps about IF and hypothesize that IF and HIIT in conjunction may protect against muscle mass decline without impairing nitrogen balance (NB), in addition to improving the physical fitness of women with obesity. Objectives To evaluate the effects of IF alone and combined with HIIT on body composition, NB and strength and physical fitness in women with obesity. Methods Thirty-six women (BMI 34.0 ± 3.2; 32.2 ± 4.4 years) participated and were randomly distributed into three groups: (1) Intermittent fasting combined with exercise group (IF + EX); (2) Exercise group (EX); and (3) Intermittent fasting group (IF). The interventions took place over 8 weeks and all evaluations were performed pre and post-intervention. The HIIT circuit was performed 3x/week, for 25 mins/session, at 70–85% of the maximum heart rate. The intermittent fasting protocol was a 5:2 diet with two meals within 6 h on fasting days, being 25% of total energy intake, plus 18 h of complete fasting. The protocol was performed 2x/week and 5 days of ad libitum ingestion. Resting metabolic rate (RMR) was measured by indirect calorimetry, body composition by BodPod ® , NB from urinary nitrogen, food consumption by food records and physical and strength performance were measured by physical tests. ANOVA two-way repeated measures mixed model was performed followed by Sidak post hoc ( p < 0.05). This project was registered in ClinicalTrials.gov , NCT05237154. Results There were a reduction in body weight ( P = 0.012) and BMI ( P = 0.031) only in the IF + EX group. There was body fat loss in the IF + EX group (−4%, P < 0.001) and in the EX group (−2.3%, P = 0.043), an increase in fat-free mass in the IF + EX group (+3.3%, P < 0.001) and also in the EX group (+2%, P = 0.043), without differences between groups and the IF group showed no changes. The NB was equilibrium in all groups. All parameters of aerobic capacity and strength improved. Conclusion Combining IF with HIIT can promote increments in fat-free mass, NB equilibrium and improve physical fitness and strength.
... Aerobic intensity can be divided into five zones: Zone 1 at 50-60 % VO₂max, Zone 2 at 66-80 % VO₂max, Zone 3 at 811-87 % VO₂max, Zone 4 at 88-93 % VO₂max, and Zone 5 at 94-100 % VO₂max [19]. Classic aerobic/resistance training increases cardiac output, oxygen consumption, and mitochondrial biogenesis [2,20,21]. Physical training improves the central and peripheral tissues, increasing the ability of individuals to run, swim, and cycle for greater distances [22]. On the other hand, strength training results in an increase in muscle size (cross-sectional area), neural adaptations (motor output), and strength improvement (maximum force production) [2,3]. ...
Article
Full-text available
MicroRNAs (miRNAs) control RNA translation and are a class of small, tissue-specific, non-protein-coding RNAs that maintain cellular homeostasis through negative gene regulation. Maintenance of the physiological environment depends on the proper control of miRNA expression, as these molecules influence almost all genetic pathways, from the cell cycle checkpoint to cell proliferation and apoptosis, with a wide range of target genes. Dysregulation of the expression of miRNAs is correlated with several types of diseases, acting as regulators of cardiovascular functions, myogenesis, adipogenesis, osteogenesis, hepatic lipogenesis, and important brain functions. miRNAs can be modulated by environmental factors or external stimuli, such as physical exercise, and can eventually induce specific and adjusted changes in the transcriptional response. Physical exercise is used as a preventive and non-pharmacological treatment for many diseases. It is well established that physical exercise promotes various benefits in the human body such as muscle hypertrophy, mental health improvement, cellular apoptosis, weight loss, and inhibition of cell proliferation. This review highlights the current knowledge on the main miRNAs altered by exercise in the skeletal muscle, cardiac muscle, bone, adipose tissue, liver, brain, and body fluids. In addition, knowing the modifications induced by miRNAs and relating them to the results of prescribed physical exercise with different protocols and intensities can serve as markers of physical adaptation to training and responses to the effects of physical exercise for some types of chronic diseases. This narrative review consists of randomized exercise training experiments with humans and/or animals, combined with analyses of miRNA modulation.
... Participants with moderate activity levels are those who practice at least half an hour of physical activity of moderate intensity almost every day. Participants with low activity levels are those without moderate or high activity levels (Milanovi'c et al. 2015). The short version of the questionnaire used in this study asked participants to answer seven items related to the physical activity that they carried out during the past seven days (three of the items are quantified in days and four items in hours and minutes). ...
Article
Full-text available
The factors that make physically active older people feel more satisfied in adulthood have not been extensively studied. For this reason, the aim of this work has been to evaluate, among physically active older adults, whether the level of physical activity they perform and the factors that foster their quality of life can be predictors of their satisfaction with life. For this, the IPAQ, CUBRECAVI and LSI-A scales were applied to a sample of 397 people between 61 and 93 years old (M = 69.65, SD = 4.71). The results show that health (β = 0.373), functional abilities (β = 0.159) and environmental quality (β = 0.105) are predictors of satisfaction in the most active adults. In conclusion, neither physical activity (to a greater or lesser extent) nor income are predictive variables of satisfaction with life but, rather, predict some of the components that cement their quality of life (health, fending for themselves and the home environment).
... For instance, resistance exercise training interventions maximize neuromuscular adaptations, such as muscle hypertrophy and strength (Campos et al., 2002;Mitchell et al., 2013;Bellamy et al., 2014;Nader et al., 2014;Damas et al., 2016;Morton et al., 2019). On the other hand, aerobic exercise training interventions improve aerobic muscle metabolism and cardiorespiratory fitness (e.g., aerobic power) (Maeda et al., 2001;Coffey and Hawley, 2007;Daussin et al., 2007;Sloth et al., 2013;Konopka et al., 2014;Milanovic et al., 2015). Besides different functional and morphological adaptations, distinct exercise modes can also affect myokines secretion (Trovato et al., 2019). ...
Article
Full-text available
Losses in skeletal muscle mass, strength, and metabolic function are harmful in the pathophysiology of serious diseases, including breast cancer. Physical exercise training is an effective non-pharmacological strategy to improve health and quality of life in patients with breast cancer, mainly through positive effects on skeletal muscle mass, strength, and metabolic function. Emerging evidence has also highlighted the potential of exercise-induced crosstalk between skeletal muscle and cancer cells as one of the mechanisms controlling breast cancer progression. This intercellular communication seems to be mediated by a group of skeletal muscle molecules released in the bloodstream known as myokines. Among the myokines, exercise-induced circulating microRNAs (c-miRNAs) are deemed to mediate the antitumoral effects produced by exercise training through the control of key cellular processes, such as proliferation, metabolism, and signal transduction. However, there are still many open questions regarding the molecular basis of the exercise-induced effects on c-miRNA on human breast cancer cells. Here, we present evidence regarding the effect of exercise training on c-miRNA expression in breast cancer, along with the current gaps in the literature and future perspectives.
... Whilst prolonged sitting time and sedentary behaviour increase the risk of all-cause mortality, 60 to 75 min of at least moderate-intensity exercise per day appears sufficient to attenuate this risk [2]. Regular participation in endurance exercise increases cardiorespiratory fitness [3] and lowers the risk of chronic diseases and associated risk factors [4]. Additionally, resistance training effectively increases muscle strength (1-repetition maximum) and size (muscle cross-sectional area), which also reduces the risk of age-related chronic diseases [5]. ...
Article
Full-text available
There is a wide variance in the magnitude of physiological adaptations after resistance or endurance training. The incidence of “non” or “poor” responders to training has been reported to represent as high as 40% of the project’s sample. However, the incidence of poor responders to training can be ameliorated with manipulation of either the training frequency, intensity, type and duration. Additionally, global non-response to cardio-respiratory fitness training is eliminated when evaluating several health measures beyond just the target variables as at least one or more measure improves. More research is required to determine if altering resistance training variables results in a more favourable response in individuals with an initial poor response to resistance training. Moreover, we recommend abandoning the term “poor” responders, as ultimately the magnitude of change in cardiorespiratory fitness in response to endurance training is similar in “poor” and “high” responders if the training frequency is subsequently increased. Therefore, we propose “stubborn” responders as a more appropriate term. Future research should focus on developing viable physiological and lifestyle screening tests that identify likely stubborn responders to conventional exercise training guidelines before the individual engages with training. Exerkines, DNA damage, metabolomic responses in blood, saliva and breath, gene sequence, gene expression and epigenetics are candidate biomarkers that warrant investigation into their relationship with trainability. Crucially, viable biomarker screening tests should show good construct validity to distinguish between different exercise loads, and possess excellent sensitivity and reliability. Furthermore “red flag” tests of likely poor responders to training should be practical to assess in clinical settings and be affordable and non-invasive. Early identification of stubborn responders would enable optimization of training programs from the onset of training to maintain exercise motivation and optimize the impact on training adaptations and health.
... However, a meta-analysis conducted by Milanović et al 34 that included 723 participants demonstrated that while both endurance and HIT training improved V O 2max compared with no exercise, HIT training elicited larger improvements (5.5±1.2 mL/kg/min) compared with traditional endurance training (4.9±1.4 mL/kg/min). Moreover, the progression of training intensity also requires considerations. ...
Article
Full-text available
Physical activity (PA) guidelines for the general population are designed to mitigate the rise of chronic and debilitating diseases brought by inactivity and sedentariness. Although essential, they are insufficient as rates of cardiovascular, pulmonary, renal, metabolic and other devastating and lifelong diseases remain on the rise. This systemic failure supports the need for an improved exercise prescription approach that targets the individual. Significant interindividual variability of cardiorespiratory fitness (CRF) responses to exercise are partly explained by biological and methodological factors, and the modulation of exercise volume and intensity seem to be key in improving prescription guidelines. The use of physiological thresholds, such as lactate, ventilation, as well as critical power, have demonstrated excellent results to improve CRF in those struggling to respond to the current homogenous prescription of exercise. However, assessing physiological thresholds requires laboratory resources and expertise and is incompatible for a general population approach. A case must be made that balances the effectiveness of an exercise programme to improve CRF and accessibility of resources. A population-wide approach of exercise prescription guidelines should include free and accessible self-assessed threshold tools, such as rate of perceived exertion, where the homeostatic perturbation induced by exercise reflects physiological thresholds. The present critical review outlines factors for individuals exercise prescription and proposes a new theoretical hierarchal framework to help shape PA guidelines based on accessibility and effectiveness as part of a personalised exercise prescription that targets the individual.
... Previous studies conducted with children and adolescents outside the school setting found similar or slightly lower improvements of aerobic endurance capacity when running-based HIIT protocols had been used [23,34,[44][45][46]. A systematic review on the effectiveness of running-based HIIT sessions reported volatile performance improvements ranging from 2% to 43% in young adults, depending on the initial fitness level of participants and the duration and design of the intervention [21,34,47]. Beneficial effects of HIIT sessions in comparison to volume-oriented endurance training methods seem likely, especially when longer interventions and intervals and a greater work-rest ratio are used. ...
Article
Full-text available
High-Intensity Interval Training (HIIT) promises high training effects on aerobic fitness in children, adolescents and adults in a relatively short time. It is therefore well-established in professional training settings. HIIT methods could also be suited to Physical Education (P.E.) lessons and contribute to students’ health and fitness. Since HIIT sessions need little time and equipment, they can be efficiently implemented in P.E. However, there are few studies which have examined non-running-based HIIT programs in the school sport setting. We therefore conducted an intervention study including 121 students aged 11–15 attending a secondary school in Baden Württemberg, Germany. The effects of three different forms of HIIT training varying in duration and content (4 × 4 HIIT, 12 × 1 HIIT, CIRCUIT) were analyzed. The training was conducted twice a week over 6 weeks (10–12 sessions). Strength and endurance performances were determined in pre- and posttests prior to and after the intervention. Results verified that all three HIIT programs led to significant improvements in aerobic fitness (p < 0.001; part ŋ2 = 0.549) with no significant interaction between time x group. In contrast to the running-based HIIT sessions, CIRCUIT training also led to significant improvements in all of the measured strength parameters. Retrospectively, students were asked to assess their perception of the training intervention. The HIIT sessions were well-suited to students who considered themselves as “athletic”. Less athletic students found it difficult to reach the necessary intensity levels. The evaluation showed that endurance training conducted in P.E. lessons needs a variety of different contents in order to sufficiently motivate students. Students perceiving themselves as “unathletic” may need additional support to reach the required intensities of HIIT. Circuit training sessions using whole-body drills can be efficiently implemented in the P.E. setting and contribute to students’ health and fitness.
... The positive effect of aerobic training alone on brain health has been reported by several meta-analytic investigations indicating that aerobic training improves cognitive performance, including global and specific cognitive functioning in non-demented older adults (Smith et al., 2010;Barha et al., 2017;Bouaziz et al., 2017;Northey et al., 2018) as well as in patients with mild cognitive impairment (Zheng et al., 2016) and dementia (Groot et al., 2016). Moreover, it is well established that aerobic exercise elicits large improvements in physical capacity, estimated as peak oxygen uptake, in young (Milanović et al., 2015) and older adults (Bouaziz et al., 2020). Remarkably, a meta-analysis suggested that exercise programs with a short exercise duration (≤30 min) and a frequency of at least three sessions per week elicited beneficial effects on cognitive performance in older people with and without cognitive impairment (Sanders et al., 2019). ...
Article
Full-text available
Background: It was recently shown that intermittent hypoxic-hyperoxic exposure (IHHE) applied prior to a multimodal training program promoted additional improvements in cognitive and physical performance in geriatric patients compared to physical training only. However, there is a gap in the literature to which extent the addition of IHHE can enhance the effects of an aerobic training. Therefore, the aim of this study was to investigate the efficacy of IHHE applied prior to aerobic cycling exercise on cognitive and physical performance in geriatric patients. Methods: In a randomized, two-armed, controlled, and single-blinded trial, 25 geriatric patients (77–94 years) were assigned to two groups: intervention group (IG) and sham control group (CG). Both groups completed 6 weeks of aerobic training using a motorized cycle ergometer, three times a week for 20 min per day. The IG was additionally exposed to intermittent hypoxic and hyperoxic periods for 30 min prior to exercise. The CG followed the similar procedure breathing sham hypoxia and hyperoxia (i.e., normoxia). Within 1 week before and after the interventions, cognitive performance was assessed with the Dementia-Detection Test (DemTect) and the Clock Drawing Test (CDT), while physical performance was measured using the Timed “Up and Go” Test (TUG) and the Short-Physical-Performance-Battery (SPPB). Results: No interaction effect was found with respect to the DemTect ( η p 2 = 0.02). An interaction effect with medium effect size ( η p 2 = 0.08) was found for CDT performance with a higher change over time for IG ( d = 0.57) compared to CG ( d = 0.05). The ANCOVA with baseline-adjustment indicated between-group differences with a large and medium effect size at post-test for the TUG ( η p 2 = 0.29) and SPPB ( η p 2 = 0.06) performance, respectively, in favour of the IG. Within-group post-hoc analysis showed that the TUG performance was worsened in the CG ( d = 0.65) and remained unchanged in the IG ( d = 0.19). Furthermore, SPPB performance was increased ( d = 0.58) in IG, but no relevant change over time was found for CG ( d = 0.00). Conclusion: The current study suggests that an additional IHHE prior to aerobic cycling exercise seems to be more effective to increase global cognitive functions as well as physical performance and to preserve functional mobility in geriatric patients in comparison to aerobic exercise alone after a 6-week intervention period.
... [137][138][139] However, the status of PAE is being challenged by HIIT. For instance, studies reported that, both in young and old people, HIIT was more effective than MssssICT in enhancing vascular function 133 and improving cardiorespiratory capacity; [140][141][142][143] oxidative stress of the myocardium after myocardial infarction can be better attenuated by HIIT than MICT; 144 and compared with MICT, HIIT displayed similar or greater impacts on reduction of adiposity, 65,145 increase in insulin sensitivity in obese people, 146 reduction of blood triglycerides (TGs) and glucose levels in older individuals, 138,147 and enhancement of immune system with significant reduction of the time commitment. 148 At the same time, both HIIT and MICT displayed similarly high rate of completion and attendance, and low rate of adverse events in patients with CVD. ...
Article
Full-text available
Sarcopenia, an age-related disease characterized by loss of muscle strength and muscle mass, has attracted the attention of medical experts due to its severe morbidity, low living quality, high expenditure of health care, and mortality. Traditionally, persistent aerobic exercise (PAE) is considered as a valid way to attenuate muscular atrophy. However, nowadays, high intensity interval training (HIIT) has emerged as a more effective and time-efficient method to replace traditional exercise modes. HIIT displays comprehensive effects on exercise capacity and skeletal muscle metabolism, and it provides a time-out for the recovery of cardiopulmonary and muscular functions without causing severe adverse effects. Studies demonstrated that compared with PAE, HIIT showed similar or even higher effects in improving muscle strength, enhancing physical performances and increasing muscle mass of elder people. Therefore, HIIT might become a promising way to cope with the age-related loss of muscle mass and muscle function. However, it is worth mentioning that no study of HIIT was conducted directly on sarcopenia patients, which is attributed to the suspicious of safety and validity. In this review, we will assess the effects of different training parameters on muscle and sarcopenia, summarize previous papers which compared the effects of HIIT and PAE in improving muscle quality and function, and evaluate the potential of HIIT to replace the status of PAE in treating old people with muscle atrophy and low modality; and point out drawbacks of temporary experiments. Our aim is to discuss the feasibility of HIIT to treat sarcopenia and provide a reference for clinical scientists who want to utilize HIIT as a new way to cope with sarcopenia.
Article
Introduction High-intensity interval training (HIIT) is an efficient training method to improve vascular function, maximal oxygen consumption, and muscle mitochondrial capacity while maximizing muscular damage. Recently, functional foods have been considered a practical approach to avoiding HIIT damage and improving sports performance. Thus, the present study will evaluate the effectiveness of date seed powder as a functional food on the nutritional, oxidative stress, anti/inflammatory status, mental health, and performance of active people. Methods This study is a double-blind, randomized, placebo-controlled trial, which will be conducted among recreational runners at Tabriz stadiums, Iran. Thirty-six recreational runners will be randomly selected into two groups to consume 26g/d date seed powder or placebo for 14 days. Both groups will do HIIT workouts. Body composition, food intake, total antioxidant capacity (TAC), oxidative stress index (OSI), total oxidant status (TOS), superoxide dismutase (SOD), glutathione peroxidase (GPx), malondialdehyde (MDA), 8-iso-prostaglandin F2α (8-iso-PGF2α), uric acid, protein carbonyl (PC), catalase (CAT), glutathione (GSH), nitric oxide (NO), high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), IL-6/IL-10, creatine kinase (CK), lactate dehydrogenase (LDH), myoglobin (MYO), brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), irisin, cortisol, muscle pain, aerobic and anaerobic performance will be evaluated at the beginning, end of the intervention and 24 h later. Ethics and dissemination This study was approved by the Medical Ethics Committee of TBZMED (No.IR.TBZMED.REC.1399.1011). This research's findings will be published in a peer-reviewed journal and presented at international conferences. Trial registration Iranian Registry of Clinical Trials website (www.IRCT.ir/, IRCT20150205020965N9).
Article
Full-text available
Systematic reviews should build on a protocol that describes the rationale, hypothesis, and planned methods of the review; few reviews report whether a protocol exists. Detailed, well-described protocols can facilitate the understanding and appraisal of the review methods, as well as the detection of modifications to methods and selective reporting in completed reviews. We describe the development of a reporting guideline, the Preferred Reporting Items for Systematic reviews and Meta-Analyses for Protocols 2015 (PRISMA-P 2015). PRISMA-P consists of a 17-item checklist intended to facilitate the preparation and reporting of a robust protocol for the systematic review. Funders and those commissioning reviews might consider mandating the use of the checklist to facilitate the submission of relevant protocol information in funding applications. Similarly, peer reviewers and editors can use the guidance to gauge the completeness and transparency of a systematic review protocol submitted for publication in a journal or other medium.
Article
Full-text available
Systematic reviews and meta-analyses have become increasingly important in health care. Clinicians read them to keep up to date with their field [1],[2], and they are often used as a starting point for developing clinical practice guidelines. Granting agencies may require a systematic review to ensure there is justification for further research [3], and some health care journals are moving in this direction [4]. As with all research, the value of a systematic review depends on what was done, what was found, and the clarity of reporting. As with other publications, the reporting quality of systematic reviews varies, limiting readers' ability to assess the strengths and weaknesses of those reviews. Several early studies evaluated the quality of review reports. In 1987, Mulrow examined 50 review articles published in four leading medical journals in 1985 and 1986 and found that none met all eight explicit scientific criteria, such as a quality assessment of included studies [5]. In 1987, Sacks and colleagues [6] evaluated the adequacy of reporting of 83 meta-analyses on 23 characteristics in six domains. Reporting was generally poor; between one and 14 characteristics were adequately reported (mean = 7.7; standard deviation = 2.7). A 1996 update of this study found little improvement [7]. In 1996, to address the suboptimal reporting of meta-analyses, an international group developed a guidance called the QUOROM Statement (QUality Of Reporting Of Meta-analyses), which focused on the reporting of meta-analyses of randomized controlled trials [8]. In this article, we summarize a revision of these guidelines, renamed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses), which have been updated to address several conceptual and practical advances in the science of systematic reviews (Box 1). Box 1: Conceptual Issues in the Evolution from QUOROM to PRISMA Completing a Systematic Review Is an Iterative Process The conduct of a systematic review depends heavily on the scope and quality of included studies: thus systematic reviewers may need to modify their original review protocol during its conduct. Any systematic review reporting guideline should recommend that such changes can be reported and explained without suggesting that they are inappropriate. The PRISMA Statement (Items 5, 11, 16, and 23) acknowledges this iterative process. Aside from Cochrane reviews, all of which should have a protocol, only about 10% of systematic reviewers report working from a protocol [22]. Without a protocol that is publicly accessible, it is difficult to judge between appropriate and inappropriate modifications.
Article
Full-text available
Systematic reviews and meta-analyses are essential to summarize evidence relating to efficacy and safety of health care interventions accurately and reliably. The clarity and transparency of these reports, however, is not optimal. Poor reporting of systematic reviews diminishes their value to clinicians, policy makers, and other users.Since the development of the QUOROM (QUality Of Reporting Of Meta-analysis) Statement--a reporting guideline published in 1999--there have been several conceptual, methodological, and practical advances regarding the conduct and reporting of systematic reviews and meta-analyses. Also, reviews of published systematic reviews have found that key information about these studies is often poorly reported. Realizing these issues, an international group that included experienced authors and methodologists developed PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) as an evolution of the original QUOROM guideline for systematic reviews and meta-analyses of evaluations of health care interventions.The PRISMA Statement consists of a 27-item checklist and a four-phase flow diagram. The checklist includes items deemed essential for transparent reporting of a systematic review. In this Explanation and Elaboration document, we explain the meaning and rationale for each checklist item. For each item, we include an example of good reporting and, where possible, references to relevant empirical studies and methodological literature. The PRISMA Statement, this document, and the associated Web site (http://www.prisma-statement.org/) should be helpful resources to improve reporting of systematic reviews and meta-analyses.
Article
Full-text available
While the physiological adaptations that occur following endurance training in previously sedentary and recreationally active individuals are relatively well understood, the adaptations to training in already highly trained endurance athletes remain unclear. While significant improvements in endurance performance and corresponding physiological markers are evident following submaximal endurance training in sedentary and recreationally active groups, an additional increase in submaximal training (i.e. volume) in highly trained individuals does not appear to further enhance either endurance performance or associated physiological variables [e.g. peak oxygen uptake (V̇O2peak), oxidative enzyme activity]. It seems that, for athletes who are already trained, improvements in endurance performance can be achieved only through high-intensity interval training (HIT). The limited research which has examined changes in muscle enzyme activity in highly trained athletes, following HIT, has revealed no change in oxidative or glycolytic enzyme activity, despite significant improvements in endurance performance (p 2max is achieved (Vmax) as the interval intensity, and fractions (50 to 75%) of the time to exhaustion at Vmax (Tmax) as the interval duration has been successful in eliciting improvements in performance in long-distance runners. However, Vmax and Tmax have not been used with cyclists. Instead, HIT programme optimisation research in cyclists has revealed that repeated supramaximal sprinting may be equally effective as more traditional HIT programmes for eliciting improvements in endurance performance. Further examination of the biochemical and physiological adaptations which accompany different HIT programmes, as well as investigation into the optimal HIT programme for eliciting performance enhancements in highly trained athletes is required.
Article
Full-text available
There is a demand for effective training methods that encourage exercise adherence during advancing age, particularly in sedentary populations. This study examined the effects of high-intensity interval training (HIIT) exercise on health-related quality of life (HRQL), aerobic fitness and motivation to exercise in ageing men. Participants consisted of males who were either lifelong sedentary (SED; N = 25; age 63 ± 5 years) or lifelong exercisers (LEX; N = 19; aged 61 ± 5 years). [Formula: see text] and HRQL were measured at three phases: baseline (Phase A), week seven (Phase B) and week 13 (Phase C). Motivation to exercise was measured at baseline and week 13. [Formula: see text] was significantly higher in LEX (39.2 ± 5.6 ml kg min(-1)) compared to SED (27.2 ± 5.2 ml kg min(-1)) and increased in both groups from Phase A to C (SED 4.6 ± 3.2 ml kg min(-1), 95 % CI 3.1 - 6.0; LEX 4.9 ± 3.4 ml kg min(-1), 95 % CI 3.1-6.6) Physical functioning (97 ± 4 LEX; 93 ± 7 SED) and general health (70 ± 11 LEX; 78 ± 11 SED) were significantly higher in LEX but increased only in the SED group from Phase A to C (physical functioning 17 ± 18, 95 % CI 9-26, general health 14 ± 14, 95 % CI 8-21). Exercise motives related to social recognition (2.4 ± 1.2 LEX; 1.5 ± 1.0 SED), affiliation (2.7 ± 1.0 LEX; 1.6 ± 1.2 SED) and competition (3.3 ± 1.3 LEX; 2.2 ± 1.1) were significantly higher in LEX yet weight management motives were significantly higher in SED (2.9 ± 1.1 LEX; 4.3 ± 0.5 SED). The study provides preliminary evidence that low-volume HIIT increases perceptions of HRQL, exercise motives and aerobic capacity in older adults, to varying degrees, in both SED and LEX groups.
Article
Objective To determine the effects of resistance training combined with either moderate-intensity endurance (MICT) or low-volume high-intensity interval (HIIT) training on cardiovascular risk profiles in patients with coronary artery disease. Design Factorial repeated-measures study design. Methods Nineteen patients were randomized into MICT (n = 10) or HIIT (n = 9), and attended 2 supervised exercise sessions a week for 6-months. The first 3-months involved exclusive MICT or HIIT, after which progressive resistance training was added to both groups for the remaining 3-months. Fitness (VO2peak), blood pressure and heart rate, lipid profiles and health related quality of life assessments were performed at pretraining, 3 and 6-months training. Results VO2peak increased from pretraining to 3-months in both groups (MICT: 19.8 ± 7.3 vs. 23.2 ± 7.4 ml·kg−1·min−1; HIIT: 21.1 ± 3.3 vs. 26.4 ± 5.2 ml·kg−1·min−1, p < 0.001) with no further increase at 6-months. Self-evaluated health and high-density lipoprotein were increased following 6-months of MICT, while all remaining indices were unchanged. Low-volume HIIT did not elicit improvements in lipids or health related quality of life. Blood pressures and heart rates were unchanged with training in both groups. Conclusions Findings from our pilot study suggest improvements in fitness occur within the first few months of training in patients with coronary artery disease, after which the addition of resistance training to MICT and HIIT elicited no further improvements. Given the importance of resistance training in cardiac rehabilitation, additional research is required to determine its effectiveness when combined with HIIT.