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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Date results information initially provided
Type of registration
Retrospectively registered

Titles & IDs
Public title
High-intensity interval training for health and fitness in males with overweight or obesity.
Scientific title
High-intensity interval training for health and fitness in males with overweight or obesity.
Secondary ID [1] 299363 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
obesity 314518 0
overweight 314519 0
Condition category
Condition code
Metabolic and Endocrine 312865 312865 0 0
Metabolic disorders
Diet and Nutrition 312932 312932 0 0

Study type
Description of intervention(s) / exposure
High-intensity interval training (HIIT)
- randomized trial with moderate-intensity continuous training (MICT) acting as the comparator group to HIIT. Participants were randomly assigned (1:1) to a HIIT or MICT training group.
- Exercise training sessions conducted over 6 weeks x 3 sessions per week.
- all training conducted at a single site (university exercise research lab) where both groups trained in parallel.

HIIT protocol details:
Participants trained 3 times per week for 6 weeks. A minimum of 24 hours between training sessions was required and no more than two consecutive days of training. All training was conducted on manual-resistance cycle ergometers (Monark 828E Sweden) or electronically-braked cycle ergometers (Monark 928E; for HIIT participants only due to its ability to pre-programme interval training sessions). All sessions were supervised by trained research assistants (undergraduate Exercise Physiology students). Heart rate (HR) and rating of perceived exertion (RPE) were monitored throughout every training session using a Polar T34 heart rate monitor and unmodified (6-20) Borg scale 20 respectively. For HIIT participants, HR and RPE were recorded at the end of every 2nd interval and recovery period.
HIIT sessions consisted of 10 × 1-minute intervals at 90-100% Wmax (approximating ~90% HRmax; RPE ~15), interspersed with 1 minute of active recovery at 15% Wmax. The intensity of training was progressively increased over the 6-week intervention (weeks 1 and 2: 90% Wmax; weeks 3 and 4: 95% Wmax; weeks 5 and 6: 100% Wmax). Each session began with a 3-minute warm-up at 35% Wmax (approximating 65% HRmax) and ended with a 2-minute cool down at 15% Wmax. Total exercising time for each session was 24 minutes for the HIIT group.

Adherence was assessed by number of sessions attended. Compliance was assessed by monitoring HR in relation to desired HR target range for each session. Safety was assessed by reports of adverse events during or within 4 hours following each session.
Intervention code [1] 315627 0
Treatment: Other
Intervention code [2] 315666 0
Comparator / control treatment
Moderate-intensity continuous training (MICT)
MICT sessions consisted of 30 minutes of continuous exercise at 65-75% HRmax (approximating RPE ~11). The intensity of training was progressively increased over the 6-week intervention (weeks 1 and 2: 65% HRmax; weeks 3 and 4: 70% HRmax; weeks 5 and 6: 75% HRmax). Workloads were continually adjusted in each training session to maintain the desired HR (range: 35-50% Wmax). Total exercising time for each session was 30 minutes for the MICT group. For MICT participants, HR and RPE were recorded every 5 minutes.
Control group

Primary outcome [1] 321470 0
Maximal aerobic capacity
Maximal aerobic capacity (VO2max) was assessed by graded maximal exercise test on an electronically-braked cycle ergometer (Ergoline) under the supervision of an accredited exercise scientist. Gas exchange was analysed continuously during the exercise test by a metabolic cart consisting of a computerized, on-line, open-circuit indirect calorimetry system (Medgraphics Ultima CPX, Minnesota, USA). The O2 and CO2 sensors were calibrated before each exercise session using reference gases. Participants were fitted with a face mask supporting a pneumotach to enable the gas exchange measures. The test commenced at 50W for the first 4 minutes and then increased by 10W every 30 seconds until volitional exhaustion. HR and RPE were recorded at every stage. The test was terminated when the pedalling rate fell below 20 revolutions per minute. Participants were verbally encouraged to go to volitional exhaustion. Peak oxygen consumption (VO2max) was calculated as the highest recorded value, using data of the recorded rolling average of 15-second epochs. HRmax and peak power output (Wmax) were also recorded. Peak power output (Wmax, defined as the last completed workload before volitional fatigue) and HRmax were also recorded and used as the basis for determining the intensity of the HIIT and MICT sessions for each participant.
Timepoint [1] 321470 0
Pre-training (2-5 days prior to first training session) vs post-training (within 2-5 days post-final training session)
Primary outcome [2] 321471 0
Body fat (kg)
Whole body composition was measured using dual energy x-ray absorptiometry (Lunar iDXA, GE Medical Systems, Wisconsin). Participants were tested following an overnight fast. Measures of fat mass (FM; kg), lean mass (LM; kg) and percent body fat (%BF; %) were recorded for whole body and for distinct anatomical regions (trunk, android, gynoid, legs, arms, visceral). Participants were tested after removing all metals and jewelry. Participants were positioned in the center of the platform, supine, with arms by their side, and were instructed to remain still and breathe normally for the duration of the 7-minute scan. Data was recorded using standard DXA software (enCORE version15). The DXA machine was calibrated prior to each day of testing.
Bodyweight was measured using medical scales (Charder MS4600), and height was measured using a portable stadiometer. BMI was calculated as body weight (kg) divided by height in meters squared (m2). Waist circumference was measured in the horizontal plane midway between the lowest palpable rib and the top of the iliac crest.
Timepoint [2] 321471 0
Pre-training (2-5 days prior to first training session) vs post-training (within 2-5 days post-final training session)
Primary outcome [3] 321472 0
Blood pressure (composite outcome - systolic and diastolic; aortic and brachial)
Participants were tested using applanation tonometry (SphygmoCor XCel, AtCor Medical, Sydney, Australia) using protocols as stipulated by expert consensus guidelines 19. Participants were tested in the supine position after 10 minutes lying rest. Pulse wave analysis using an upper-arm cuff was applied to assess peripheral (brachial) and central (aortic) measures of BP. Resting brachial blood pressure was derived from brachial artery waveforms from the right upper arm. From the pulse pressure recorded at the peripheral site, a corresponding aortic pressure waveform was generated via a proprietary digital signal processing and transfer function to then derive indices of central BP (at the aorta).
Timepoint [3] 321472 0
Pre-training (2-5 days prior to first training session) vs post-training (within 2-5 days post-final training session)
Secondary outcome [1] 375064 0
The 20-item Positive and Negative Affect Schedule (PANAS) was used to assess positive and negative affect at baseline and post-training. Participants were assessed at an initial baseline assessment and a post-training assessment, with each assessment conducted in the morning. The post-training assessment was conducted between 2-5 days of the final training session.
Timepoint [1] 375064 0
Pre-training (2-5 days prior to first training session) vs post-training (within 2-5 days post-final training session)
Secondary outcome [2] 375263 0
Pressure pain threshold
Pressure pain thresholds (PPTs) were assessed over three different muscles: the rectus femoris (halfway between the inguinal fold and superior aspect of the patella), the tibialis anterior (lateral to the mid-tibia) and the trapezius (upper aspect). The 1cm2 rubber-tipped probe of a handheld algometer (Wagner FDX-50, Greenwich, CT, USA) was applied perpendicularly over the muscle belly and the force was increased at a rate of approximately 1kg/s. As the pressure changed from ‘discomfort’ to ‘pain’, participants were instructed to say ‘stop’ to indicate their PPT. PPTs were assessed three times over each muscle in a rotational order and PPT was calculated as the average of the three measurements at each location. All measurements were made on the right side of the body. Before the test measurements were taken, a practice run was performed on the left trapezius muscle to familiarise participants with the procedure.
Timepoint [2] 375263 0
Pre-training (2-5 days prior to first training session) vs post-training (within 2-5 days post-final training session)

Key inclusion criteria
Males aged 18-45, BMI 25-35 kg/m2, physically inactive
Minimum age
18 Years
Maximum age
45 Years
Can healthy volunteers participate?
Key exclusion criteria
diagnosed cardiovascular risk factors such as hypertension, diabetes or hyperlipidaemia; previous history of cardiovascular disease; or any uncontrolled medical disorder

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation is not concealed
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Participants were randomly allocated into a training group (1:1) after the initial assessment using a pre-generated list of equally-distributed permuted blocks ( Blinding of participants to their assigned training group was not possible, and assessors also were not blinded to the participant’s training group.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
All outcomes except PPT
All analyses were performed using SPSS v24.0 (SPSS Inc., Chicago, IL). Equality of variance was assessed using Levene’s test and the normality of the data was assessed using the Shapiro-Wilk statistic. General linear model repeated measures ANOVA (2 groups × 2 time-points) was applied for assessment measures (or Friedman’s test applied for non-normally distributed data). Group comparisons for baseline characteristics [HIIT vs MICT] were made with independent samples t-tests, and within-group changes after training were analysed using paired t-tests (or Wilcoxon signed ranks tests for non-normally distributed data). Statistical significance was set at p < 0.05. Effect sizes for the pairwise comparisons were calculated using Cohen’s d (Cohen 1988) (or Z/v(Npre+Npost) for non-normally distributed variables), with the magnitude of effect sizes determined as: small effect = 0.20–0.49, medium effect = 0.50–0.79 and large effect = 0.80. Pearson’s correlation (r) was applied to examine the relationship between baseline characteristics and the magnitude of training effect across measures. Data is presented as mean ± SD for normally-distributed data and median (interquartile range) for non-normally distributed data.
PPT data
Data was analyzed using the IBM Statistical Package for Social Sciences (version 24, Chicago, IL, USA). Equality of variance was assessed using Levene’s test and the normality of the data was assessed using visual inspection and the Shapiro-Wilk statistic. Two-tailed non-parametric inferential statistics were used for data that were not normally distributed. Mann-Whitney U tests were used to examine between group differences in baseline PPTs and PPT change scores after exercise. Exact sign tests were used to examine within group changes in PPT after exercise. Friedman’s test was used to examine within group changes over time (i.e. initial assessment and exercise sessions 1, 9 and 18) in baseline PPTs and the magnitude of EIH. To enable comparisons between and within groups, effect sizes (r) were also calculated by dividing the z-value of the relevant test by the square root of the number of observations. When necessary, effect sizes were direction adjusted so that an increase in PPT after exercise was signified by a positive effect size. Effect sizes were interpreted as small (0.1), moderate (0.3) or large (0.5) (Cohen 1988). Statistical significance for alpha was set at 0.05 and p-values were multiplied by the number of comparisons made (Bonferroni correction) for each test. Unless otherwise stated, data are presented as mean ranks and are described in terms of the effect size (r) of the change.

The sample size calculation for the entire study was based on detecting a difference in the change in the primary outcome (VO2max) between the HIIT and MICT groups. Separate sample size calculations were not conducted for each of the secondary outcomes (e.g. body composition, vascular function and PPT). However, we performed an a posteriori calculation using our sample sizes to show what size effect was required to detect a difference in the change in PPT between the HIIT and MICT groups after chronic training. We calculated an effect size (Cohen’s d) of 1.14 was required to detect a difference between the groups for a change in PPT after chronic training, using a two-tailed t-test (Means: Wilcoxon-Mann-Whitney test (two groups)) with an alpha of 0.05, power of 0.80 and sample sizes of 16 and 12 in groups one and two, respectively. This calculation was performed in G*Power (version, Dusseldorf, Germany) (Faul et al., 2007).

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 303879 0
Self funded/Unfunded
Name [1] 303879 0
Address [1] 303879 0
Country [1] 303879 0
Primary sponsor type
University of New South Wales
School of Medical Sciences
Wallace Wurth building
Randwick, Sydney 2052
Secondary sponsor category [1] 304079 0
Name [1] 304079 0
Address [1] 304079 0
Country [1] 304079 0

Ethics approval
Ethics application status
Ethics committee name [1] 304385 0
UNSW Human Research Ethics Committee
Ethics committee address [1] 304385 0
UNSW Research Ethics & Compliance Support
The University of New South Wales
Sydney NSW 2052 Australia
Ethics committee country [1] 304385 0
Date submitted for ethics approval [1] 304385 0
Approval date [1] 304385 0
Ethics approval number [1] 304385 0
HREC #: HC16432

Brief summary
We compared the effectiveness of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on a range of health and fitness measures in males with overweight or obesity. Participants completed 6 weeks x 3 sessions per week training, randomised to either group. We hypothesised that HIIT and MICT would increase aerobic fitness, reduce body fat, blood pressure and pressure pain sensitivity, and improve mood state after 6 weeks of training, with greater effectiveness following HIIT compared to MICT.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 96770 0
Dr Andrew Keech
Address 96770 0
University of New South Wales
School of Medical Sciences
Wallace Wurth building
Randwick, Sydney 2052
Country 96770 0
Phone 96770 0
+61 2 9385 8331
Fax 96770 0
Email 96770 0
Contact person for public queries
Name 96771 0
Dr Andrew Keech
Address 96771 0
University of New South Wales
School of Medical Sciences
Wallace Wurth building
Randwick, Sydney 2052
Country 96771 0
Phone 96771 0
+61 2 9385 8331
Fax 96771 0
Email 96771 0
Contact person for scientific queries
Name 96772 0
Dr Andrew Keech
Address 96772 0
University of New South Wales
School of Medical Sciences
Wallace Wurth building
Randwick, Sydney 2052
Country 96772 0
Phone 96772 0
+61 2 9385 8331
Fax 96772 0
Email 96772 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
What data in particular will be shared?
Deidentified assessment outcomes
When will data be available (start and end dates)?
Start: Immediately
End-date: no end date determined
Available to whom?
Available for what types of analyses?
Any purpose
How or where can data be obtained?
Upon request - email the investigator (
What supporting documents are/will be available?
No other documents available
Summary results
Have study results been published in a peer-reviewed journal?
Journal publication details
Publication date and citation/details [1] 4999 0
Hakansson, S., Jones, M.D., Ristov, M., et al. Intensity-dependent effects of aerobic training on pressure pain threshold in overweight men: A randomized trial. European Journal of Pain 22, 1813-1823 (2018).
Attachments [1] 4999 0
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary