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Trial registered on ANZCTR


Registration number
ACTRN12623001093673p
Ethics application status
Submitted, not yet approved
Date submitted
21/09/2023
Date registered
18/10/2023
Date last updated
18/10/2023
Date data sharing statement initially provided
18/10/2023
Type of registration
Prospectively registered

Titles & IDs
Public title
Effects of high intensity interval training in hypoxia on insulin sensitivity in overweight and sedentary individual
Scientific title
Effects of high intensity interval training in hypoxia on insulin sensitivity in overweight and sedentary individual.
Secondary ID [1] 309646 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Insulin resistance 329974 0
Physical Inactivity 329975 0
Overweight 329976 0
Obesity 329977 0
Condition category
Condition code
Metabolic and Endocrine 326886 326886 0 0
Metabolic disorders
Diet and Nutrition 328400 328400 0 0
Obesity

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Potential participants will be initially screened by the primary investigator. Participants who meet the eligibility criteria will then be invited to the Exercise Physiology Lab at Murdoch University. Written informed consent will be obtained from all participants prior to participation. Baseline assessments including anthropometric measurements, physiological parameters, and metabolic status will be undertaken before the start of the exercise training program. This study will adopt a 10-week Randomised Controlled Trial design; participants will be allocated to a 10-week training program that will either be performed in normal ambient conditions (normoxia) or in low oxygen conditions (i.e., hypoxia).

Procedure:
All participants will be required to complete a 10-week training program. Specifically, participants will complete three supervised exercise training session per week, at the Strength and Conditioning Laboratory in Murdoch University. Each training session will consist of both an aerobic and resistant exercise component, with an approximate session duration of 60-75 min. All participants will undergo a standardised training for the first 2 weeks. After the 2 weeks of standardised training, participants will be allocated to either a group that performs the aerobic exercise in hypoxia or the group that performs the aerobic session in normoxia. The resistance exercise will always be conducted in normal ambient conditions. All training sessions will be supervised by an exercise physiologist.

Exercise adherence will be assessed for all participants in the research by the exercise physiologist conducting the training sessions. The total number of sessions completed, as well as workload (during the interval training) and the number of repetitions and weight lifted (during the resistance training), will be recorded to determine adherence to the program.

Standardized training (First 2 weeks)
During each session, participants will first perform 20 min of high intensity interval cycling which will consist of four, 1-min cycling bouts interspersed with 4 min of recovery. Specifically, participants will perform the work and recovery bouts at a perceptually regulated intensity corresponding to a RPE of 16 (between 'hard' and 'very hard'; 6-20 Borg scale) and 10 ('very light' and 'fairly light'), respectively. Following 10 min of rest, participants will then perform four different resistance exercise involving the major muscle groups (i.e., leg press, bench press, lateral pulldown and overhead press). The weights will be individually adjusted to ensure that participants achieve 12-15 repetitions for each set. All participants will perform 3 sets of each resistance exercise, with 60 s of rest between sets.

Hypoxia screening (Prior to hypoxia training)
Upon completion of the 2-week standardized training, participants will then be randomly allocated into either the exercise with hypoxia (Ex+H) or exercise without hypoxia (Ex) group for the final 8 weeks.

Prior to the hypoxia training, all participants (allocated to hypoxia training group) will be required to undergo a hypoxia screening test. Participants will be fitted with a facemask connected via corrugated plastic tubing to a portable hypoxic generator under passive resting conditions. Participants will first be exposed to a hypoxic dose of FiO2 ~0.18 (equivalent to ~1200m) for 5 min. The facemask will then be removed, so that participants will breathe normal air (i.e. FiO2 0.21). An identical procedure will be performed for a hypoxic dose of FiO2~0.16 and FiO2~014. Arterial oxygen saturation (SpO2) will be measured continuously (1Hz) via a pulse oximeter. It is expected that rapid re-oxygenation will occur immediately upon removal of the facemask i.e., within seconds, with recovery to baseline SpO2 (of 98-100%) within a minute.

Hypoxia training (Final 8 weeks)
The targeted FiO2 for the hypoxia training is 0.14 (i.e., ~3000m). However, to ensure that participants are accustomed to hypoxia, the FiO2 will be set at 0.18 during the first training session (in week 2) and gradually decreased to 0.14 by the end of week 4. Participants will only perform the interval training in hypoxia (i.e., four, 1-min cycling bouts interspersed with 4 min of recovery); Hypoxic exposure will be implemented throughout the entire high intensity interval exercise. All hypoxia training sessions will be conducted in an environmental chamber. All resistance training will be performed in normal ambient conditions.

For the final 4 weeks (week 7 to 10), participants will perform the same high intensity interval exercise with the exception that the total duration will be increased to 30 min (i.e., total of 6, 1-min cycling bouts, interspersed with 4 min of recovery).

The specificities of the resistance training will remain the same (as the first 2 weeks) during this 8 weeks of training, with the exception that the intensity will be progressively increased. Specifically, weights will be gradually increased to ensure that individuals achieve 12-15 repetitions (per set) during week 1-4 and 8-12 repetitions during week 5-10.

The training session from week 1 to 6 will take approximately 60 min (per session) whilst the final 4 weeks will take approximately 75 min.

Following the completion of the training program (i.e., week 10), participants will complete their post-intervention assessments, which will be identical with the baseline measurements, at least 24 h but not more than 96 h after the last training session.
Intervention code [1] 326074 0
Treatment: Other
Comparator / control treatment
Comparison will be made between the two conditions: Exercise in hypoxia vs. Exercise in normoxia. The Exercise in normoxia group will be used as the comparator in this study.
Control group
Active

Outcomes
Primary outcome [1] 334726 0
Changes in average blood glucose levels (glycated hemoglobin; HbA1c) assessed from blood samples.
Timepoint [1] 334726 0
Baseline and post-completion of the training (i.e. at least 24 h but not more than 96 h after the last training session)
Secondary outcome [1] 421872 0
Changes in fasting blood glucose levels assessed from blood samples
Timepoint [1] 421872 0
Baseline and post-completion of the training (i.e. at least 24 h but not more than 96 h after the last training session).
Secondary outcome [2] 421873 0
Changes in fasting blood insulin levels assessed from blood samples.
Timepoint [2] 421873 0
Baseline and post-completion of the training (i.e. at least 24 h but not more than 96 h after the last training session).
Secondary outcome [3] 421875 0
Change in Whole Body Composition assessed via a DXA Analysis
Timepoint [3] 421875 0
Baseline and post-completion of the training (i.e. at least 24 h but not more than 96 h after the last training session).
Secondary outcome [4] 421876 0
Change in Body weight (kg) assessed by a digital scale.
Timepoint [4] 421876 0
Baseline and post-completion of the training (i.e. at least 24 h but not more than 96 h after the last training session).
Secondary outcome [5] 421878 0
Changes in waist to hip ratio via measurements of hip and waist circumference (cm) with a tape measure.
Timepoint [5] 421878 0
Baseline and post-completion of the training (i.e. at least 24 h but not more than 96 h after the last training session).
Secondary outcome [6] 421882 0
Changes in peak oxygen consumption, assessed by an aerobic fitness test (VO2peak test) on an electro-magnetically braked cycle ergometer.
Timepoint [6] 421882 0
Baseline and post-completion of the training (i.e. at least 24 h but not more than 96 h after the last training session).
Secondary outcome [7] 426481 0
Changes in glucose area under the curve assessed during a 2-h oral glucose tolerance test
Timepoint [7] 426481 0
Baseline and post-completion of the training (i.e. at least 24 h but not more than 96 h after the last training session).
Secondary outcome [8] 426482 0
Changes in 1-RM muscular strength assessed by shoulder press exercise
Timepoint [8] 426482 0
Baseline and immediately post-completion of the training (i.e. last training session).
Secondary outcome [9] 427075 0
Changes in dietary intake assessed using a 24-h dietary recall.
Timepoint [9] 427075 0
Recorded on 3 non-consecutive days including 2 days on the weekend during the first (i.e., baseline; week 1 and 2) and last two weeks (i.e. completion; week 9 and 10) of training.
Secondary outcome [10] 427076 0
Changes in Metabolomics response to interval training (in hypoxia and normoxia) within and between groups assessed from finger-tip blood samples (assessed by LC-MS and NMR).
Timepoint [10] 427076 0
At baseline, week 1, 2, 4, 6, 8, and 10 (last training session of each week)
Secondary outcome [11] 427451 0
Changes in metabolomics profile within and between groups at baseline and post-completion of the training assessed from venous blood samples (assessed by LC-MS and NMR) during the 2-h oral glucose tolerance test.
Timepoint [11] 427451 0
At baseline and post completion of training (i.e. at least 24 h but not more than 96 h after the last training session).
Secondary outcome [12] 427482 0
Changes in 1-RM muscular strength assessed by leg press exercise
Timepoint [12] 427482 0
Baseline and immediately post-completion of the training (i.e. last training session)
Secondary outcome [13] 427484 0
Changes in 1-RM muscular strength assessed by lateral pulldown exercise
Timepoint [13] 427484 0
Baseline and immediately post-completion of the training (i.e. last training session)
Secondary outcome [14] 427486 0
Changes in 1-RM muscular strength assessed by chest press exercise
Timepoint [14] 427486 0
Baseline and immediately post-completion of the training (i.e. last training session)
Secondary outcome [15] 427492 0
Changes in appetite regulation using a visual analogue scale (VAS; 100 mm horizontal line) for four distinct components of appetite perception (hunger, fullness, desire to eat and prospective food consumption).
Timepoint [15] 427492 0
Baseline and immediately post completion of the training (i.e. at least 24 h but not more than 96 h after the last training session).

Eligibility
Key inclusion criteria
Age: 18-45 years old
BMI greater than or equal to 27kg/m2
Sedentary (defined as less than 2 scheduled exercise session and 15o min of physical activity per week)
Minimum age
18 Years
Maximum age
45 Years
Sex
Both males and females
Can healthy volunteers participate?
No
Key exclusion criteria
Currently taking insulin
Diagnosed with type 2 diabetes
History of heart condition
Uncontrolled hypertension (greater than 160/90 mmHg)
Contraindication to exercise
History of altitude related sickness
Individuals who are born and raised at 1500 m and/or had travelled to elevation 1000 m three months prior to the study

Study design
Purpose of the study
Treatment
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)
Permuted block randomisation generated by a randomisation software.
Randomisation will be stratified by sex, by generating 2 separate keys.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
The Hemoglobin A1c (HbA1c) measure will be used as the primary outcome for this study. Taking into consideration the type 1 error rate (0.05), minimum power (0.80) and expected change in HbA1c (~0.6%), a sample size of 24 would provide sufficient power (0.813). However, 30 participants will be recruited for this study to account for dropouts.

Values will be expressed as mean ± standard deviation. Treatment effects will be estimated using linear mixed models to assess for any changes over time (e.g. pre and post-intervention) between the two intervention groups (NOR and HYP). The group-time interaction will be modelled as fixed effects with a random intercept (to account for differences at baseline). The group-time interaction will be examined with pairwise comparisons of the estimated marginal means. Additionally, the main effects for time will also be examined using pairwise comparisons of the estimated marginal means. The magnitude of change for each outcome will be reported using Hedge’s g and interpreted as small (g = 0.2), moderate (g = 0.5) or large (g = 0.8). All statistical calculations will be performed using SPSS statistical software V.24.0 (IBM Corp., Armonk, NY, USA). The significance level will be set at p 0.05.

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
1/11/2023
Actual
Date of last participant enrolment
Anticipated
1/04/2024
Actual
Date of last data collection
Anticipated
31/07/2024
Actual
Sample size
Target
30
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
WA

Funding & Sponsors
Funding source category [1] 313829 0
University
Name [1] 313829 0
Murdoch University
Country [1] 313829 0
Australia
Primary sponsor type
University
Name
Murdoch University
Address
90 South Street, Murdoch, 6150, WA
Country
Australia
Secondary sponsor category [1] 315664 0
None
Name [1] 315664 0
Address [1] 315664 0
Country [1] 315664 0

Ethics approval
Ethics application status
Submitted, not yet approved
Ethics committee name [1] 312986 0
Murdoch University Human Research Ethics Committee
Ethics committee address [1] 312986 0
90 South Street, Murdoch, 6150, WA
Ethics committee country [1] 312986 0
Australia
Date submitted for ethics approval [1] 312986 0
30/03/2023
Approval date [1] 312986 0
Ethics approval number [1] 312986 0

Summary
Brief summary
Performing exercise in an environment where the oxygen concentration in the air is lower than that of sea level (i.e. hypoxia) during exercise may mimic the metabolic responses of higher-intensity exercise, whereby a greater reliance on muscle glycogen utilisation occurs. It is therefore likely that the additional stimulus of hypoxia superimposed on a high intensity interval exercise will result in greater metabolic adaptations in the longer-term. That said, exposure to hypoxia may also lower mechanical work sustained during high intensity exercise. Therefore, it is unclear whether the application of hypoxia during exercise will enhance or interfere with the benefits of high intensity interval exercise. Accordingly, the aim of the current research is to determine if high intensity interval exercise in hypoxia (within the context of an exercise program including resistance exercise) enhances insulin sensitivity and glucose tolerance to a greater extent compared to a conventional training in normoxia in individuals who are sedentary and overweight.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 126590 0
A/Prof Timothy J. Fairchild
Address 126590 0
90 South Street, Murdoch, 6150, WA.Murdoch University
Country 126590 0
Australia
Phone 126590 0
+61 8 9360 2959
Fax 126590 0
Email 126590 0
[email protected]
Contact person for public queries
Name 126591 0
Jacky Soo
Address 126591 0
90 South Street, Murdoch, 6150, WA.Murdoch University
Country 126591 0
Australia
Phone 126591 0
+61 421558879
Fax 126591 0
Email 126591 0
[email protected]
Contact person for scientific queries
Name 126592 0
Jacky Soo
Address 126592 0
90 South Street, Murdoch, 6150, WA.Murdoch University
Country 126592 0
Australia
Phone 126592 0
+61 421558879
Fax 126592 0
Email 126592 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

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No documents have been uploaded by study researchers.

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