General HealthNCT05249205
The Effect of Training Frequency on Improvements in VO2max With REHIT
A study testing REHIT1 and REHIT2 in people with General Health, run by University of Stirling at 3 sites in United Kingdom.
Trial summary
Many people do not manage to do the recommended amount of physical activity for improving general health and wellbeing, and a common reason for this is lack of time. Sprint interval training (SIT) has been suggested to be a time-efficient alternative to current exercise recommendations, but most SIT protocols are not… Read more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- General Health
- What is being tested?
- REHIT1 and REHIT2
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 15 participants
- Where
- 3 sitesUnited Kingdom
- Study dates
- 21 Feb 2022to 30 Aug 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Apparently healthy
- Sedentary or recreationally active
Who cannot join
- Classified as highly physically active on the International Physical Activity Questionnaire (IPAQ)
- Answering 'Yes' to any of the questions of a standard Physical Activity Readiness Questionnaire (PAR-Q)
- Resting heart rate >100 bpm
- Resting blood pressure > 140/90 mm Hg
- BMI > 35 kg/m2
- Testing positive for Covid-19
- Pregnant women
Trial locations and contacts
3 sites in 1 country.
United Kingdom3 sites
University of Stirling
Stirling, Stirlingshire, FK9 4LA
Swansea University
Swansea, SA1 8EN
University of Worcester
Worcester, Worcestershire
About this study
Official title: The Effect of Training Frequency on Improvements in Maximal Aerobic Capacity With Reduced-exertion High-intensity Interval Training (REHIT)
Many people do not manage to do the recommended amount of physical activity for improving general health and wellbeing, and a common reason for this is lack of time. Sprint interval training (SIT) has been suggested to be a time-efficient alternative to current exercise recommendations, but most SIT protocols are not actually as time-efficient as claimed. However, it has previously been shown that the training time commitment of common SIT protocols can be substantially reduced while remaining effective at improving key health markers such as aerobic fitness, insulin function and blood pressure. For example, the reduced-exertion high-intensity interval training (REHIT) protocol consists of two 20-second 'all-out' cycle sprints within a 10-minute low-intensity exercise session. There is some evidence that REHIT is just as effective at improving aerobic fitness with 2 exercise sessions per week compared to 3 or 4 sessions. However, it remains unknown if improvements in aerobic fitness are reduced if just a single REHIT session is performed each week. Therefore, the aim of the present study is to compare improvements in aerobic fitness levels between a control group (no training intervention), a group performing a single REHIT session per week, and a group performing 2 REHIT sessions per week.
Read the detailed description
Up to 45 apparently healthy participants will be recruited at multiple sites. Eligible participants will complete a fitness test to measure pre-training maximal aerobic capacity (V̇O2max). Participants will start cycling on a stationary bike at a low intensity (30 W). The intensity will increase by 1 W every 3 seconds until volitional exhaustion or an inability to maintain a pedalling frequency of >60 rpm. Expired O2 and CO2 will be continuously measured breath-by-breath using an online gas analyser. V̇O2max will be determined as the highest value for a 15-breath rolling average of V̇O2. V̇O2max will be accepted if at least 2 of the following criteria are met: volitional exhaustion / inability to maintain a pedal frequency of 60 rpm, RER>1.10, a plateau in V̇O2, and/or heart rate within 10 bpm of the age predicted maximum (220-age).
Participants will then be randomised into one of 3 groups, performing either 1 or 2 REHIT training sessions per week, or no training intervention (control group). Randomisation will be performed using the sealed envelope method. Participants in the control group will be asked to maintain their regular lifestyle for 6 weeks. Participants in the training groups will perform 6 weeks of REHIT. Each REHIT session involves 10 min of unloaded pedalling interspersed with 2 all-out cycle sprints against a resistance equivalent to 7.5% of the participant's body weight. Sprint duration will be 10 s in week 1, 15 s in week 2, and 20 s in the remaining 4 weeks. The first sprint will finish at 2 min and the second sprint will finish at 6 min. Participants will be instructed to start pedalling as fast as they can ~2-3 s before applying the sprint resistance, and to keep pedalling as fast as they can during the sprint. Verbal encouragement will be provided. Heart rate and power output will be measured throughout each 10-minute exercise session. The post-training V̇O2max test will be scheduled 3 days following the last training session.
- Conditions
- General Health
- Being tested
- REHIT1, REHIT2
- Keywords
- Reduced-exertion high-intensity interval training, REHIT, Training frequency, Fitness
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
REHIT1Behavioural
Also called Reduced-exertion high-intensity interval training / single session per week
This intervention involves a single REHIT exercise session per week. REHIT involves 10 minutes of unloaded cycling on a stationary bike interspersed with two 20-second 'all-out' cycle sprints against a resistance equivalent to 7.5% of body mass.
REHIT2Behavioural
Also called Reduced-exertion high-intensity interval training / 2 sessions per week
This intervention is the same as that for the REHIT1 intervention, but with 2 sessions per week instead of 1.
| Study group | Role | What they receive |
|---|---|---|
| Control | No intervention | Participants in the control group will be asked to maintain their regular lifestyle for the duration of the study. They will not receive an intervention. |
| REHIT1 | Experimental | Participants in the REHIT1 group will perform a single REHIT session per week for 6 weeks. Receives: Behavioral: REHIT1 |
| REHIT2 | Experimental | Participants in the REHIT2 group will perform 2 REHIT sessions per week for 6 weeks. Receives: Behavioral: REHIT2 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in maximal aerobic capacity (VO2max)
VO2max is the greatest volume of oxygen an individual can consume per minute. It is a key health marker.
Measured: Pre-intervention and 3 days following completion of the intervention.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Feb 2022
- Study start21 Feb 2022
- Primary completion30 May 2025
- Study completion30 Aug 2025
Why it stopped: Insufficient recruitment
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for General HealthStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Randomised controlled trial
- Masking
- None (open label)
- Enrolment
- 15 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Stirling
- Sponsor type
- University, hospital or other
- Collaborators
- Swansea University, University of Worcester
- Responsible party
- Principal investigator, Niels Vollaard, University of Stirling
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05249205
- Sponsor's protocol ID
- NICR4056
- Status last verified
- Apr 2026
- First submitted
- 8 Feb 2022
- Last updated
- 5 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Anonymised IPD can be provided to other researchers on request, if the data are of use to answer a valid research question.
Study at a glance
From the registry record, last updated by the sponsor on 5 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Training Frequency on Improvements in Maximal Aerobic Capacity With Reduced-exertion High-intensity Interval Training (REHIT)
- ClinicalTrials.gov ID
- NCT05249205
- Acronym / sponsor ID
- NICR4056
- Conditions
- General Health
- Keywords
- Reduced-exertion high-intensity interval training, REHIT, Training frequency, Fitness
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Insufficient recruitment
- Enrolment
- 15 participants (actual)
- Lead sponsor
- University of StirlingUniversity, hospital or other
- Collaborators
- Swansea University, University of Worcester
- Study start
- 21 Feb 2022 (actual)
- Primary completion
- 30 May 2025 (actual)
- Study completion
- 30 Aug 2025 (actual)
- First posted
- 21 Feb 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Many people do not manage to do the recommended amount of physical activity for improving general health and wellbeing, and a common reason for this is lack of time. Sprint interval training (SIT) has been suggested to be a time-efficient alternative to current exercise recommendations, but most SIT protocols are not actually as time-efficient as claimed. However, it has previously been shown that the training time commitment of common SIT protocols can be substantially reduced while remaining effective at improving key health markers such as aerobic fitness, insulin function and blood pressure. For example, the reduced-exertion high-intensity interval training (REHIT) protocol consists of two 20-second 'all-out' cycle sprints within a 10-minute low-intensity exercise session. There is some evidence that REHIT is just as effective at improving aerobic fitness with 2 exercise sessions per week compared to 3 or 4 sessions. However, it remains unknown if improvements in aerobic fitness are reduced if just a single REHIT session is performed each week. Therefore, the aim of the present study is to compare improvements in aerobic fitness levels between a control group (no training intervention), a group performing a single REHIT session per week, and a group performing 2 REHIT sessions per week.
Detailed description
Up to 45 apparently healthy participants will be recruited at multiple sites. Eligible participants will complete a fitness test to measure pre-training maximal aerobic capacity (V̇O2max). Participants will start cycling on a stationary bike at a low intensity (30 W). The intensity will increase by 1 W every 3 seconds until volitional exhaustion or an inability to maintain a pedalling frequency of >60 rpm. Expired O2 and CO2 will be continuously measured breath-by-breath using an online gas analyser. V̇O2max will be determined as the highest value for a 15-breath rolling average of V̇O2. V̇O2max will be accepted if at least 2 of the following criteria are met: volitional exhaustion / inability to maintain a pedal frequency of 60 rpm, RER>1.10, a plateau in V̇O2, and/or heart rate within 10 bpm of the age predicted maximum (220-age).
Participants will then be randomised into one of 3 groups, performing either 1 or 2 REHIT training sessions per week, or no training intervention (control group). Randomisation will be performed using the sealed envelope method. Participants in the control group will be asked to maintain their regular lifestyle for 6 weeks. Participants in the training groups will perform 6 weeks of REHIT. Each REHIT session involves 10 min of unloaded pedalling interspersed with 2 all-out cycle sprints against a resistance equivalent to 7.5% of the participant's body weight. Sprint duration will be 10 s in week 1, 15 s in week 2, and 20 s in the remaining 4 weeks. The first sprint will finish at 2 min and the second sprint will finish at 6 min. Participants will be instructed to start pedalling as fast as they can ~2-3 s before applying the sprint resistance, and to keep pedalling as fast as they can during the sprint. Verbal encouragement will be provided. Heart rate and power output will be measured throughout each 10-minute exercise session. The post-training V̇O2max test will be scheduled 3 days following the last training session.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
- Model description
- Randomised controlled trial
| Arm | Type | Receives |
|---|---|---|
| Control | No intervention | –Participants in the control group will be asked to maintain their regular lifestyle for the duration of the study. They will not receive an intervention. |
| REHIT1 | Experimental | Behavioral: REHIT1Participants in the REHIT1 group will perform a single REHIT session per week for 6 weeks. |
| REHIT2 | Experimental | Behavioral: REHIT2Participants in the REHIT2 group will perform 2 REHIT sessions per week for 6 weeks. |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (2 listed)
- Apparently healthy
- Sedentary or recreationally active
Key exclusion criteria (7 listed)
- Classified as highly physically active on the International Physical Activity Questionnaire (IPAQ)
- Answering 'Yes' to any of the questions of a standard Physical Activity Readiness Questionnaire (PAR-Q)
- Resting heart rate >100 bpm
- Resting blood pressure > 140/90 mm Hg
- BMI > 35 kg/m2
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| REHIT1Also: Reduced-exertion high-intensity interval training / single session per weekThis intervention involves a single REHIT exercise session per week. REHIT involves 10 minutes of unloaded cycling on a stationary bike interspersed with two 20-second 'all-out' cycle sprints against a resistance equivalent to 7.5% of body mass. | Behavioural | REHIT1 |
| REHIT2Also: Reduced-exertion high-intensity interval training / 2 sessions per weekThis intervention is the same as that for the REHIT1 intervention, but with 2 sessions per week instead of 1. | Behavioural | REHIT2 |
Primary outcome
Change in maximal aerobic capacity (VO2max)
Time frame: Pre-intervention and 3 days following completion of the intervention.
VO2max is the greatest volume of oxygen an individual can consume per minute. It is a key health marker.
Results and safety
The study was stopped early (reason given: Insufficient recruitment). Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 May 2026.
- Individual participant dataSharing planned: Yes. Anonymised IPD can be provided to other researchers on request, if the data are of use to answer a valid research question.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing REHIT1 and REHIT2 in people with General Health, run by University of Stirling at 3 sites in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 5 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study was stopped early (reason given: Insufficient recruitment). Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in maximal aerobic capacity (VO2max) (time frame: Pre-intervention and 3 days following completion of the intervention.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 5 May 2026.