Obesity & OverweightHybri-DNCT07300332
Exercise Training and Vitamin D Metabolism
A study testing Exercise training in people with Obesity & Overweight and Vitamin D, run by University of Thessaly at 1 site in Greece.
Trial summary
The prevalence of Vitamin D deficiency is significantly higher in adults with overweight/obesity compared to those with normal body mass index (BMI). The "entrapment" of Vitamin D in adipose tissue due to impaired lipolytic stimulation and/or adipose tissue dysfunction has been proposed as the driving mechanism. Read more about this study
- Who is it for?
- Ages 35 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Obesity & Overweight, Vitamin D
- What is being tested?
- Exercise training
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 30 participants
- Where
- 1 siteGreece
- Study dates
- 10 Nov 2025to 20 Jul 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 35 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- BMI = 25-35 kg/m2
- Absence of musculoskeletal injuries
- Absence of chronic health-related complications
- Non-smokers
Who cannot join
- Consumption of Vitamin D supplements
- Consumption of anti-inflammatory drugs, statins and/or steroids
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Greece1 site, 1 recruiting
- Recruiting
Department of Physical Education and Sport Science, University of Thessaly
Trikala, Karyes, 42100
Athanasios Z Jamurtas, PhD, 2431047054, ajamurt@uth.gr
Ioannis G Fatouros, PhD, 2431047047, ifatouros@uth.gr
About this study
Official title: The Impact of Hybrid-type High-intensity Interval Training on Vitamin D Metabolism in Adults With Overweight/Obesity
The prevalence of Vitamin D deficiency is significantly higher in adults with overweight/obesity compared to those with normal body mass index (BMI). The "entrapment" of Vitamin D in adipose tissue due to impaired lipolytic stimulation and/or adipose tissue dysfunction has been proposed as the driving mechanism. Exercise training has been proposed as a promising strategy to increase mobilization of Vitamin D from adipose tissue, given its well described role in stimulating lipolysis. Indeed, a recent study revealed that participation in moderate-intensity cardiovascular type exercise over winter can mitigate the decline in 25-hydroxyvitamin D [25(OH)D] in adults with overweight/obesity, independent of weight loss. The aim of this study is to investigate the impact of hybrid-type high-intensity interval training over winter on vitamin D metabolism, in adults with overweight/obesity.
Read the detailed description
Thirty adults with overweight/obesity (both males and females) who will meet the inclusion criteria will be randomly assigned to either an Exercise group (n=15) or a Control group (n=15). The Exercise group will participate in three hybrid-type high-intensity interval training sessions per week over a 12-week period, while receiving a balanced diet. The Control group will receive a balanced diet but will not participate in exercise training. Both groups will provide a resting blood sample and undergo assessment of their body composition (via bioelectrical impedance analysis), daily dietary intake (via dietary recalls) and physical activity level (via accelerometry) at baseline (prior to intervention), 6 weeks and 12 weeks.
- Conditions
- Obesity & Overweight, Vitamin D
- Being tested
- Exercise training, Control
- Keywords
- overweight, obesity, vitamin D, 25-hydroxyvitamin D, high-intensity interval training
- Medical subject headings
- Obesity, Overweight
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Exercise trainingOther
Receive a balanced diet and participate in three hybrid-type high-intensity interval training sessions per week over a 12-week period
ControlOther
Receive a balanced diet but abstain from any type of exercise training
| Study group | Role | What they receive |
|---|---|---|
| Exercise group | Experimental | Exercise group will participate in three hybrid-type high-intensity interval training sessions per week over a 12-week period, while receiving a balanced diet Receives: Other: Exercise training |
| Control group | Active comparator | Control group will receive a balanced diet but will not participate in exercise training Receives: Other: Control |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in 25-hydroxyvitamin D concentration
25-OH-VD will be quantitatively determined in serum
Measured: At baseline, 6 weeks and 12 weeks
Change in plasma Vitamin D binding protein concentration
Vitamin D binding protein concentration will be determined in plasma
Measured: At baseline, 6 weeks and 12 weeks
Change in calcium concentration
Calcium concentration will be determined in serum
Measured: At baseline, 6 weeks and 12 weeks
Change in albumin concentration
Albumin concentration will be determined in serum
Measured: At baseline, 6 weeks and 12 weeks
Change in aspartate aminotransferase (SGOT) concentration
SGOT concentration will be determined in serum on a Clinical Chemistry analyzer
Measured: At baseline, 6 weeks and 12 weeks
Change in alanine aminotransferase (SGPT) concentration
SGPT concentration will be determined in serum on a Clinical Chemistry analyzer
Measured: At baseline, 6 weeks and 12 weeks
Change in gamma-glutamyl transferase (γ-GT) concentration
γ-GT concentration will be determined in serum on a Clinical Chemistry analyzer
Measured: At baseline, 6 weeks and 12 weeks
Secondary outcomes (5)
Change in reduced glutathione concentration
Reduced glutathione concentration will be determined in blood erythrocytes
Measured: At baseline, 6 weeks and 12 weeks
Change in oxidized glutathione concentration
Oxidized glutathione concentration will be determined in blood erythrocytes
Measured: At baseline, 6 weeks and 12 weeks
Change in dietary intake
Dietary intake habits will be assessed through dietary recalls
Measured: At baseline, 6 weeks and 12 weeks
Change in physical activity level
Physical activity will be assessed via accelerometry
Measured: At baseline, 6 weeks and 12 weeks
Change in body composition
Body composistion will be assessed via bioelectrical impedance analysis (BIA)
Measured: At baseline, 6 weeks and 12 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Dec 2025
- Study start10 Nov 2025
- Primary completion31 Jan 2026
- Study completion20 Jul 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Obesity & OverweightStudies 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
- Other
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Thessaly
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Dimitrios Draganidis, University of Thessaly
- Investigators
- Dimitrios Draganidis, PhD, Principal investigator, University of Thessaly
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07300332
- Sponsor's protocol ID
- UTH_2612_8.10.2025
- Acronym
- Hybri-D
- Status last verified
- May 2026
- First submitted
- 9 Dec 2025
- Last updated
- 26 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 26 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Impact of Hybrid-type High-intensity Interval Training on Vitamin D Metabolism in Adults With Overweight/Obesity
- ClinicalTrials.gov ID
- NCT07300332
- Acronym / sponsor ID
- Hybri-D / UTH_2612_8.10.2025
- Conditions
- Obesity & Overweight, Vitamin D
- Keywords
- overweight, obesity, vitamin D, 25-hydroxyvitamin D, high-intensity interval training
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- University of ThessalyUniversity, hospital or other
- Study start
- 10 Nov 2025 (actual)
- Primary completion
- 31 Jan 2026 (actual)
- Study completion
- 20 Jul 2026 (estimated)
- First posted
- 23 Dec 2025 (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.
The prevalence of Vitamin D deficiency is significantly higher in adults with overweight/obesity compared to those with normal body mass index (BMI). The "entrapment" of Vitamin D in adipose tissue due to impaired lipolytic stimulation and/or adipose tissue dysfunction has been proposed as the driving mechanism. Exercise training has been proposed as a promising strategy to increase mobilization of Vitamin D from adipose tissue, given its well described role in stimulating lipolysis. Indeed, a recent study revealed that participation in moderate-intensity cardiovascular type exercise over winter can mitigate the decline in 25-hydroxyvitamin D [25(OH)D] in adults with overweight/obesity, independent of weight loss. The aim of this study is to investigate the impact of hybrid-type high-intensity interval training over winter on vitamin D metabolism, in adults with overweight/obesity.
Detailed description
Thirty adults with overweight/obesity (both males and females) who will meet the inclusion criteria will be randomly assigned to either an Exercise group (n=15) or a Control group (n=15). The Exercise group will participate in three hybrid-type high-intensity interval training sessions per week over a 12-week period, while receiving a balanced diet. The Control group will receive a balanced diet but will not participate in exercise training. Both groups will provide a resting blood sample and undergo assessment of their body composition (via bioelectrical impedance analysis), daily dietary intake (via dietary recalls) and physical activity level (via accelerometry) at baseline (prior to intervention), 6 weeks and 12 weeks.
Study design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Exercise group | Experimental | Other: Exercise trainingExercise group will participate in three hybrid-type high-intensity interval training sessions per week over a 12-week period, while receiving a balanced diet |
| Control group | Active comparator | Other: ControlControl group will receive a balanced diet but will not participate in exercise training |
Who may qualify
- Ages
- 35 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- BMI = 25-35 kg/m2
- Absence of musculoskeletal injuries
- Absence of chronic health-related complications
- Non-smokers
Key exclusion criteria (2 listed)
- Consumption of Vitamin D supplements
- Consumption of anti-inflammatory drugs, statins and/or steroids
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 |
|---|---|---|
| Exercise trainingReceive a balanced diet and participate in three hybrid-type high-intensity interval training sessions per week over a 12-week period | Other | Exercise group |
| ControlReceive a balanced diet but abstain from any type of exercise training | Other | Control group |
Primary outcome
Change in 25-hydroxyvitamin D concentration
Time frame: At baseline, 6 weeks and 12 weeks
25-OH-VD will be quantitatively determined in serum
Change in plasma Vitamin D binding protein concentration
Time frame: At baseline, 6 weeks and 12 weeks
Vitamin D binding protein concentration will be determined in plasma
Change in calcium concentration
Time frame: At baseline, 6 weeks and 12 weeks
Calcium concentration will be determined in serum
Change in albumin concentration
Time frame: At baseline, 6 weeks and 12 weeks
Albumin concentration will be determined in serum
Change in aspartate aminotransferase (SGOT) concentration
Time frame: At baseline, 6 weeks and 12 weeks
SGOT concentration will be determined in serum on a Clinical Chemistry analyzer
Change in alanine aminotransferase (SGPT) concentration
Time frame: At baseline, 6 weeks and 12 weeks
SGPT concentration will be determined in serum on a Clinical Chemistry analyzer
Change in gamma-glutamyl transferase (γ-GT) concentration
Time frame: At baseline, 6 weeks and 12 weeks
γ-GT concentration will be determined in serum on a Clinical Chemistry analyzer
5 secondary outcomes
Change in reduced glutathione concentration
Time frame: At baseline, 6 weeks and 12 weeks
Change in oxidized glutathione concentration
Time frame: At baseline, 6 weeks and 12 weeks
Change in dietary intake
Time frame: At baseline, 6 weeks and 12 weeks
Change in physical activity level
Time frame: At baseline, 6 weeks and 12 weeks
Change in body composition
Time frame: At baseline, 6 weeks and 12 weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 26 May 2026.
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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.
Dimitrios Draganidis, PhD principal investigator
University of Thessaly
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Exercise training in people with Obesity & Overweight and Vitamin D, run by University of Thessaly at 1 site in Greece.
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 4 inclusion and 2 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: looking for participants now, as of the sponsor's last update on 26 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 1 site in Greece. 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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Dimitrios Draganidis, PhD (+302431047078, ddraganidis@uth.gr), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in 25-hydroxyvitamin D concentration (time frame: At baseline, 6 weeks and 12 weeks). The study lists 7 primary outcomes in all. 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 26 May 2026.