An interventional study of Exercise training and Control in Obesity & Overweight and Vitamin D, sponsored by University of Thessaly. Recruiting at 1 site in Greece. Open to participants aged 35 Years to 50 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-06.
Sponsored by University of Thessaly · Not applicable, Interventional, and Other
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.
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.
11,522 studies on the registry are indexed under Obesity; 2,033 are open to participants now.
This study's planned enrollment of 30 is below the median of 67 across 9,006 interventional studies indexed under Obesity.
Browse Obesity studies →University of Thessaly is the lead sponsor of 195 studies on the registry; 44 are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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
Other: Exercise training
Control group will receive a balanced diet but will not participate in exercise training
Other: Control
Receive a balanced diet and participate in three hybrid-type high-intensity interval training sessions per week over a 12-week period
Receive a balanced diet but abstain from any type of exercise training
Change in 25-hydroxyvitamin D concentration
25-OH-VD will be quantitatively determined in serum
Time frame: 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
Time frame: At baseline, 6 weeks and 12 weeks
Change in calcium concentration
Calcium concentration will be determined in serum
Time frame: At baseline, 6 weeks and 12 weeks
Change in albumin concentration
Albumin concentration will be determined in serum
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: At baseline, 6 weeks and 12 weeks
Change in reduced glutathione concentration
Reduced glutathione concentration will be determined in blood erythrocytes
Time frame: At baseline, 6 weeks and 12 weeks
Change in oxidized glutathione concentration
Oxidized glutathione concentration will be determined in blood erythrocytes
Time frame: At baseline, 6 weeks and 12 weeks
Change in dietary intake
Dietary intake habits will be assessed through dietary recalls
Time frame: At baseline, 6 weeks and 12 weeks
Change in physical activity level
Physical activity will be assessed via accelerometry
Time frame: At baseline, 6 weeks and 12 weeks
Change in body composition
Body composistion will be assessed via bioelectrical impedance analysis (BIA)
Time frame: At baseline, 6 weeks and 12 weeks
Ran from Nov 2025 to primary completion in Jan 2026, 2 months.
Of 3,680 non-industry interventional studies with no phase under Obesity, half reached primary completion within 23 months of starting (the median), counting those still running; a quarter within 10 and three quarters within 43. This study's 2 months is below that.
Counting every sponsor, half of 3,843 studies reached it within 22 months; a quarter within 10 and three quarters within 42.
Completion moved once since we started tracking on Sep 25, 2026: Jul 2026 → Dec 2026, on Nov 6, 2026.
Earlier changes are on the record history on ClinicalTrials.gov ↗
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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