Exercise-Induced Circulating Progenitor Cell MobilizationNCT07841561
Exercise Intensity and Circulating CD34+ Progenitor Cell Mobilization in Trained Adults
A study testing Higher-Intensity Work-Matched Cycling Exercise and Lower-Intensity Work-Matched Cycling Exercise in people with Exercise-Induced Circulating Progenitor Cell Mobilization, run by Samarra University at 1 site in Iraq.
Trial summary
This randomized crossover study investigated whether exercise intensity influences the mobilization of circulating CD34+ progenitor cells when total external work is matched. Forty trained male endurance athletes completed two cycling exercise conditions in randomized order: a higher-intensity condition at 70% of peak… Read more about this study
- Who is it for?
- Ages 18 to 35 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Exercise-Induced Circulating Progenitor Cell Mobilization
- What is being tested?
- Higher-Intensity Work-Matched Cycling Exercise and Lower-Intensity Work-Matched Cycling Exercise
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteIraq
- Study dates
- 3 Aug 2026to 9 Sep 2026
- 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 35 years
- Men only
- Healthy volunteers accepted
- Adult
Inclusion Criteria:Eligible participants were healthy adult male endurance-trained athletes engaged in cycling and/or triathlon, within the prespecified age range, with a regular history of endurance training before enrollment. Participants were required to be medically fit to complete maximal exercise testing and both experimental cycling sessions, able to comply with the crossover design and washout requirements, and willing to provide written informed consent before participation.
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Exclusion Criteria:Participants were excluded if they had known cardiovascular, metabolic, hematological, inflammatory, or other medical conditions that could affect exercise responses or participant safety; an acute illness, infection, or musculoskeletal injury at the time of testing; use of medications or substances known to substantially influence cardiovascular, adrenergic, metabolic, or hematological responses; inability to complete the exercise-testing protocol or either experimental session; or failure to comply with the required pre-test or washout procedures.
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Trial locations and contacts
1 site in 1 country.
Iraq1 site
College of Physical Education and Sports Sciences, University of Samarra
Samarra, Muhafazat Salah ad Din, 34010
About this study
Official title: Exercise Intensity Shapes Circulating CD34+ Progenitor-Cell Mobilization Despite Matched External Work: A Randomized Crossover Study
This randomized crossover study investigated whether exercise intensity influences the mobilization of circulating CD34+ progenitor cells when total external work is matched. Forty trained male endurance athletes completed two cycling exercise conditions in randomized order: a higher-intensity condition at 70% of peak work rate (WRpeak) and a lower-intensity condition at 30% WRpeak. Both conditions were performed until 250 kJ of external work had been completed and were separated by a washout period of at least 7 days. Venous blood samples were obtained before exercise, immediately after exercise, and at 15, 30, and 60 minutes of recovery. The primary outcome was the absolute concentration of viable circulating CD34+ cells measured using single-platform flow cytometry. Secondary outcomes included CD34+CD45dim, CD34+CD133+, and CD34+VEGFR2+ cell phenotypes, together with adrenergic, metabolic, chemokine, growth-factor, and cardiovascular responses. The study was designed to determine whether exercise intensity produces distinct progenitor-cell mobilization responses despite identical external work.
Read the detailed description
Acute exercise can transiently alter the number of circulating hematopoietic and vascular-associated progenitor cells. However, exercise intensity and total exercise work are often changed simultaneously, making it difficult to determine whether mobilization is attributable specifically to exercise intensity or simply to a greater amount of external work.
This study used a randomized, counterbalanced, work-matched crossover design to isolate the effect of exercise intensity. Forty trained male endurance athletes completed two cycle-ergometer exercise conditions. In the higher-intensity condition, participants exercised at 70% of their individual peak work rate (WRpeak), whereas in the lower-intensity condition they exercised at 30% WRpeak. Both exercise bouts were terminated when exactly 250 kJ of external mechanical work had been completed. The two experimental sessions were separated by a washout period of at least 7 days.
Participants were assigned to one of two intervention sequences, with either the 70% WRpeak condition or the 30% WRpeak condition performed first. Venous blood samples were collected before exercise (baseline), immediately after exercise, and at 15, 30, and 60 minutes after exercise.
The primary outcome was the absolute concentration of viable circulating CD34+ progenitor cells, quantified by single-platform flow cytometry using counting beads. Additional cellular outcomes included CD34+CD45dim, CD34+CD133+, and CD34+VEGFR2+ phenotypes. Circulating epinephrine, norepinephrine, lactate, glucose, CXCL12/SDF-1, VEGF-A, and other prespecified biochemical markers were assessed alongside heart rate and blood pressure responses.
The principal objective was to compare the temporal pattern and magnitude of circulating CD34+ progenitor-cell mobilization between the two exercise-intensity conditions while holding external work constant. Secondary analyses examined whether differences in progenitor-cell mobilization were associated with exercise-induced adrenergic, metabolic, chemokine, growth-factor, and hemodynamic responses.
- Being tested
- Higher-Intensity Work-Matched Cycling Exercise, Lower-Intensity Work-Matched Cycling Exercise
- Keywords
- Exercise Intensity, CD34+ Progenitor Cells, Circulating Progenitor Cells, Endurance Athletes, Crossover Study, Adrenergic Response, CXCL12
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Higher-Intensity Work-Matched Cycling ExerciseBehavioural
Participants performed cycle-ergometer exercise at 70% of individual peak work rate (WRpeak) until a total external mechanical work of 250 kJ was completed. Venous blood samples were obtained before exercise, immediately after exercise, and at 15, 30, and 60 minutes of recovery.
Lower-Intensity Work-Matched Cycling ExerciseBehavioural
Participants performed cycle-ergometer exercise at 30% of individual peak work rate (WRpeak) until a total external mechanical work of 250 kJ was completed. Venous blood samples were obtained before exercise, immediately after exercise, and at 15, 30, and 60 minutes of recovery.
| Study group | Role | What they receive |
|---|---|---|
| Sequence AB: 70% WRpeak Then 30% WRpeak | Experimental | Participants first completed a cycling exercise bout at 70% of individual peak work rate (WRpeak) until 250 kJ of external work was achieved. After a washout period of at least 7 days, participants completed a second cycling bout at 30% WRpeak, also matched to 250 kJ of external work. Receives: Behavioral: Higher-Intensity Work-Matched Cycling Exercise; Behavioral: Lower-Intensity Work-Matched Cycling Exercise |
| Sequence BA: 30% WRpeak Then 70% WRpeak | Experimental | Participants first completed a cycling exercise bout at 30% of individual peak work rate (WRpeak) until 250 kJ of external work was achieved. After a washout period of at least 7 days, participants completed a second cycling bout at 70% WRpeak, also matched to 250 kJ of external work. Receives: Behavioral: Higher-Intensity Work-Matched Cycling Exercise; Behavioral: Lower-Intensity Work-Matched Cycling Exercise |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change From Baseline in Absolute Circulating Viable CD34+ Progenitor Cell Concentration
Absolute circulating viable CD34+ progenitor cells were quantified in peripheral blood using single-platform flow cytometry with counting beads and expressed as cells/µL. Measurements were obtained before exercise and during recovery after each exercise condition. Change from baseline was calculated for each post-exercise time point and compared between the 70% WRpeak and 30% WRpeak work-matched exercise conditions.
Measured: Baseline, immediately post-exercise, and 15, 30, and 60 minutes post-exercise during each intervention session.
Secondary outcomes (3)
Change From Baseline in Circulating CD34+CD45dim Progenitor Cell Concentration
Circulating CD34+CD45dim progenitor cells were quantified in peripheral blood using flow cytometry and expressed as cells/µL. Measurements were obtained before exercise, immediately after exercise, and at 15, 30, and 60 minutes of recovery during both exercise conditions. Change from baseline was calculated for each post-exercise time point.
Measured: Baseline, immediately post-exercise, and 15, 30, and 60 minutes post-exercise during each intervention session.
Change From Baseline in Circulating CD34+CD133+ Progenitor Cell Concentration
Circulating CD34+CD133+ progenitor cells were quantified in peripheral blood using flow cytometry and expressed as cells/µL. Measurements were obtained before exercise, immediately after exercise, and at 15, 30, and 60 minutes of recovery during both exercise conditions. Change from baseline was calculated for each post-exercise time point.
Measured: Baseline, immediately post-exercise, and 15, 30, and 60 minutes post-exercise during each intervention session.
Change From Baseline in Circulating CD34+VEGFR2+ Progenitor Cell Concentration
Circulating CD34+VEGFR2+ cells, representing a putative angiogenic progenitor-cell phenotype, were quantified in peripheral blood using flow cytometry and expressed as cells/µL. Measurements were obtained before exercise, immediately after exercise, and at 15, 30, and 60 minutes of recovery during both exercise conditions. Change from baseline was calculated for each post-exercise time point.
Measured: Baseline, immediately post-exercise, and 15, 30, and 60 minutes post-exercise during each intervention session.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted25 Sep 2026
- Study start3 Aug 2026
- Primary completion9 Sep 2026
- Study completion9 Sep 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Exercise-Induced Circulating Progenitor Cell MobilizationStudies 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
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Participants completed two work-matched cycling exercise conditions in a randomized, counterbalanced crossover design. Each participant performed exercise at 70% and 30% of individual peak work rate (WRpeak), with both conditions matched for 250 kJ of external work and separated by a washout period of at least 7 days. Participants were assigned to either sequence AB (70% followed by 30% WRpeak) or sequence BA (30% followed by 70% WRpeak).
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 40 participants (actual)
Sponsor and investigators
- Lead sponsor
- Samarra University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Saif Rasheed Ghanim, Samarra University
- Investigators
- SAIF RASHEED GHANIM, PhD, Principal investigator, College of Physical Education and Sports Sciences, University of Samarra
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07841561
- Sponsor's protocol ID
- SRG-CD34-EXINT-2026-01
- Status last verified
- Sep 2026
- First submitted
- 19 Sep 2026
- Last updated
- 25 Sep 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual participant data underlying the results reported in the published article may be shared upon reasonable request.
Study at a glance
From the registry record, last updated by the sponsor on 25 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Exercise Intensity Shapes Circulating CD34+ Progenitor-Cell Mobilization Despite Matched External Work: A Randomized Crossover Study
- ClinicalTrials.gov ID
- NCT07841561
- Acronym / sponsor ID
- SRG-CD34-EXINT-2026-01
- Keywords
- Exercise Intensity, CD34+ Progenitor Cells, Circulating Progenitor Cells, Endurance Athletes, Crossover Study, Adrenergic Response, CXCL12
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 40 participants (actual)
- Lead sponsor
- Samarra UniversityUniversity, hospital or other
- Study start
- 3 Aug 2026 (actual)
- Primary completion
- 9 Sep 2026 (actual)
- Study completion
- 9 Sep 2026 (actual)
- First posted
- 25 Sep 2026 (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.
This randomized crossover study investigated whether exercise intensity influences the mobilization of circulating CD34+ progenitor cells when total external work is matched. Forty trained male endurance athletes completed two cycling exercise conditions in randomized order: a higher-intensity condition at 70% of peak work rate (WRpeak) and a lower-intensity condition at 30% WRpeak. Both conditions were performed until 250 kJ of external work had been completed and were separated by a washout period of at least 7 days. Venous blood samples were obtained before exercise, immediately after exercise, and at 15, 30, and 60 minutes of recovery. The primary outcome was the absolute concentration of viable circulating CD34+ cells measured using single-platform flow cytometry. Secondary outcomes included CD34+CD45dim, CD34+CD133+, and CD34+VEGFR2+ cell phenotypes, together with adrenergic, metabolic, chemokine, growth-factor, and cardiovascular responses. The study was designed to determine whether exercise intensity produces distinct progenitor-cell mobilization responses despite identical external work.
Detailed description
Acute exercise can transiently alter the number of circulating hematopoietic and vascular-associated progenitor cells. However, exercise intensity and total exercise work are often changed simultaneously, making it difficult to determine whether mobilization is attributable specifically to exercise intensity or simply to a greater amount of external work.
This study used a randomized, counterbalanced, work-matched crossover design to isolate the effect of exercise intensity. Forty trained male endurance athletes completed two cycle-ergometer exercise conditions. In the higher-intensity condition, participants exercised at 70% of their individual peak work rate (WRpeak), whereas in the lower-intensity condition they exercised at 30% WRpeak. Both exercise bouts were terminated when exactly 250 kJ of external mechanical work had been completed. The two experimental sessions were separated by a washout period of at least 7 days.
Participants were assigned to one of two intervention sequences, with either the 70% WRpeak condition or the 30% WRpeak condition performed first. Venous blood samples were collected before exercise (baseline), immediately after exercise, and at 15, 30, and 60 minutes after exercise.
The primary outcome was the absolute concentration of viable circulating CD34+ progenitor cells, quantified by single-platform flow cytometry using counting beads. Additional cellular outcomes included CD34+CD45dim, CD34+CD133+, and CD34+VEGFR2+ phenotypes. Circulating epinephrine, norepinephrine, lactate, glucose, CXCL12/SDF-1, VEGF-A, and other prespecified biochemical markers were assessed alongside heart rate and blood pressure responses.
The principal objective was to compare the temporal pattern and magnitude of circulating CD34+ progenitor-cell mobilization between the two exercise-intensity conditions while holding external work constant. Secondary analyses examined whether differences in progenitor-cell mobilization were associated with exercise-induced adrenergic, metabolic, chemokine, growth-factor, and hemodynamic responses.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
- Model description
- Participants completed two work-matched cycling exercise conditions in a randomized, counterbalanced crossover design. Each participant performed exercise at 70% and 30% of individual peak work rate (WRpeak), with both conditions matched for 250 kJ of external work and separated by a washout period of at least 7 days. Participants were assigned to either sequence AB (70% followed by 30% WRpeak) or sequence BA (30% followed by 70% WRpeak).
| Arm | Type | Receives |
|---|---|---|
| Sequence AB: 70% WRpeak Then 30% WRpeak | Experimental | Behavioral: Higher-Intensity Work-Matched Cycling Exercise, Behavioral: Lower-Intensity Work-Matched Cycling ExerciseParticipants first completed a cycling exercise bout at 70% of individual peak work rate (WRpeak) until 250 kJ of external work was achieved. After a washout period of at least 7 days, participants completed a second cycling bout at 30% WRpeak, also matched to 250 kJ of external work. |
| Sequence BA: 30% WRpeak Then 70% WRpeak | Experimental | Behavioral: Higher-Intensity Work-Matched Cycling Exercise, Behavioral: Lower-Intensity Work-Matched Cycling ExerciseParticipants first completed a cycling exercise bout at 30% of individual peak work rate (WRpeak) until 250 kJ of external work was achieved. After a washout period of at least 7 days, participants completed a second cycling bout at 70% WRpeak, also matched to 250 kJ of external work. |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
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 |
|---|---|---|
| Higher-Intensity Work-Matched Cycling ExerciseParticipants performed cycle-ergometer exercise at 70% of individual peak work rate (WRpeak) until a total external mechanical work of 250 kJ was completed. Venous blood samples were obtained before exercise, immediately after exercise, and at 15, 30, and 60 minutes of recovery. | Behavioural | Sequence AB: 70% WRpeak Then 30% WRpeak, Sequence BA: 30% WRpeak Then 70% WRpeak |
| Lower-Intensity Work-Matched Cycling ExerciseParticipants performed cycle-ergometer exercise at 30% of individual peak work rate (WRpeak) until a total external mechanical work of 250 kJ was completed. Venous blood samples were obtained before exercise, immediately after exercise, and at 15, 30, and 60 minutes of recovery. | Behavioural | Sequence AB: 70% WRpeak Then 30% WRpeak, Sequence BA: 30% WRpeak Then 70% WRpeak |
Primary outcome
Change From Baseline in Absolute Circulating Viable CD34+ Progenitor Cell Concentration
Time frame: Baseline, immediately post-exercise, and 15, 30, and 60 minutes post-exercise during each intervention session.
Absolute circulating viable CD34+ progenitor cells were quantified in peripheral blood using single-platform flow cytometry with counting beads and expressed as cells/µL. Measurements were obtained before exercise and during recovery after each exercise condition. Change from baseline was calculated for each post-exercise time point and compared between the 70% WRpeak and 30% WRpeak work-matched exercise conditions.
3 secondary outcomes
Change From Baseline in Circulating CD34+CD45dim Progenitor Cell Concentration
Time frame: Baseline, immediately post-exercise, and 15, 30, and 60 minutes post-exercise during each intervention session.
Change From Baseline in Circulating CD34+CD133+ Progenitor Cell Concentration
Time frame: Baseline, immediately post-exercise, and 15, 30, and 60 minutes post-exercise during each intervention session.
Change From Baseline in Circulating CD34+VEGFR2+ Progenitor Cell Concentration
Time frame: Baseline, immediately post-exercise, and 15, 30, and 60 minutes post-exercise during each intervention session.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 25 Sep 2026.
- Individual participant dataSharing planned: Yes. De-identified individual participant data underlying the results reported in the published article may be shared upon reasonable request.
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.
SAIF RASHEED GHANIM, PhD principal investigator
College of Physical Education and Sports Sciences, University of Samarra
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Higher-Intensity Work-Matched Cycling Exercise and Lower-Intensity Work-Matched Cycling Exercise in people with Exercise-Induced Circulating Progenitor Cell Mobilization, run by Samarra University at 1 site in Iraq.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
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: finished, as of the sponsor's last update on 25 Sep 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 Iraq. 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 is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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 From Baseline in Absolute Circulating Viable CD34+ Progenitor Cell Concentration (time frame: Baseline, immediately post-exercise, and 15, 30, and 60 minutes post-exercise during each intervention session.). 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 25 Sep 2026.