HealthyNCT06967714
Disentangling the Variability of Exercise-induced Hypoalgesia: the Role of Circulatory Compounds
A study testing Exercise in people with Healthy, run by Université Catholique de Louvain at 1 site in Belgium.
Trial summary
Physical exercise is increasingly recognized as an effective treatment for chronic pain. Studies in humans and animals have shown that a single session of exercise induces a reduction of sensitivity to experimental painful stimuli lasting up to 45 minutes. Read more about this study
- Who is it for?
- Ages 18 to 30 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy
- What is being tested?
- Exercise
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 90 participants
- Where
- 1 siteBelgium
- Study dates
- 14 Apr 2025to 13 Apr 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 30 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Males, or females using hormonal contraception since ≥ 3 months.
- Aged between 18 and 30 years.
- Ability to provide written informed consent.
- Fluency in French or English.
- BMI between 17 and 30 kg/cm2.
Who cannot join
- Regular tobacco use (> 1/month)
- Not willing or able to abstain from alcohol, recreational drugs, coffee, or tea from 24 hours prior to each experimental session.
- Not willing or able to restrain from physical activity > 24h prior to each experimental session, and to be in a fasted state on the day of each experimental session.
- Any evidence for neurological, cardiovascular, respiratory, inflammatory, endocrine, psychiatric, oncological, rheumatological conditions on direct questioning.
- Presence of any medical devices (e.g., cardiac pacemaker) implants or prothesis unless it is beyond discussion that these will not put the subject's safety during the study at risk and will not interfere with the results of the study.
- Any chronic pain condition or recent history thereof (i.e., within the preceding 2 years).
Show all 11Show fewer
- Wounds or skin alteration on testing sites.
- Surgery < 12 months.
- Any drug intake in the past 2 weeks including antibiotics, herbal medicines and other remedies except the following drugs that will be allowed up to 48 hours prior to the experiments: oral paracetamol or ibuprofen for a self-limiting condition (e.g. toothache, bruise). Oral antihistaminics and nasal aerosol and topical treatments for seasonal allergy up to 1 week before the experimental session.
- Any physical activity contraindication.
- Pregnancy.
Trial locations and contacts
1 site in 1 country.
About this study
Physical exercise is increasingly recognized as an effective treatment for chronic pain. Studies in humans and animals have shown that a single session of exercise induces a reduction of sensitivity to experimental painful stimuli lasting up to 45 minutes. In a recent study conducted in our laboratory, we found (1) that this exercise- induced hypoalgesia (EIH) is mainly driven by local changes in muscle nociceptor sensitivity within exercising muscles and (2) that EIH is consistent at a group level but fluctuates across sessions within participants. The first aim of this project is to uncover the mechanism(s) that drive EIH by investigating whether processes that could contribute to an exercise-induced change in muscle nociceptor sensitivity match the fluctuating pattern of EIH. Specifically, we will assess the possible involvement in EIH of the endocannabinoid system (eCB), Kynurenic acid (KynA, a circulating myokine that transiently increases after exercise), and β -endorphins (βE). Using a sample of 90 healthy males and females aged 18 to 30 years, we will measure sensitivity to blunt pressure stimuli before, immediately after, and 45 min after a 25-min cycling exercise to assess muscle nociceptor sensitivity at exercising (rectus femoris muscle) and non-exercising (ventral forearm) muscles. Blood samples will be collected at these time-points to measure plasma levels of eCBs, βE, and KynA. In addition, the effect of sex on EIH is controversial: some studies report no differences between males and females, while others report a greater effect in males or in females. Therefore, a secondary aim of this study is to explore potential sex differences in the manifestation and underlying mechanism(s) of EIH.
- Conditions
- Healthy
- Being tested
- Exercise
- Keywords
- exercise-induced hypoalgesia, mechanisms, pain, exercise
- Medical subject headings
- Pain, Motor Activity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ExerciseBehavioural
25 min cycling exercise at 75% of hear rate reserve. Physical use of one upper-limb will be restricted with a sling.
| Study group | Role | What they receive |
|---|---|---|
| Exercise | Experimental | Participants will complete three experimental sessions. In the first session, they will be asked to complete a set of questionnaires and to do a maximal exercise test. The next two sessions will be identical and will consist in blunt pressure sensitivity assessment-before (T0), immediately after (T1), and 45 min after (T2) a 25 min cycling exercise-at body parts involved (lower limb) and non-involved (upper limb, immobilized) in the exercise. Venous blood samples will be collected concomitantly to the sensory testing procedure. Receives: Behavioral: Exercise |
What is being measured
The primary outcome is the main question the study is designed to answer.
Pressure pain threshold
The investigators will use blunt pressure to preferentially activate the mechano-sensitive deep-tissue nociceptors. The stimuli will be delivered with a manual digital algometer with a contact surface area of 1cm2 (FPIX; Wagner Instruments, Greenwich, USA) connected to a laptop computer through a USB-serial port. A bespoke Matlab (The Mathworks, USA, mathworks.com) script will provide visual feedback of the force application rate to the examinator, while blinding him to the final threshold value. The participants will be asked to report the first onset of pain by pressing on a keyboard key, defining the pressure pain threshold (PPT). The procedure is safe, and there are no side effects to the stimulation
Measured: At each experimental experimental session (2 in total): before (T0), immediately after (T1), and 45 min (T2) after the intervention (cycling exercise).
Secondary outcomes (3)
Plasmatic levels of endocannabinoids
Blood samples will be collected after catheterization of an upper limb vein. The investigators will collect blood samples before, immediately after, and 45 min after exercise (at each session) to investigate potential EIH contributors. Specifically,the plasmatic levels of the endocannabionid (anandamide and 2-Arachidonoylglycerol) will be measured.
Measured: At each experimental experimental session (2 in total): before (T0), immediately after (T1), and 45 min (T2) after the intervention (cycling exercise).
Plasmatic level of Kynurenic acid
Blood samples will be collected after catheterization of an upper limb vein. The investigators will collect blood samples before, immediately after, and 45 min after exercise (at each session) to investigate potential EIH contributors. Specifically, plasmatic levels of kynurenic acid will be measured.
Measured: At each experimental experimental session (2 in total): before (T0), immediately after (T1), and 45 min (T2) after the intervention (cycling exercise).
Plasmatic level of and beta-endorphin
Blood samples will be collected after catheterization of an upper limb vein. The investigators will collect blood samples before, immediately after, and 45 min after exercise (at each session) to investigate potential EIH contributors. Specifically, the plasmatic levels of beta-endorphins will be measured.
Measured: At each experimental experimental session (2 in total): before (T0), immediately after (T1), and 45 min (T2) after the intervention (cycling exercise).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 May 2025
- Study start14 Apr 2025
- Primary completion13 Apr 2026
- Study completion13 Apr 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for HealthyStudies of the same condition, open and under way.
- More trials run by Université Catholique de LouvainThe sponsor's other registered studies.
- 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
- Not applicable
- Intervention model
- Single group
- Model description
- Withi-subject desing. Participants will complete three experimental sessions. In the first session, they will be asked to complete a set of questionnaires and to do a maximal exercise test. The next two sessions will be identical and will consist in blunt pressure sensitivity assessment-before (T0), immediately after (T1), and 45 min after (T2) a 25 min cycling exercise-at body parts involved (lower limb) and non-involved (upper limb, immobilized) in the exercise. Venous blood samples will be collected concomitantly to the sensory testing procedure.
- Masking
- None (open label)
- Enrolment
- 90 participants (actual)
Sponsor and investigators
- Lead sponsor
- Université Catholique de Louvain
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06967714
- Sponsor's protocol ID
- EIH-VAR
- Status last verified
- Jun 2026
- First submitted
- 22 Apr 2025
- Last updated
- 25 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 25 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Disentangling the Variability of Exercise-induced Hypoalgesia: the Role of Circulatory Compounds
- ClinicalTrials.gov ID
- NCT06967714
- Acronym / sponsor ID
- EIH-VAR
- Conditions
- Healthy
- Keywords
- exercise-induced hypoalgesia, mechanisms, pain, exercise
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 90 participants (actual)
- Lead sponsor
- Université Catholique de LouvainUniversity, hospital or other
- Study start
- 14 Apr 2025 (actual)
- Primary completion
- 13 Apr 2026 (actual)
- Study completion
- 13 Apr 2026 (actual)
- First posted
- 13 May 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.
Physical exercise is increasingly recognized as an effective treatment for chronic pain. Studies in humans and animals have shown that a single session of exercise induces a reduction of sensitivity to experimental painful stimuli lasting up to 45 minutes. In a recent study conducted in our laboratory, we found (1) that this exercise- induced hypoalgesia (EIH) is mainly driven by local changes in muscle nociceptor sensitivity within exercising muscles and (2) that EIH is consistent at a group level but fluctuates across sessions within participants. The first aim of this project is to uncover the mechanism(s) that drive EIH by investigating whether processes that could contribute to an exercise-induced change in muscle nociceptor sensitivity match the fluctuating pattern of EIH. Specifically, we will assess the possible involvement in EIH of the endocannabinoid system (eCB), Kynurenic acid (KynA, a circulating myokine that transiently increases after exercise), and β -endorphins (βE). Using a sample of 90 healthy males and females aged 18 to 30 years, we will measure sensitivity to blunt pressure stimuli before, immediately after, and 45 min after a 25-min cycling exercise to assess muscle nociceptor sensitivity at exercising (rectus femoris muscle) and non-exercising (ventral forearm) muscles. Blood samples will be collected at these time-points to measure plasma levels of eCBs, βE, and KynA. In addition, the effect of sex on EIH is controversial: some studies report no differences between males and females, while others report a greater effect in males or in females. Therefore, a secondary aim of this study is to explore potential sex differences in the manifestation and underlying mechanism(s) of EIH.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Withi-subject desing. Participants will complete three experimental sessions. In the first session, they will be asked to complete a set of questionnaires and to do a maximal exercise test. The next two sessions will be identical and will consist in blunt pressure sensitivity assessment-before (T0), immediately after (T1), and 45 min after (T2) a 25 min cycling exercise-at body parts involved (lower limb) and non-involved (upper limb, immobilized) in the exercise. Venous blood samples will be collected concomitantly to the sensory testing procedure.
| Arm | Type | Receives |
|---|---|---|
| Exercise | Experimental | Behavioral: ExerciseParticipants will complete three experimental sessions. In the first session, they will be asked to complete a set of questionnaires and to do a maximal exercise test. The next two sessions will be identical and will consist in blunt pressure sensitivity assessment-before (T0), immediately after (T1), and 45 min after (T2) a 25 min cycling exercise-at body parts involved (lower limb) and non-involved (upper limb, immobilized) in the exercise. Venous blood samples will be collected concomitantly to the sensory testing procedure. |
Who may qualify
- Ages
- 18 to 30 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Males, or females using hormonal contraception since ≥ 3 months.
- Aged between 18 and 30 years.
- Ability to provide written informed consent.
- Fluency in French or English.
- BMI between 17 and 30 kg/cm2.
Key exclusion criteria (11 listed)
- Regular tobacco use (> 1/month)
- Not willing or able to abstain from alcohol, recreational drugs, coffee, or tea from 24 hours prior to each experimental session.
- Not willing or able to restrain from physical activity > 24h prior to each experimental session, and to be in a fasted state on the day of each experimental session.
- Any evidence for neurological, cardiovascular, respiratory, inflammatory, endocrine, psychiatric, oncological, rheumatological conditions on direct questioning.
- Presence of any medical devices (e.g., cardiac pacemaker) implants or prothesis unless it is beyond discussion that these will not put the subject's safety during the study at risk and will not interfere with the results of the study.
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 |
|---|---|---|
| Exercise25 min cycling exercise at 75% of hear rate reserve. Physical use of one upper-limb will be restricted with a sling. | Behavioural | Exercise |
Primary outcome
Pressure pain threshold
Time frame: At each experimental experimental session (2 in total): before (T0), immediately after (T1), and 45 min (T2) after the intervention (cycling exercise).
The investigators will use blunt pressure to preferentially activate the mechano-sensitive deep-tissue nociceptors. The stimuli will be delivered with a manual digital algometer with a contact surface area of 1cm2 (FPIX; Wagner Instruments, Greenwich, USA) connected to a laptop computer through a USB-serial port. A bespoke Matlab (The Mathworks, USA, mathworks.com) script will provide visual feedback of the force application rate to the examinator, while blinding him to the final threshold value. The participants will be asked to report the first onset of pain by pressing on a keyboard key, defining the pressure pain threshold (PPT). The procedure is safe, and there are no side effects to the stimulation
3 secondary outcomes
Plasmatic levels of endocannabinoids
Time frame: At each experimental experimental session (2 in total): before (T0), immediately after (T1), and 45 min (T2) after the intervention (cycling exercise).
Plasmatic level of Kynurenic acid
Time frame: At each experimental experimental session (2 in total): before (T0), immediately after (T1), and 45 min (T2) after the intervention (cycling exercise).
Plasmatic level of and beta-endorphin
Time frame: At each experimental experimental session (2 in total): before (T0), immediately after (T1), and 45 min (T2) after the intervention (cycling exercise).
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 Jun 2026.
- Individual participant dataSharing planned: No
Related trials for Healthy
Recruiting
THE EFFECTS OF GAME-BASED EXERCISE PROGRAMS
Physical Activity, Body Image
Not yet recruitingPhase 1
A Phase I Study of GLR2053 Tablets in Chinese Healthy Adult Participants
Atopic Dermatitis
Recruiting
Colon-delivered Riboflavin and Gut Microbiota Composition
Microbiome Dysbiosis, Gut Health
Not yet recruiting
Neuroergonomic Analysis of a Brain-Computer Interface Device (BCI)
Healthy Volunteers - Male and Female
RecruitingPhase 1
First-in-Human Trial to Assess REGN20423 in Healthy Adult Participants and Adult Participants With Atopic Dermatitis
Healthy Volunteer, Atopic Dermatitis
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.
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 in people with Healthy, run by Université Catholique de Louvain at 1 site in Belgium.
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 5 inclusion and 11 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: finished, as of the sponsor's last update on 25 Jun 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 Belgium. 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?
Pressure pain threshold (time frame: At each experimental experimental session (2 in total): before (T0), immediately after (T1), and 45 min (T2) after the intervention (cycling exercise).). 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 Jun 2026.