Healthy ParticipantsNCT07326462
The Effects of Strength Training Volume, Intensity, and Breathing Techniques on Intraocular Pressure and Retinal Blood Vessels
A study testing Normal Breathing and Valsalva maneuver in people with Healthy Participants, run by Lithuanian Sports University.
Trial summary
This study aims to determine the effects of different breathing patterns on ocular vasculature and intraocular pressure (IOP) during isokinetic and isometric strength exercises. It is hypothesized that higher ocular microcirculation changes and IOP values will be observed during the Valsalva maneuver compared to… Read more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Healthy Participants
- What is being tested?
- Normal Breathing and Valsalva maneuver
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- No sites listed yet
- Study dates
- 1 Jan 2026to 1 May 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 18 to 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Subjects 18-40 years old
- Peak IOP <21 mmHg in the modified DTC
- Open angle at gonioscopy
- Optic disc with cup-to-disc ratio <0.6 with no signs of glaucomatous neuropathy
- Not currently taking any medication
- Non-smokers, no physical and mental disabilities
- Blood pressure up 120/80 mmHg and heart rate (HR) 60-90 rpm at rest
- BMI (18.5-34.8) kg/m2
Who cannot join
- Presence of any ocular disease (with the exception of refractive errors)
- Anxiety or depressive disorders
- History of ocular trauma or surgery
- Pregnancy
- Use of any kind of oral/topical steroids
- Any diagnosed chronic health condition such as cardiovascular disease including hypertension and or previous physical injuries that could impact their safe participation
- Evidence of ocular pathology due to narrow anterior chamber angles, elevated IOP greater than or equal to 21mm Hg, optic nerve or retinal pathology, cup: disc ratio of greater than 0.6 or asymmetry of cup: disc ratio of greater than 0. 2.
- Refractive error more than ±4.00 diopters, astigmatism greater than 3.00 diopters.
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
This study aims to determine the effects of different breathing patterns on ocular vasculature and intraocular pressure (IOP) during isokinetic and isometric strength exercises. It is hypothesized that higher ocular microcirculation changes and IOP values will be observed during the Valsalva maneuver compared to normal breathing in both exercise types. Additionally, ocular microcirculation and IOP changes are expected to be more pronounced during isometric exercises than during isokinetic exercises. The results will help establish optimal strength training strategies for both professional athletes and physically active individuals.
Read the detailed description
This study is a randomized controlled trial designed to evaluate the effects of different breathing patterns on ocular vasculature and intraocular pressure (IOP) during isokinetic and isometric strength exercise in healthy young adults.
The study protocol was approved by the Kaunas Regional Biomedical Research Ethics Committee, and all participants provided written informed consent prior to participation, in accordance with the Declaration of Helsinki.
Participants will attend experimental sessions during which ocular and cardiovascular parameters will be assessed before exercise, immediately after exercise, and during the recovery period.
Baseline assessments will include general anthropometric measurements and questionnaires related to physical activity and fatigue, as well as evaluation of ocular surface condition.
Retinal microcirculation will be assessed using non-mydriatic fundus photography, and intraocular pressure will be measured using a portable tonometry method. Blood pressure and oxygen saturation will also be monitored during study sessions.
Each participant will perform a standardized 1-minute strength exercise under two exercise modalities: isokinetic and isometric. A standardized warm-up will precede each exercise session.
Two breathing conditions will be evaluated during exercise: normal breathing and the Valsalva maneuver. The order of exercise modality and breathing condition will be randomized, and experimental sessions will be separated by an adequate washout period.
The planned sample size was determined a priori based on statistical power considerations to ensure adequate power to detect meaningful differences between study conditions.
Data will be analyzed using appropriate statistical methods. Descriptive statistics will be used to summarize study data. Normality of data distribution will be assessed, and non-parametric methods will be applied when appropriate. Repeated-measures and between-condition comparisons will be conducted, with adjustments for multiple comparisons applied as needed. Statistical significance will be set at p < 0.05.
- Conditions
- Healthy Participants
- Being tested
- Normal Breathing, Valsalva maneuver
- Keywords
- intraocular pressure, exercise, Valsalva maneuver, retinal vessels
- Medical subject headings
- Motor Activity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Normal BreathingDiagnostic test
Participants perform the isometric or isokinetic exercise while following a controlled breathing rhythm:
Inhale for 3 seconds
Exhale for 3 seconds
Breathing remains steady and continuous throughout the 1-minute exercise.
Rationale: Represents a natural and safe breathing pattern during physical exertion, serves as the physiological baseline condition.
Valsalva maneuverDiagnostic test
Participants perform the same isometric or isokinetic exercise but finish the trial with a 10-second breath-hold at the end of the 1-minute exercise.
This maneuver increases intrathoracic and intra-abdominal pressures, which are transmitted to ocular and vascular systems.
Rationale: Common in athletic performance, but may cause significant intraocular pressure and retinal vascular fluctuations.
| Study group | Role | What they receive |
|---|---|---|
| Isokinetic exercise arm | Experimental | Protocol: Participants perform a 1-minute maximal voluntary isometric contraction of the knee extensors using a BIODEX dynamometer.
Load setting: The maximum isometric load that each individual can sustain for 1 minute is determined during familiarisation. In the main session, participants work at 80% of their predetermined maximum load to avoid premature muscle failure.
Nature of exercise: Static contraction (muscle generates force without changing length). Receives: Diagnostic Test: Normal Breathing; Diagnostic Test: Valsalva maneuver |
| Isometric exercise arm | Experimental | Protocol: Participants perform 1 minute of repeated isokinetic knee extensions and flexions at a controlled angular velocity on the BIODEX dynamometer.
Velocity settings: Knee extension at 30°/s and knee flexion at 60°/s within the 0°-90° range of motion (0° = full extension).
Nature of exercise: Dynamic contraction (muscle changes length while producing force against constant velocity resistance). Receives: Diagnostic Test: Normal Breathing; Diagnostic Test: Valsalva maneuver |
What is being measured
The primary outcome is the main question the study is designed to answer.
1. Intraocular Pressure (IOP)
Tool: Icare portable tonometer (Icare, Tiolat Oy, Helsinki, Finland).
Description: Measures the pressure inside the eye, caused by the aqueous humor pressing against the eye wall.
Rationale: IOP is a key factor in glaucoma development and progression. Monitoring fluctuations during exercise and different breathing techniques is critical.
Timing: Baseline (before exercise), immediately post-exercise, and at 5, 10, 15 minutes after exercise.
Measured: 3 days
2. Retinal Microcirculation
Tool: Aurora handheld non-mydriatic fundus camera (Optomed, Finland).
Description: Digital fundus photography to measure retinal vessel diameters (arterioles and venules) in the superior and inferior temporal quadrants, near the optic disc margin.
Rationale: Retinal vessel diameter is a biomarker for cardiovascular health and provides insights into ocular blood flow changes during stress.
Timing: Same schedule as IOP (before, immediately after, and 5, 10, 15 minutes post-exercise).
Measured: 3 days
3. Blood pressure (BP)
Tool: Omron BP742N automatic arm blood pressure monitor (Omron Healthcare, Japan).
Description: Monitors systolic and diastolic blood pressure levels.
Rationale: To capture systemic cardiovascular responses during isometric vs. isokinetic exercise and different breathing conditions.
Timing: Baseline, immediately after, 5, 10, and 15 minutes post-exercise.
Measured: 3 days
4. Oxygen Saturation (SpO₂)
Tool: Pulse oximeter (Omron).
Description: Monitors peripheral blood oxygen levels.
Rationale: Evaluates systemic oxygen delivery and breathing effects (especially relevant with Valsalva maneuver).
Timing: During the exercise protocol (exact points not deeply detailed in file but implied to match BP).
Measured: 3 days
5. Eye Dryness
Tool: Schirmer Test (TearFlo strips).
Description: Filter paper strips placed inside the lower eyelid for 5 minutes; length of wetting indicates tear production.
Rationale: Assesses ocular surface health, as exercise and breathing methods may influence tear production and comfort.
Timing: At baseline (before experimental trials).
Measured: 3 days
6. Anthropometric Data
Tools:
Leicester Height Metre for height.
Tanita TBF-300 body composition scale for weight and body fat %.
Derived Measurement: Body Mass Index (BMI = weight/height²).
Rationale: Provides participant characteristics for standardization and analysis.
Measured: 3 days
Questionaire no. 1
Validated Baecke questionnaire → Physical activity level. Rationale: Captures subjective perception of workload alongside physiological measures.
Measured: 3 days
Questionnaire no.2
Fatigue assessment questionnaires → Subjective fatigue. Rationale: Captures subjective perception of fatigue alongside physiological measures.
Measured: 3 days
Questionnaire no. 3
Rating of Perceived Exertion (RPE) → Subjective exercise intensity. Rationale: Captures subjective perception of exertion alongside physiological measures.
Measured: 3 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted8 Jan 2026
- Study start1 Jan 2026 (estimated)
- Primary completion1 Apr 2026 (estimated)
- Study completion1 May 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Healthy ParticipantsStudies 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
- Parallel groups
- Model description
- This is a crossover experimental study with 60 healthy adults, where each participant completes two exercise arms (isometric vs. isokinetic) under two breathing interventions (normal vs. Valsalva), separated by 2-3 days. The design allows controlled comparison of ocular and systemic responses to exercise and breathing techniques within the same individuals.
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Lithuanian Sports University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Vytautas Streckis, phD, Prof., Study director, Lithuanian Sports University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07326462
- Sponsor's protocol ID
- LithuanianSportsU-27
- Status last verified
- Jan 2026
- First submitted
- 17 Dec 2025
- Last updated
- 8 Jan 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 8 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effects of Strength Training Volume, Intensity, and Breathing Techniques on Intraocular Pressure and Retinal Blood Vessels
- ClinicalTrials.gov ID
- NCT07326462
- Acronym / sponsor ID
- LithuanianSportsU-27
- Conditions
- Healthy Participants
- Keywords
- intraocular pressure, exercise, Valsalva maneuver, retinal vessels
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- Lithuanian Sports UniversityUniversity, hospital or other
- Study start
- 1 Jan 2026 (estimated)
- Primary completion
- 1 Apr 2026 (estimated)
- Study completion
- 1 May 2026 (estimated)
- First posted
- 8 Jan 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 study aims to determine the effects of different breathing patterns on ocular vasculature and intraocular pressure (IOP) during isokinetic and isometric strength exercises. It is hypothesized that higher ocular microcirculation changes and IOP values will be observed during the Valsalva maneuver compared to normal breathing in both exercise types. Additionally, ocular microcirculation and IOP changes are expected to be more pronounced during isometric exercises than during isokinetic exercises. The results will help establish optimal strength training strategies for both professional athletes and physically active individuals.
Detailed description
This study is a randomized controlled trial designed to evaluate the effects of different breathing patterns on ocular vasculature and intraocular pressure (IOP) during isokinetic and isometric strength exercise in healthy young adults.
The study protocol was approved by the Kaunas Regional Biomedical Research Ethics Committee, and all participants provided written informed consent prior to participation, in accordance with the Declaration of Helsinki.
Participants will attend experimental sessions during which ocular and cardiovascular parameters will be assessed before exercise, immediately after exercise, and during the recovery period.
Baseline assessments will include general anthropometric measurements and questionnaires related to physical activity and fatigue, as well as evaluation of ocular surface condition.
Retinal microcirculation will be assessed using non-mydriatic fundus photography, and intraocular pressure will be measured using a portable tonometry method. Blood pressure and oxygen saturation will also be monitored during study sessions.
Each participant will perform a standardized 1-minute strength exercise under two exercise modalities: isokinetic and isometric. A standardized warm-up will precede each exercise session.
Two breathing conditions will be evaluated during exercise: normal breathing and the Valsalva maneuver. The order of exercise modality and breathing condition will be randomized, and experimental sessions will be separated by an adequate washout period.
The planned sample size was determined a priori based on statistical power considerations to ensure adequate power to detect meaningful differences between study conditions.
Data will be analyzed using appropriate statistical methods. Descriptive statistics will be used to summarize study data. Normality of data distribution will be assessed, and non-parametric methods will be applied when appropriate. Repeated-measures and between-condition comparisons will be conducted, with adjustments for multiple comparisons applied as needed. Statistical significance will be set at p < 0.05.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- This is a crossover experimental study with 60 healthy adults, where each participant completes two exercise arms (isometric vs. isokinetic) under two breathing interventions (normal vs. Valsalva), separated by 2-3 days. The design allows controlled comparison of ocular and systemic responses to exercise and breathing techniques within the same individuals.
| Arm | Type | Receives |
|---|---|---|
| Isokinetic exercise arm | Experimental | Diagnostic Test: Normal Breathing, Diagnostic Test: Valsalva maneuverProtocol: Participants perform a 1-minute maximal voluntary isometric contraction of the knee extensors using a BIODEX dynamometer. Load setting: The maximum isometric load that each individual can sustain for 1 minute is determined during familiarisation. In the main session, participants work at 80% of their predetermined maximum load to avoid premature muscle failure. Nature of exercise: Static contraction (muscle generates force without changing length). |
| Isometric exercise arm | Experimental | Diagnostic Test: Normal Breathing, Diagnostic Test: Valsalva maneuverProtocol: Participants perform 1 minute of repeated isokinetic knee extensions and flexions at a controlled angular velocity on the BIODEX dynamometer. Velocity settings: Knee extension at 30°/s and knee flexion at 60°/s within the 0°-90° range of motion (0° = full extension). Nature of exercise: Dynamic contraction (muscle changes length while producing force against constant velocity resistance). |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (8 listed)
- Subjects 18-40 years old
- Peak IOP <21 mmHg in the modified DTC
- Open angle at gonioscopy
- Optic disc with cup-to-disc ratio <0.6 with no signs of glaucomatous neuropathy
- Not currently taking any medication
Key exclusion criteria (8 listed)
- Presence of any ocular disease (with the exception of refractive errors)
- Anxiety or depressive disorders
- History of ocular trauma or surgery
- Pregnancy
- Use of any kind of oral/topical 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 |
|---|---|---|
| Normal BreathingParticipants perform the isometric or isokinetic exercise while following a controlled breathing rhythm: Inhale for 3 seconds Exhale for 3 seconds Breathing remains steady and continuous throughout the 1-minute exercise. Rationale: Represents a natural and safe breathing pattern during physical exertion, serves as the physiological baseline condition. | Diagnostic test | Isokinetic exercise arm, Isometric exercise arm |
| Valsalva maneuverParticipants perform the same isometric or isokinetic exercise but finish the trial with a 10-second breath-hold at the end of the 1-minute exercise. This maneuver increases intrathoracic and intra-abdominal pressures, which are transmitted to ocular and vascular systems. Rationale: Common in athletic performance, but may cause significant intraocular pressure and retinal vascular fluctuations. | Diagnostic test | Isokinetic exercise arm, Isometric exercise arm |
Primary outcome
1. Intraocular Pressure (IOP)
Time frame: 3 days
Tool: Icare portable tonometer (Icare, Tiolat Oy, Helsinki, Finland). Description: Measures the pressure inside the eye, caused by the aqueous humor pressing against the eye wall. Rationale: IOP is a key factor in glaucoma development and progression. Monitoring fluctuations during exercise and different breathing techniques is critical. Timing: Baseline (before exercise), immediately post-exercise, and at 5, 10, 15 minutes after exercise.
2. Retinal Microcirculation
Time frame: 3 days
Tool: Aurora handheld non-mydriatic fundus camera (Optomed, Finland). Description: Digital fundus photography to measure retinal vessel diameters (arterioles and venules) in the superior and inferior temporal quadrants, near the optic disc margin. Rationale: Retinal vessel diameter is a biomarker for cardiovascular health and provides insights into ocular blood flow changes during stress. Timing: Same schedule as IOP (before, immediately after, and 5, 10, 15 minutes post-exercise).
3. Blood pressure (BP)
Time frame: 3 days
Tool: Omron BP742N automatic arm blood pressure monitor (Omron Healthcare, Japan). Description: Monitors systolic and diastolic blood pressure levels. Rationale: To capture systemic cardiovascular responses during isometric vs. isokinetic exercise and different breathing conditions. Timing: Baseline, immediately after, 5, 10, and 15 minutes post-exercise.
4. Oxygen Saturation (SpO₂)
Time frame: 3 days
Tool: Pulse oximeter (Omron). Description: Monitors peripheral blood oxygen levels. Rationale: Evaluates systemic oxygen delivery and breathing effects (especially relevant with Valsalva maneuver). Timing: During the exercise protocol (exact points not deeply detailed in file but implied to match BP).
5. Eye Dryness
Time frame: 3 days
Tool: Schirmer Test (TearFlo strips). Description: Filter paper strips placed inside the lower eyelid for 5 minutes; length of wetting indicates tear production. Rationale: Assesses ocular surface health, as exercise and breathing methods may influence tear production and comfort. Timing: At baseline (before experimental trials).
6. Anthropometric Data
Time frame: 3 days
Tools: Leicester Height Metre for height. Tanita TBF-300 body composition scale for weight and body fat %. Derived Measurement: Body Mass Index (BMI = weight/height²). Rationale: Provides participant characteristics for standardization and analysis.
Questionaire no. 1
Time frame: 3 days
Validated Baecke questionnaire → Physical activity level. Rationale: Captures subjective perception of workload alongside physiological measures.
Questionnaire no.2
Time frame: 3 days
Fatigue assessment questionnaires → Subjective fatigue. Rationale: Captures subjective perception of fatigue alongside physiological measures.
Questionnaire no. 3
Time frame: 3 days
Rating of Perceived Exertion (RPE) → Subjective exercise intensity. Rationale: Captures subjective perception of exertion alongside physiological measures.
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 8 Jan 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.
Vytautas Streckis, phD, Prof. study director
Lithuanian Sports University
Questions about this trial
What is this clinical trial studying?
A study testing Normal Breathing and Valsalva maneuver in people with Healthy Participants, run by Lithuanian Sports University.
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 8 inclusion and 8 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: opening soon, as of the sponsor's last update on 8 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
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 Monika Vieversyte-Dvyliene, MD (069031331, monikavieversyte@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
1. Intraocular Pressure (IOP) (time frame: 3 days). The study lists 9 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 8 Jan 2026.