Healthy Participants
Conditions
Keywords
intraocular pressure, exercise, Valsalva maneuver, retinal vessels
Brief 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 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.
Interventions
DIAGNOSTIC_TESTNormal Breathing
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.
DIAGNOSTIC_TESTValsalva maneuver
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.
Sponsors
Lithuanian Sports University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Masking description
Triple (Participant, Investigator, Outcomes Assessor)
Intervention 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.
Eligibility
Sex/Gender
ALL
Age
18 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
1. Subjects 18-40 years old 2. Peak IOP \<21 mmHg in the modified DTC 3. Open angle at gonioscopy 4. Optic disc with cup-to-disc ratio \<0.6 with no signs of glaucomatous neuropathy 5. Not currently taking any medication 6. Non-smokers, no physical and mental disabilities 7. Blood pressure up 120/80 mmHg and heart rate (HR) 60-90 rpm at rest 8. BMI (18.5-34.8) kg/m2
Exclusion criteria
1. Presence of any ocular disease (with the exception of refractive errors) 2. Anxiety or depressive disorders 3. History of ocular trauma or surgery 4. Pregnancy 5. Use of any kind of oral/topical steroids 6. Any diagnosed chronic health condition such as cardiovascular disease including hypertension and or previous physical injuries that could impact their safe participation 7. 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. 8. Refractive error more than ±4.00 diopters, astigmatism greater than 3.00 diopters.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 1. Intraocular Pressure (IOP) | 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 | 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) | 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) | 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 | 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 | 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 | 3 days | Validated Baecke questionnaire → Physical activity level. Rationale: Captures subjective perception of workload alongside physiological measures. |
| Questionnaire no.2 | 3 days | Fatigue assessment questionnaires → Subjective fatigue. Rationale: Captures subjective perception of fatigue alongside physiological measures. |
| Questionnaire no. 3 | 3 days | Rating of Perceived Exertion (RPE) → Subjective exercise intensity. Rationale: Captures subjective perception of exertion alongside physiological measures. |
Contacts
Primary ContactMonika Vieversyte-Dvyliene, MD
Outcome results
None listed