NCT Number: NCT07326462
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.
Trial opening soon.
Get Notified18 year–40 year
All sexes
Interventional
Not applicable
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.
Healthy volunteers accepted: Yes
Only the study team can determine whether someone qualifies for participation.
Inclusion criteria
Exclusion criteria
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.
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.
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.
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).
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.
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).
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).
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.
Time frame: 3 days
Validated Baecke questionnaire → Physical activity level. Rationale: Captures subjective perception of workload alongside physiological measures.
Time frame: 3 days
Fatigue assessment questionnaires → Subjective fatigue. Rationale: Captures subjective perception of fatigue alongside physiological measures.
Time frame: 3 days
Rating of Perceived Exertion (RPE) → Subjective exercise intensity. Rationale: Captures subjective perception of exertion alongside physiological measures.
Contact information is provided by the study sponsor or research team.
Lithuanian Sports University
Other
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