NCT07326462

The Effects of Strength Training Volume, Intensity, and Breathing Techniques on Intraocular Pressure and Retinal Blood Vessels

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 60 (estimated)
• Sponsor: Lithuanian Sports University · Academic / Other
• Sex: All
• Age: 18 Years – 40 Years
• Healthy volunteers: Accepted

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.

Conditions

• Healthy Participants

Interventions

Type	Name	Description
DIAGNOSTIC_TEST	Normal 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_TEST	Valsalva 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.

Timeline

• Start date: 2026-01-01
• Primary completion: 2026-04-01
• Completion: 2026-05-01
• First posted: 2026-01-08
• Last updated: 2026-01-08