An interventional study of Eye Dominance-Based Visual Training and Standard Volleyball Warm-up in Eye Dominance-based Visual Training and Volleyball Players, sponsored by Istinye University. Not yet recruiting. Open to participants aged 18 Years to 30 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-28.
Sponsored by Istinye University · Not applicable, Interventional, and Treatment
Eye dominance refers to the preference for one eye when processing visual information and may influence visual-motor integration and motor coordination. In volleyball, where rapid decision-making, accurate target tracking, and precise hand-eye coordination are essential, visual processing plays a critical role in upper extremity performance. Although previous studies have investigated eye dominance and visual training in relation to motor control and athletic performance, evidence regarding their acute effects in volleyball players remains limited. This study aims to investigate the acute effects of eye dominance-based visual training on upper extremity motor performance in volleyball players. By evaluating a single-session, low-cost, and equipment-minimal visual training protocol, the study seeks to determine whether targeted visual exercises can produce measurable improvements in motor performance. The findings may contribute to the development of individualized visual-motor training strategies to support athletic performance and inform future research in sports science, physiotherapy, and motor control.
Eye dominance refers to the tendency of the brain to rely more heavily on visual information from one eye than the other. Similar to hand dominance, eye dominance may influence visual processing, spatial awareness, and visual-motor coordination. However, dominant eye and dominant hand do not always occur on the same side, a condition known as cross-dominance. Previous research has suggested that the relationship between eye and hand dominance may be relevant to motor coordination and performance, highlighting the importance of individualized approaches to assessing visual-motor function in sports.
Stereoscopic vision, which enables depth perception through the integration of visual information from both eyes, is essential for accurately estimating distances, tracking moving objects, and responding to dynamic environments. These abilities are particularly important in volleyball, a sport characterized by rapid ball movement, frequent changes in player positioning, and the need for precise timing and quick decision-making. Technical skills such as serving, passing, blocking, and spiking require effective visual tracking, rapid reactions, and accurate upper extremity movements. Therefore, visual processing and visual-motor integration may contribute to upper extremity motor performance in volleyball players.
Previous studies in optometry, neuroscience, and sports science have examined eye dominance, binocular vision, visual processing, and their potential relationships with motor control and athletic performance. Research on visual training has also suggested that targeted exercises may improve selected visual performance parameters, including dynamic visual acuity, balance, reaction time, and visual-motor coordination. Furthermore, the integration of visual information with proprioceptive input is important for the precise control of upper extremity movements. These factors may be particularly relevant to volleyball players, who repeatedly perform high-velocity overhead movements and are susceptible to shoulder and other upper extremity overuse injuries. However, evidence regarding the immediate effects of eye dominance-based visual training on upper extremity motor performance in volleyball players remains limited.
The aim of this study is to investigate the acute effects of eye dominance-based visual training on upper extremity motor performance in volleyball players. The study will focus on whether a single session of targeted visual exercises can produce measurable changes in motor performance. Unlike training programs that require repeated sessions over several weeks, the proposed protocol is designed to be brief, practical, low-cost, and feasible to implement in sports settings with minimal equipment. By examining the immediate responses to visual training, this study seeks to contribute to the understanding of the potential relationship between eye dominance, visual-motor integration, and upper extremity motor performance.
The findings may provide preliminary evidence regarding the potential value of incorporating individualized visual exercises into volleyball training and physiotherapy practice. In addition, the study may help inform the development of personalized visual-motor training strategies tailored to athletes' visual dominance characteristics and performance needs. Further research may build on these findings to investigate the effects of repeated training sessions, the long-term retention of potential improvements, and the transfer of changes in motor performance to sport-specific skills.
Istinye University is the lead sponsor of 221 studies on the registry; 94 are open to participants now.
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You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants complete the standard volleyball warm-up plus a single session of eye dominance-based visual training. The total session duration is matched to the control group.
Behavioral: Eye Dominance-Based Visual Training
Participants complete only the standard volleyball warm-up, with a total duration equal to that of the experimental group.
Behavioral: Standard Volleyball Warm-up
Behavioral: Eye Dominance-Based Visual Training A single-session visual training protocol performed after the dominant eye is identified with the Miles test. It has five stations: (1) eye massage and palming for 30-60 seconds; (2) a letter saccade station, with fast shifts between letter charts, reading aloud and directional responses; (3) an anti-saccade station, with a response opposite to a colored cue, followed by receiving or passing a volleyball; (4) a Brock string station, with focusing on colored beads, followed by ball control or passing; (5) dynamic gaze stabilization, with fixation on colored targets while the eyes and the head/arm move in opposite directions. Each station is done for 3 sets of 10-15 repetitions, separately for the dominant and non-dominant eye. Arm: Eye Dominance Training Group
The standard volleyball warm-up routine that is normally done before training. Arms: Eye Dominance Training Group, Control Group
Seated Medicine Ball Throw Distance
Upper body explosive power is assessed with the seated overhead medicine ball throw test. The participant sits with the back against a wall and the legs extended, then throws a 2-kg medicine ball. The distance from the wall to the landing point is measured in centimeters. The test is done three times and the best throw is recorded.
Time frame: Baseline (pre-intervention) and immediately after the single intervention session
Nelson Hand Reaction Time
Visual-motor reaction time is assessed with the Nelson Hand Reaction Test. The participant sits with the dominant elbow resting on a table and catches a vertically dropped ruler released without warning. The catch distance (cm) is recorded over five trials. The highest and lowest values are discarded and the remaining three are averaged. Reaction time is calculated as t = √(2d/g).
Time frame: Baseline (pre-intervention) and immediately after the single intervention session
Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST) Score
Upper extremity stability and shoulder girdle neuromuscular control are assessed with the Closed Kinetic Chain Upper Extremity Stability Test. In a push-up position (modified for females) with the hands 90 cm apart, the participant alternately touches the opposite hand for 15 seconds. The test is done three times with 45-second rest intervals, and the mean number of touches is recorded.
Time frame: Baseline (pre-intervention) and immediately after the single intervention session
Scapular Muscle Endurance Test (SMET) Holding Time
The endurance of the middle and lower trapezius and rhomboid muscles is assessed with the Scapular Muscle Endurance Test. Facing a wall, with the elbows flexed to 90° and a bar placed between the elbows, the participant applies 1 kg of external rotation force to a dynamometer and holds the position as long as possible. The test ends if the bar falls, 90° elbow flexion is lost, or discomfort occurs. The best holding time (seconds) from two trials is recorded.
Time frame: Baseline (pre-intervention) and immediately after the single intervention session
Eye Dominance Determined by the Miles Test
Eye dominance is determined with the Miles test. With arms extended, the participant forms a triangle with the thumbs and index fingers and, with both eyes open, focuses on a target about 3 meters away. The eyes are then closed one at a time; the eye that keeps the target aligned within the triangle is recorded as dominant (right/left). The test is done under controlled indoor lighting.
Time frame: Baseline (before the intervention)
No study locations are listed for this record.
Plan to share: Undecided
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