Eye-Hand Cross-Dominance and Upper Extremity Performance in Volleyball Players

Comparison of Upper Extremity Muscle Strength and Motor Performance Between Volleyball Players With and Without Crossed Eye-Hand Dominance

Eye and hand dominance may influence visuomotor coordination, motor control, and upper extremity performance in athletes. Crossed eye-hand dominance occurs when the dominant eye and dominant hand are located on opposite sides of the body. However, evidence regarding the relationship between crossed eye-hand dominance and upper extremity performance in volleyball players remains limited.

This observational cross-sectional study aims to compare upper extremity muscle strength and motor performance between volleyball players with and without crossed eye-hand dominance. Participants' eye and hand dominance will be determined using standardized assessments. Upper extremity muscle strength and motor performance outcomes will then be measured and compared between the two groups.

Study Overview

• Status: Recruiting
• Conditions: Volleyball Player
• Intervention / Treatment: Other: Volleyball Players With Crossed Eye-Hand Dominance; Other: Volleyball Players Without Crossed Eye-Hand Dominance

• Study Type: Observational
• Enrollment (Estimated): 30

Contacts and Locations

• Study Contact: Name: Kubra Kardes, Asst. Prof.; Phone Number: 05387115631; Email: kubrakoce@gmail.com

Study Locations

• Turkey (Türkiye)
  • Istanbul, Turkey (Türkiye), 34010
    • Recruiting
    • Istinye University
    • Contact: Kubra Kardes, Asst.Prof; Phone Number: 05387115631; Email: kubrakoce@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Probability Sample

Study Population

Male and female volleyball players aged 18 to 30 years who have regularly participated in volleyball for at least three years and currently train at least three days per week will be recruited.

Description

Inclusion Criteria:

• Aged between 18 and 30 years.
• Male or female volleyball player.
• At least three years of active volleyball participation.
• Currently training at least three days per week.
• No upper extremity injury within the previous six months.
• Normal or corrected-to-normal visual acuity with eyeglasses or contact lenses.
• Willing to participate and able to provide written informed consent.

Exclusion Criteria:

• History or presence of an acute or chronic musculoskeletal disorder that may affect study assessments.
• Presence of a neurological or vestibular system disorder.
• Presence of visual field loss, strabismus, or a severe refractive error that cannot be adequately corrected.
• History of shoulder, elbow, or hand surgery within the previous six months.
• Not currently participating regularly in volleyball or structured exercise.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Group 1: Volleyball Players With Crossed Eye-Hand Dominance	Other: Volleyball Players With Crossed Eye-Hand Dominance; Volleyball players whose dominant eye and dominant hand are on opposite sides of the body. For example, right-eye dominance with left-hand dominance or left-eye dominance with right-hand dominance. Participants will undergo upper extremity muscle strength and motor performance assessments. No intervention will be administered.
Group 2: Volleyball Players Without Crossed Eye-Hand Dominance	Other: Volleyball Players Without Crossed Eye-Hand Dominance; Volleyball players whose dominant eye and dominant hand are on the same side of the body. For example, right-eye dominance with right-hand dominance or left-eye dominance with left-hand dominance. Participants will undergo the same upper extremity muscle strength and motor performance assessments. No intervention will be administered.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dominant Eye	Eye dominance will be determined using the Miles Test. The participant will focus on a distant target with both eyes open and will then close each eye separately. The eye with which the target remains centered will be classified as the dominant eye. Eye dominance will be used with hand dominance to classify participants as having crossed or non-crossed eye-hand dominance.	4 weeks
Bilateral Shoulder Muscle Strength	Bilateral shoulder flexion, extension, and abduction muscle strength will be measured using a validated handheld myometer. Measurements will be recorded separately for the right and left sides. Higher force values indicate greater shoulder muscle strength, whereas lower values indicate lower muscle strength.	4 weeks
Bilateral Elbow Muscle Strength	Bilateral elbow flexion and extension muscle strength will be measured using a validated handheld myometer. Measurements will be recorded separately for the right and left sides. Higher force values indicate greater elbow muscle strength, whereas lower values indicate lower muscle strength.	4 weeks
Bilateral Handgrip Strength	Handgrip strength will be measured bilaterally using a digital hand dynamometer. Three measurements will be performed for each hand, and the mean value will be recorded. Higher values indicate greater handgrip strength, whereas lower values indicate lower handgrip strength.	4 weeks
Hand-Eye Coordination	Hand-eye coordination will be assessed using the Alternate-Hand Wall Toss Test. The participant will throw a ball against a wall with one hand, catch it with the opposite hand, and repeat the sequence by alternating hands. The total number of successful throws and catches completed within 30 seconds will be recorded. A higher number indicates better hand-eye coordination and motor performance, whereas a lower number indicates poorer performance.	4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Medicine Ball Throw Distance	Upper extremity explosive power will be assessed using the Medicine Ball Throw Test. The participant will sit with the back supported against a wall and the legs extended and will throw the medicine ball as far as possible. The longest valid throwing distance will be recorded in meters. A longer distance indicates greater upper extremity explosive power.	4 weeks
Closed Kinetic Chain Upper Extremity Stability Test Score	Upper extremity functional stability, strength, power, and endurance will be assessed using the Closed Kinetic Chain Upper Extremity Stability Test. The participant will assume a push-up position with the hands placed on two markers positioned 90 centimeters apart. The total number of valid alternating touches performed within the specified test period will be recorded. A higher number of touches indicates better upper extremity functional performance and stability.	4 weeks
Scapular Muscular Endurance Time	Scapular stabilizer muscle endurance will be assessed using the Scapular Muscular Endurance Test. An appropriately sized wooden rod will be positioned between the participant's elbows while the scapulae are maintained in a neutral position. The duration for which the participant can maintain the standardized position will be recorded in seconds. A longer duration indicates greater scapular muscular endurance.	4 weeks
Upper Quarter Y-Balance Test Reach Distance	Upper extremity and trunk balance, mobility, and stability will be assessed using the Upper Quarter Y-Balance Test. Testing will begin with the non-dominant hand as the reaching hand. Maximum reach distances in the medial, inferolateral, and superolateral directions will be recorded. Greater reach distances and higher composite scores indicate better upper extremity dynamic balance and functional stability.	4 weeks
Light-Based Reaction Time	Reaction time and neuromuscular control will be assessed using the BlazePod light-based reaction system. Participants will respond to randomly activated visual stimuli according to a standardized testing protocol. Reaction time will be recorded in milliseconds. A shorter reaction time indicates faster visual-motor responses, whereas a longer reaction time indicates slower responses.	4 weeks

Collaborators and Investigators

• Sponsor: Istinye University

Study record dates

Study Major Dates

• Study Start (Estimated): August 30, 2026
• Primary Completion (Estimated): November 15, 2026
• Study Completion (Estimated): November 30, 2026

Study Registration Dates

• First Submitted: August 21, 2026
• First Submitted That Met QC Criteria: August 21, 2026
• First Posted (Actual): August 25, 2026

Study Record Updates

• Last Update Posted (Actual): August 25, 2026
• Last Update Submitted That Met QC Criteria: August 21, 2026
• Last Verified: August 1, 2026

More Information

Terms related to this study

• Keywords: Upper Extremity Performance; Volleyball Players; Eye-Hand Dominance
• Other Study ID Numbers: 2026/01

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No