GYKO-Based L-Test Reliability in Parkinson's Disease

January 20, 2026 updated by: Büşra Akıncı, Hasan Kalyoncu University

Test-Retest and Interrater Reliability and Validity of Postural Sway Parameters Measured With GYKO During the L Test in Individuals With Parkinson's Disease

This study aims to investigate the interrater and test-retest reliability of GYKO-based postural sway measurements collected during the L-Test and Timed Up and Go (TUG) test in individuals with Parkinson's disease (Hoehn & Yahr stages 1-3). Two independent raters will perform GYKO-based assessments of the L-Test and TUG with a 20-minute interval. Participants will return one week later to repeat the same procedures for test-retest reliability. Concurrent validity will be examined using the Berg Balance Scale.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

This study aims to investigate the test-retest and interrater reliability, as well as the concurrent validity, of GYKO-based postural sway measurements obtained during the L-Test and the Timed Up and Go (TUG) test in individuals with Parkinson's disease. Participants diagnosed with idiopathic Parkinson's disease (Hoehn & Yahr stages 1-3) will be evaluated using the GYKO inertial measurement unit, which provides quantitative postural sway parameters including ellipse area, mean length, mediolateral and anteroposterior mean length, mediolateral and anteroposterior mean distance, and velocity.

Two independent raters will perform GYKO-based assessments of the L-Test and TUG on the same day, with a 20-minute interval between raters, to determine interrater reliability. Participants will return one week later to repeat the same procedures, allowing assessment of test-retest reliability.

To examine concurrent validity, participants' functional balance will also be assessed using the Berg Balance Scale, and correlations between GYKO variables and clinical mobility tests (L-Test and TUG) will be analyzed.

Study Type

Observational

Enrollment (Estimated)

25

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Turkey (Türkiye)
    • Şahinbey
      • Gaziantep, Şahinbey, Turkey (Türkiye), 27000
        • Hasan Kalyoncu University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Individuals aged 50-85 years with idiopathic Parkinson's disease (Hoehn & Yahr stages 1-3) who can walk independently and participate in TUG, L-Test, and GYKO assessments.

Description

Inclusion Criteria:

  • Diagnosis of idiopathic Parkinson's disease
  • Hoehn & Yahr stage 1-3
  • Ability to walk independently with or without an assistive device
  • Ability to follow verbal instructions
  • Age 50-85

Exclusion Criteria:

  • Other neurological, vestibular, or musculoskeletal disorders affecting balance
  • Deep brain stimulation (DBS) implant
  • Severe visual or auditory impairment

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Parkinson's disease group
Parkinson's disease patients with stage 1-3 hoehn yahr
Other: GYKO-Based Postural Sway Assessment

This procedure involves obtaining postural sway parameters using the GYKO inertial measurement device during the Time Up and Go (TUG) test and L-Test. No therapeutic intervention is applied.

Time Up and Go Test: Timed Up and Go (TUG) is a standardized functional mobility test used to assess dynamic balance and gait performance. Participants are instructed to stand up from a standard-height chair, walk 3 meters, turn around, walk back to the chair, and sit down. The total time to complete the task (in seconds) is recorded. Higher times indicate reduced mobility.

L Test: Time (in seconds) to complete the L-Test of Functional Mobility. The test requires participants to stand up from a chair, walk 3 m, execute a 90° turn, walk another 7 m, perform a 180° turn, and return along the same path (total walking distance ≈ 20 m). The task ends when the participant sits back down. The total time to complete the task (in seconds) is recorded. Higher times indicate reduced mobility.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Interrater Reliability of GYKO-Based Postural Sway Parameters
Time Frame: Day 1

Interrater reliability of postural sway will be evaluated using a composite set of parameters derived from GYKO inertial sensor data collected during the Timed Up and Go (TUG) and L-Test procedures. Measurements will be obtained independently by two raters on the same day.

The composite postural sway outcome includes ellipsoid area, displacement-related parameters in the mediolateral and anteroposterior directions, and velocity-related parameters. Although individual variables are expressed in different units, all parameters collectively represent a single postural control construct.

Interrater reliability will be assessed using the intraclass correlation coefficient (ICC 2,1) with 95% confidence intervals.
Day 1
Test-Retest Reliability of GYKO-Based Postural Sway Parameters
Time Frame: 1 week

Test-retest reliability of postural sway will be assessed using a composite set of parameters derived from GYKO inertial sensor data collected during the Timed Up and Go (TUG) and L-Test procedures. Participants will be re-evaluated after a 1-week interval.

The composite postural sway outcome includes ellipsoid area, mediolateral and anteroposterior displacement parameters, and velocity-related parameters, representing a single postural control construct.

Test-retest reliability will be analyzed using the intraclass correlation coefficient (ICC 3,1) with 95% confidence intervals. Paired t-tests will be used to examine differences between test and retest measurements.
1 week

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Validity of GYKO Postural Sway Parameters with Functional Mobility (TUG and L-Test)
Time Frame: Day 1

Concurrent validity will be examined by analyzing the relationship between the composite GYKO-based postural sway parameters obtained during the Timed Up and Go (TUG) and L-Test procedures and functional mobility performance.

Pearson correlation coefficients will be used to assess the associations between postural sway composite outcomes and TUG and L-Test completion times.
Day 1
Relationship Between Postural Sway and Balance Performance (Berg Balance Scale)
Time Frame: Day 1
Balance performance will be assessed using the Berg Balance Scale at baseline. The relationship between Berg Balance Scale scores and the composite GYKO-based postural sway parameters obtained during the Timed Up and Go (TUG) and L-Test procedures will be analyzed using Pearson correlation coefficients.
Day 1
L test and TUG Completion Time
Time Frame: 1 week

Functional mobility will be assessed using the Timed Up and Go (TUG) test and the L-Test. The TUG requires participants to stand up from a chair, walk 3 meters, turn, return, and sit down.

The L-Test is a modified version of the TUG and consists of standing up from a chair, walking 3 meters, performing a 90° turn, walking an additional 7 meters, performing a 180° turn, and returning along the same path (total walking distance approximately 20 meters).

The time required to complete each test will be recorded in seconds.
1 week

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hasan Kalyoncu University

Investigators

  • Study Chair: Büşra Akıncı, MSc, Hasan Kalyonuc University
  • Principal Investigator: Saadet Nur Çörekçioğlu, P.T., Hasan Kalyoncu University
  • Study Director: Günseli Usgu, Assoc. Prof., Hasan Kalyoncu University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 1, 2025

Primary Completion (Estimated)

April 1, 2026

Study Completion (Estimated)

May 1, 2026

Study Registration Dates

First Submitted

December 8, 2025

First Submitted That Met QC Criteria

December 25, 2025

First Posted (Actual)

January 8, 2026

Study Record Updates

Last Update Posted (Actual)

January 21, 2026

Last Update Submitted That Met QC Criteria

January 20, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • HKU/PH/2

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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