Validity and Reliability of the L Test in Geriatric Individuals

Background Functional mobility declines significantly with aging due to sarcopenia, reduced neuromuscular coordination, impaired balance, and slower gait speed. These changes contribute to increased fall risk, reduced independence, and diminished quality of life in older adults. Accurate assessment tools are essential for identifying early functional deterioration, planning individualized rehabilitation interventions, and monitoring clinical outcomes.

Commonly used functional tests such as the TUG and 10MWT measure important aspects of mobility; however, they do not fully represent the complexity of real-life movement patterns. Daily activities often require multidirectional walking, pivoting, turning, and completing longer paths that challenge balance and coordination.

The L Test is a modification of the TUG and incorporates: Sit-to-stand, straight walking, turning, extended pathway walking, returning and sitting. This structure more closely resembles real-world functional mobility demands. Previous studies in clinical groups, including Parkinson's disease and chronic obstructive pulmonary disease, have demonstrated strong reliability (ICC > 0.90) and significant correlations with TUG and gait speed tests. However, no studies have systematically examined the psychometric properties of the L Test among healthy older adults.

Given the progressive aging of the population and the increasing need for precise mobility assessments, establishing the reliability and validity of the L Test in geriatric individuals is clinically important.

Objectives: The primary objective is to determine the test-retest reliability of the L Test. Secondary objectives include: Determining concurrent validity against TUG and 10MWT Calculating measurement error (SEM, MDC) Contributing to clinical decision-making by identifying cutoff values for functional mobility.

Study Design and Setting: This is a single-center, observational methodological study conducted at: Hasan Kalyoncu University Medical Research and Application Center, Gaziantep, Türkiye.

Participants will be assessed twice at a one-week interval to evaluate test-retest reliability and measurement consistency.

Participants and Sample Size: A total of 70 participants will be recruited.

Inclusion criteria

≥65 years Able to understand instructions Able to walk independently (with or without minimal assistive device) MMSE ≥24 No acute medical condition

Exclusion criteria

Lower-limb surgery within 6 months Diagnosed neurological or cardiopulmonary disease Visual or auditory impairments preventing safe assessment.

Study Procedures

• Informed Consent and Baseline Assessments: Participants will receive verbal and written explanations about the study. After informed consent: Demographic data will be recorded.Height, weight, BMI, chronic diseases, use of assistive devices documented
• Functional Tests:All tests will be administered by trained physiotherapists. L Test Procedure:Starting seated in a standard chair. Standing up upon instruction. Walking 3 m straight. Turning left and walking 7 m. Returning via the same route. Sitting down again. Total distance: 20 m. Time recorded using a stopwatch

TUG Test:Standing from a chair. Walking 3 m, turning, returning, and sitting. Time recorded.

10MWT: Walking a 14-m walkway (10-m timed zone). Three trials at normal and fast speed. Average used for analysis

• Retesting: The full test battery will be repeated 1 week later under identical conditions.

Outcome Measures

Primary Outcome:

L Test completion time (seconds) Secondary Outcomes TUG time 10MWT time SEM MDC Correlation between L Test and other mobility tests.

Data Management and Analysis: Data will be stored securely with coded identifiers, complying with national data protection regulations.

Statistical Analysis Plan:

ICC (2,1) for test-retest reliability Pearson correlation for concurrent validity SEM = SD × √(1 - ICC) MDC = SEM × 1.96 × √2 Descriptive statistics for demographic variables p < 0.05 considered statistically significant

Ethics, Safety, and Monitoring:

Ethical approval has been obtained All procedures follow the Declaration of Helsinki Trained physiotherapists will supervise tests to prevent falls Participants may withdraw at any time Adverse events (if any) will be documented and reported

Expected Impact This study is expected to: Provide the first comprehensive psychometric evaluation of the L Test in healthy older adults. Offer clinicians a valid and reliable tool for mobility screening. Support risk stratification for falls and mobility limitations. Guide clinical decision-making in geriatric rehabilitation.

Dissemination Plan Results will be submitted to: Peer-reviewed journals, National and international physiotherapy and geriatric conferences. Participants may request a summary of the study results.

Inclusion criteria

• ≥65 years
• Able to understand instructions
• Able to walk independently (with or without minimal assistive device)
• MMSE (Mini Mental State Examination) ≥24
• No acute medical condition

Exclusion criteria

• Lower-limb surgery within 6 months
• Diagnosed neurological or cardiopulmonary disease
• Visual or auditory impairments preventing safe assessment