Investigating the Validity and Reliability of the L Test in Geriatric Individuals
Investigating the Validity and Reliability of the L Test in Geriatric Individuals
Age-related declines in mobility, gait speed, balance, and functional independence are major determinants of morbidity and fall risk among older adults. Widely used functional mobility assessments-such as the Timed Up and Go Test (TUG) and the 10-Meter Walk Test (10MWT)-provide valuable information but do not fully capture the multidimensional motor tasks required in daily life, such as turning, directional changes, sit-to-stand transitions, and combined mobility tasks. The L Test, originally developed as an expanded form of TUG, includes turning, curved-path walking and a longer walking distance, and may therefore offer a more comprehensive assessment of functional mobility. Although previous studies have demonstrated high test-retest reliability and significant correlations with TUG in clinical populations such as Parkinson's disease and chronic conditions, evidence regarding the reliability and validity of the L Test in healthy geriatric individuals is lacking. This study aims to address this gap by evaluating the psychometric properties of the L Test in older adults.
Purpose: The purposes of the study are to: Evaluate the test-retest reliability of the L Test in geriatric individuals. Determine its concurrent validity by examining relationships with TUG and 10MWT. Calculate measurement error indices including Standard Error of Measurement (SEM) and Minimal Detectable Change (MDC).
Hypotheses H1: The L Test is a valid assessment tool for older adults. H2: The L Test demonstrates acceptable test-retest reliability (ICC ≥ 0.70). H3: The L Test shows a strong correlation with TUG (r ≥ 0.50). H4: The L Test shows a strong correlation with 10MWT (r ≥ 0.50).
Study Design: A cross-sectional methodological study with repeated measures (test-retest) one week apart.
Participants: Target population: Adults aged ≥65 years who can independently ambulate at least 10 meters.
Sample size: 58 participants based on power analysis; increased to 70 to compensate for potential attrition.
Sampling: Simple random sampling.
Inclusion Criteria:
≥65 years of age Mini-Mental State Examination ≥24 Able to walk 10 meters independently Voluntary participation
Exclusion Criteria:
Lower limb surgery within the past 6 months Diagnosed cardiovascular, neurological, or pulmonary disease Visual or auditory impairments affecting test safety
Procedures Participants will complete: L Test, Timed Up and Go Test (TUG), 10-Meter Walk Test (10MWT; normal and fast speed). One week later, all assessments will be repeated under the same conditions.
Outcome Measures: Primary: L Test time (seconds)
Secondary:TUG time, 10MWT time (normal and fast pace), SEM and MDC values. Pearson correlation with TUG and 10MWT
Statistical Analysis:
Test-retest reliability: ICC Concurrent validity: Pearson correlation coefficient Measurement error: SEM, MDC Significance level: p < 0.05
Ethical Considerations: All tests conducted by trained physiotherapists. Continuous supervision to minimize fall risk. Written informed consent obtained. Participants may withdraw at any time. Confidentiality ensured
Expected Outcomes: The study is expected to:
Provide normative data for the L Test in the geriatric population Demonstrate the test's psychometric robustness Support the clinical use of the L Test for functional mobility screening Contribute to physiotherapy and geriatric rehabilitation literature
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
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
3. 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:
Exclusion Criteria: