Measurement Properties of the Walking Adaptability Ladder Test and Foot Tap Test in Multiple Sclerosis

Walking and motor control impairments are among the most common manifestations experienced by people with multiple sclerosis (pwMS) and may already be present in individuals with mild disability. Subtle changes in walking performance can reflect early disease progression, highlighting the need for sensitive clinical outcome measures that capture complex, real-world mobility. Commonly used assessments primarily quantify time or distance and may lack sensitivity to detect early or subtle functional changes in daily-life walking. Successful everyday mobility requires gait adaptability, defined as the ability to continuously adjust walking patterns in response to environmental or task-related challenges, including the processing of external perturbations and internal factors such as fatigue, balance confidence, and fear of falling. Despite its clinical relevance, gait adaptability is not specifically addressed by currently validated clinical tests in pwMS. The Walking Adaptability Ladder Test (WALT), which challenges the interaction between step length, cadence, and walking speed through continuous adjustments, and the Foot Tap Test (FTT), which assesses lower limb motor control and rhythmic coordination, have demonstrated promising measurement properties in other populations but have not yet been evaluated in pwMS. The primary aim of this study is to examine the test-retest reliability and construct validity of the WALT and FTT in pwMS with mild disability. Secondary aims include evaluating the measurement properties of the Balance Recovery Scale and the Gait-Specific Attention Scale in pwMS with mild disability, identifying inertial measurement unit-derived metrics that best discriminate pwMS with low disability from healthy controls, and exploring whether relationships between clinical motor test outcomes and self-reported measures provide complementary insights into subtle gait impairments.