Dose-Response and Phase-Specific Effects of Graded Cognitive Load on Functional Mobility in Older Adults: A Kinematic Analysis

Inclusion Criteria: * Age ≥ 60 years * Ability to ambulate independently without assistive devices * Ability to follow verbal instructions and perform dual-task activities * Medically stable and capable of participating in functional mobility assessment Cognitive function within normal range, defined as Mini-Mental State Examination (MMSE) score ≥ 24 out of 30, indicating absence of significant cognitive impairment . * Functionqal independence in basic activities of daily living, defined as Barthel Index score ≥ 90 out of 100 * Body Mass Index (BMI) between 18.5 and 29.9 kg/m², as values ≥ 30 kg/m² (obesity) may adversely affect gait and balance performance. Exclusion Criteria: * Any neurological disease that affects walking or balance, such as stroke or Parkinson's disease * Any musculoskeletal condition that limits lower-limb movement or affects normal walking patterns * Severe cognitive impairment defined as Mini-Mental State Examination (MMSE) score \< 24 * Visual, vestibular, or hearing problems that affect safe walking or balance control * History of lower-limb injury or surgery within the last 6 months * Serious medical conditions that make participation unsafe, such as unstable cardiac or respiratory disease