Acute Effect of Exergaming Based Sitting Tai Chi

Inclusion Criteria: * Are aged 18-30 years (young adult group) or 60-75 years (older adults) * Have no current regular participation (e.g., ≥1 session/week) in Tai Chi, martial arts, or other mind-body exercise (e.g., yoga or qigong) in the last 3-6 months * Have no self-reported or clinically documented history of mild cognitive impairment, dementia, or other neurological (e.g., stroke) or psychiatric disorders (e.g., schizophrenia) known to affect cognition * Score within the normal range on the Hong Kong version of Montreal Cognitive Assessment (HK-MoCA) based on established age- and education-adjusted cutoffs * Are medically stable, with or without controlled chronic conditions (e.g., controlled hypertension or diabetes) * Are able to tolerate light-to-moderate seated exercise (Chinese version of Physical Activity Readiness Questionnaire score = 0) * Have no significant sensory impairment (e.g., vision) not corrected by assistive devices (e.g., glasses) * Are not engaged in regular structured exercise involving moderate-to-vigorous intensity physical activity (e.g., brisk walking, running, or racquet sports) more than two times per week over the preceding three months * Are able to communicate in Chinese (Moved from Exclusion for clarity) Exclusion Criteria: * Have medical conditions that may interfere with safe participation, including pacemaker implantation or prosthetic devices * Have serious orthopedic or cardiovascular disorders that could affect participation in exergaming training * Have significant motor or balance impairment that would prevent performing basic seated arm and trunk movements * Are currently undergoing other clinical trials or structured exercise or cognitive training programmes \>2 times/week during the preceding three months