The goal of this clinical trial is to investigate the acute effects of immersive virtual reality (VR)-based exergaming combined with transcranial direct current stimulation (tDCS) on executive functions in healthy older adults. The main questions it aims to answer are:

• Does VR-based exergaming combined with tDCS improve executive function performance in healthy older adults compared with a control condition?
• Do single interventions (tDCS alone or VR-based exergaming alone) improve executive function performance compared with the control condition?
• Does the combined intervention produce greater improvements in executive function performance than either intervention alone? Researchers will compare four intervention conditions to evaluate differences in executive function performance following each session.

Participants will:

• Complete four intervention sessions in a randomized crossover sequence, with a washout period of at least 7 days between sessions
• Receive the following intervention conditions:
• sham-tDCS + VR-video
• tDCS + VR-video
• sham-tDCS + VR-exergaming
• tDCS + VR-exergaming
• Complete executive function assessments immediately after each session, including:
• the Flanker task for inhibitory control
• the more-odd shifting task for cognitive flexibility
• the Corsi block-tapping task for working memory

Inclusion Criteria:

(1) Age between 60 to 70 years old; (2) Right-handed (Edinburgh Handedness Inventory (Chinese version) > 40); (3) Normal overall cognitive function (Montreal Cognitive Assessment (Beijing version) ≥ 26).

Exclusion Criteria:

(1) Musculoskeletal injury; (2) neurological/neurodegenerative disorders (e.g., Alzheimer's disease); (3) history of brain infections or cerebrovascular diseases; (4) psychiatric disorders (e.g., major depressive disorder, schizophrenia); (5) unstable or chronic medical conditions (e.g., cardiac disease, seizures (personal/family history)); (6) hearing and visual impairments (e.g., color blindness and conditions severely affecting the ability to see the screen or distinguish colors); (7) metal implants (e.g., pacemakers); (8) brain stimulation or exercise training intervention within the past 6 months; (9) failure to meet safety criteria for brain stimulation (e.g., pregnancy)