The purpose of this study is to investigate the immediate effects of a mental practice technique, called Physical, Environment, Task, Timing, Learning, Emotion, Perspective (PETTLEP)-based Action Observation and Motor Imagery (AOMI), on arm movement in stroke survivors. Stroke often causes difficulty in moving the arm smoothly, leading patients to compensate by using their back or shoulder. In this study, participants will either receive a single session of the AOMI training (watching and mentally practicing a reach-to-grasp movement) or a control relaxation task. The researchers will use a smartphone-based motion capture system (OpenCap) to measure if the mental practice immediately improves the smoothness of the arm movement and reduces compensatory body movements.

This study employs a single-blind, pretest-posttest, prospective randomized controlled trial design to evaluate the acute effects of a single session of Physical, Environment, Task, Timing, Learning, Emotion, Perspective (PETTLEP)-based Action Observation and Motor Imagery (AOMI) in stroke patients. Following a stroke, patients often develop pathological movement patterns and maladaptive compensatory strategies, such as trunk displacement or shoulder girdle elevation, due to impaired motor commands. Traditional task practice requires voluntary motor output that many severely impaired patients lack. Motor imagery combined with action observation offers a cognitive simulation alternative that activates neural motor planning circuits.

A total of 28 eligible stroke survivors will be randomized in a 1:1 ratio into an experimental (AOMI) group or a control (cognitive and somatic) group. Baseline kinematics of a standardized Reach-to-Grasp task will be recorded using OpenCap, a markerless 3D motion capture system utilizing smartphone cameras.

The intervention consists of three blocks lasting approximately 25 minutes in total. The experimental group will engage in a scaffolded AOMI protocol using a 1:3 physical-to-mental practice ratio. This includes sensory priming (holding the target object), action observation (watching a 1st-person video of the task), and selective motor imagery with specific constraints targeting movement smoothness and the inhibition of compensatory trunk and shoulder movements. The control group will perform matched-duration non-motor tasks, including body scanning and visuospatial navigation.

Immediately following the intervention, the reach-to-grasp task will be re-assessed using the OpenCap system to quantify short-term changes in movement smoothness (Number of Velocity Peaks), trunk displacement, and shoulder girdle elevation.

Inclusion Criteria:

• Female and male adults aged 40 to 80 years with a diagnosis of unilateral ischemic or hemorrhagic stroke.
• Residual voluntary movement activity of the affected upper limb.
• Mild to moderate spasticity (Modified Ashworth Scale ≤ 3).
• Adequate cognitive function to understand and follow verbal instructions (Mini-Mental State Examination ≥ 21).
• Medically stable patients, with no active or uncontrolled systemic illness.
• Ability to sit unsupported for at least 30 minutes and be able to perform brief cognitive-motor exercises.

Exclusion Criteria:

• Other central nervous system disorders (e.g., Parkinson's disease, multiple sclerosis, traumatic brain injury).
• Musculoskeletal or orthopedic conditions causing restriction of movement in the upper-limb (such as fixed contractures, severe joint deformities, shoulder subluxation).
• Severe sensory deprivation, visual neglect, or inattention that interferes with completion of the task or the ability to engage in motor imagery.
• Uncontrolled seizures, severe cardiovascular instability, or any other contraindication to imagery.

Individual participant data (IPD) will not be shared to ensure the strict privacy and confidentiality of the stroke survivors participating in this study. The data collected involves specific clinical and kinematic assessments conducted for an academic Master's thesis. The informed consent obtained from participants covers the use of their data for this specific research project and allows for publication in aggregate form only. It does not explicitly grant permission for open public data sharing. Therefore, only summary and aggregate data will be reported in the final thesis and any resulting peer-reviewed publications.

Single-blind study