Introduction Stroke remains the third leading cause of death and disability combined. Post-stroke cognitive impairment (PSCI) is a common neurological sequela that may affect up to 80% of stroke survivors. Several systematic reviews and studies indicated that Tai Chi benefits patients with mild cognitive impairment, leading to significant improvement in cognitive function.

Our previous study adopted a tailored sitting Tai Chi programme for the rehabilitation of subacute stroke survivors without any cognitive impairment. The results of the randomised controlled trial (RCT) showed that upper limb function, balance control, ADL, depressive symptoms, and QoL were significantly improved compared to the control group. To better understand the usefulness of the sitting Tai Chi programme for chronic stroke survivors with cognitive impairment and how it might affect other rehabilitation outcomes, this study was proposed to examine its feasibility and preliminary effectiveness.

Methods An outcome assessor-blinded RCT will be conducted. Participants will be randomised with a 1:1 allocation ratio to either the intervention group or the waiting list control group. A total number of 88 dyads (176 participants) including 44 stroke survivors and 44 caregivers will be recruited in each group.

For the qualitative part, a purposive sample of 30 stroke survivors with low, medium and high satisfaction scores will be invited.

Intervention Sitting Tai Chi group: Participants in the sitting Tai Chi group will receive 12 weeks of 10-form sitting Tai Chi exercise training with a frequency of three days a week and 40 minutes a day, including 5 minutes warm-up, 30 minutes Tai Chi training, and 5 minutes cool-down. A registered nurse (RN) with experience with Tai Chi training and who participated in our previous study will lead the training session. The RN will receive refresher training in sitting Tai Chi and learn the basics about the condition of PSCI and the characteristics of survivors with PSCI.

Control group: Participants in the control group will receive usual care. That is, regular inpatient treatment and care, without additional rehabilitation treatment. At the end of the intervention follow-up assessment, they will be invited to participate in the sitting Tai Chi exercise led by the same nurse as well.

Assessment and measurement Primary outcomes include cognitive function, upper limb function, balance control, and depressive symptoms. They will be assessed at baseline, eight weeks, and 12 weeks after the commencement of the sitting Tai Chi training by validated scales.

1. Cognitive function will be measured using the MoCA scale.
2. Upper limb function will be measured using Fugl-Meyer Test Upper Limb section and Wolf Motor Function Test
3. Balance control will be measured using the Berg Balance Scale and the Trunk Impairment Scale
4. Depressive symptoms will be measured by the 15 items Geriatric Depression Scale short form.
5. The Modified Barthel Index will be used to assess ADL.
6. QoL will be assessed using the Chinese version of Stroke-Specific Quality of Life Scale.

Feasibility and Acceptability This pilot RCT evaluates the feasibility of the sitting Tai Chi programme. Feasibility is evaluated based on recruitment and retention rates from baseline to follow-up. All participants will be invited to fill in a satisfaction survey with the sitting Tai Chi programme and the usefulness of its components.

Satisfaction A self-developed User Satisfaction Questionnaire (USQ) will be used to assess stroke survivors' satisfaction in terms of usability, acceptability, and applicability.

Adverse events measurements Any unexpected adverse events during the intervention period will be monitored. Semi-structured interview We will conduct semi-structured in-depth interviews using a pre-designed semi-structured interview guide.

Ethical considerations Ethical approval will be applied from the Joint Chinese University of Hong Kong- New Territories East Cluster Clinical Research Ethics Committee and the study hospital's research ethics committee. Written consent will be obtained from the eligible participants.

Data collection, consent, and sample storage A sociodemographic and clinical data sheet will be used to record the corresponding information. The research assistants will screen potentially eligible participants by daily reviewing the medical records of all stroke survivors admitted to the study venues.

Data processing and analysis Statistics analysis will be conducted using the IBM SPSS version 29.0. All primary analyses will be conducted on an intention-to-treat basis. Descriptive statistics will be used. A generalized estimating equations (GEE) model will be employed to compare differential change of each of the primary and secondary outcomes across the study time points between the two groups.

Content analysis will be used to analyse the qualitative data from the participants.

Inclusion Criteria for stroke patients:

- Individuals who meet the following criteria will be recruited: i. aged 18 years or above; ii. have been admitted to a hospital with a clinical diagnosis of first or recurrent ischaemic or haemorrhagic stroke, and meet the diagnostic criteria of PSCI (classified according to DSM-5 criteria); iii. in the chronic stage of stroke; iv. MoCA score: 19-25 (two points are added if the individual has ≤ 6 years of education; one point is added if the individual has > 6 and ≤ 12 years of education, no points are added for the individual with > 12 years of education); v. be able to sit independently with or without sitters; vi. be able to use and raise at least one arm while sitting (upper extremity muscle strength ≥ Ⅲ); vii. have a primary caregiver (a paid or unpaid person who provides most assistance to the stroke survivor); viii. be able to communicate in Chinese and provide informed consent; ix. is currently hospitalised in this geriatric rehabilitation ward and unlikely to be discharged within 3 months.

Exclusion Criteria for stroke patients:

• Individuals will be excluded if other causes of cognitive impairment are present, such as Alzheimer's disease, acquired immune deficiency syndrome, a National Institutes of Health Stroke Scale (NIHSS) score >16, severe hearing or visual impairment, severe complications following a stroke (e.g., limited comprehension and receptive aphasia, venous thrombosis), a history of severe medical conditions or current serious illnesses (e.g. myocardial infarction, use of a cardiac pacemaker or a defibrillator, organ failure, malignancy, mental diseases, other neurological diseases such as multiple sclerosis or Parkinson's disease, having received thrombolytic therapy or surgery, joint replacement surgeries or fractures within the past six months), pregnant or lactating women; prior regular (at least three times/week) Tai Chi practice or other mind-body exercises (e.g., Yoga, Qigong, Ba Duanjin, or mindfulness training) within the past six months; and those participating in other clinical trials that might influence this study.

Inclusion criteria for caregivers:

i. age ≥ 18 years; ii. be able to communicate in Chinese and provide informed consent; iii. medically stable and physically able to provide support.

Exclusion criteria for caregivers:

i. impaired cognitive functions (Abbreviated Mental Test, AMT ≤ 7); ii. being a medical resident/trainee or a physical therapist; iii. having prior regular (at least three times/week) Tai Chi practice or other mind-body exercises (e.g., Yoga, Qigong, Ba Duanjin, or mindfulness training) within the past six months; iv. participating in other clinical trials that might influence affect this study.

The data could be shared basing on reasonable request.