In Group A (intervention), the 12 participants will form 2 groups (6 participants per group) according to their individual exercise intensity levels determined prior to the intervention for each participant. Each group will receive online coach-supervised training sessions 3 times per week for 4 weeks (a total of 12 sessions), which will be delivered by a certified coach and an assistant (a student helper, major in sports and health). Each session will consist of warm-up, aerobic exercise, resistance exercise, stretching and cool-down, with exercise period progressively increasing from 30 minutes to 50 minutes and exercise intensity progressively increasing from low to moderate levels (Table 1). Lighter intensity may be adopted when there is a need (e.g., for those with severe conditions). Target heart rate during exercise will be monitored by a pulse oximeter. Cameras will be requested to be turned on all the time.

Participants in Group B (active control) will receive an essay on exercise and health every week for four weeks (a total of 4 essays). Proposed topics include: 1) beneficial effects of exercise and recommended exercise for breast cancer survivors; 2) WHO's recommendations for physical activity; 3) exercise intensity; 4) principles of exercise.

It is a prospective and pilot study of RCT. It will be a pilot to test acceptability and feasibility of a two-armed tele-exercise RCT to mitigate symptoms and improve health for breast cancer survivors. In this study, outcome assessors and data analysts will be masked from the allocation results. The pilot will recruit 24 patients and randomly assign them to an intervention group (Group A) and an active control group (Group B). All participants in both groups will continue receiving usual care from the study hospital during the study period. Additionally, those in Group A (intervention) will receive the tele-exercise (12 home-based online training sessions + 4 psychological counselling sessions), while those in Group B (active control) will receive 4 essays on exercise and health. Outcome measurements will be repeatedly performed before and after the intervention.

Participants rated intervention regarding the aspects of satisfaction, enjoyment, perceptions of safety, difficulty, tolerability of treatment, adverse events using a 5-Liker questionnaire, mean score was used to assess, and higher score indicates greater acceptability.

Participants rated intervention regarding the aspects of satisfaction, enjoyment, perceptions of safety, difficulty, tolerability of treatment, adverse events by interviews.

The proportion of eligible participants who are enrolled at baseline of the study.

The proportion of enrolled participants who are present throughout the full length of the treatment.

The proportion of total sessions offered to participants to the actual number of sessions participants attended.

Participants' level of adherence to the content, frequency, duration, and coverage of the treatment as delivered by the research team. Assessed by percentage of participants who complied with intervention procedures.

estimated by the 6-minute walk test, primary outcome of the main study

upper extremity muscle strength by the hand grip test and lower extremity muscle strength by the timed stand test