In the past few years, Branched Chain Amino Acid (BCAA) supplements have gradually used on different groups. From training athletes, maintaining functions of healthy elders to preventing disabilities of people that can't do intense exercises. BCAAs are now considered to be able to prevent muscle atrophy and strength loss, also possible to increase strength and muscle mass if combined with resistance exercises. Stroke patients have difficulties with moving, which led to multiple disabilities, are more likely to have sarcopenia and strength loss. Furthermore, reducing the will of moving or walking. Recently, studies showed that combined BCAAs with resistance exercises can effectively increase muscle mass, thus commonly used on training athletes.

Although aerobic exercises are proven to be more likely to improve walking ability of chronic stroke patients than traditional rehabilitation, BCAAs' effects are yet to be proven. Therefore, the aim of this study is to explore if BCAAs combined with moderate intensity exercises can prevent muscle atrophy, loss of strength and cardiopulmonary function.

This is a randomized control trial. Participants are randomly assigned to either experiment or control groups. Both group received aerobic exercise (30 min in a session, 3 days a week, and for 8 weeks). Experiment group received BCAA supplement immediately after the exercise while the control group receive sham product (vitamins). The outcome measurements (including muscle mass, functional measures, and quality of life) are performed before (0-wk) and after (8-wk) the interventions, also after interventions in 3 months and 6 months for follow up.

Setting : inpatient rehabilitation department of Wan-Fang Hospital and Shuang-Ho Hospital Study population : Patients received inpatient treatment or rehabilitation for stroke in Wan-Fang Hospital (WFH) and Shuang-Ho Hospital (SHH).

Study design: controlled trial with randomization Blinding : The patients were blinded by the real or sham bcaa supplements. The assessors who performed the outcome measurements were blinded to the assignment of treatment.

Measurements : DXA(Dual-energy X-ray absorptiometry),CPET(Cardiopulmonary Exercise Testing),6 minute walk test,Timed up and go,Berg balance test,Stroke Specific Quality of Life Scale (SS-QOL).

These measurements (including the clinical and corticomotor excitability assessments) are performed by one researcher who are responsible for the measurements.

Compliance and side effect. The compliance of supplements were investigated. The attendance of treatments (including bcaa supplements and physical therapy sessions) and possible side effect/discomfort were recorded during the interventions by a researcher. He also tries to understand the reason of drop-out from the study.

Inclusion Criteria:

1. Chronic stroke>6months
2. Age : 20-75 y
3. Able to walk independently over 30 mins (with or without orthosis)
4. Able to use stationary bike

Exclusion Criteria:

1. Physiological condition not stable, cognitive dysfunction, not able to coordinate with examine or treatments.
2. Not able to exercise due to severe cardiopulmonary dysfunction
3. Malnutrition (MNA<11)