Inclusion Criteria:  Aged 20-75 y/o Healthy people Chronic stroke > 6 months Able to walk independently > 6 minutes with or without orthosis Able to use stationary bike MRS(Modified Rankin Scale) ranged 1 to 3  Exclusion Criteria:  Patients whose heart rate can not be used as the indicator of training intensity (eg, ar-rhythmia, atrial fibrillation, beta-blockers users) With any reason that the patient is not suitable to undergo aerobic training Patients who are unable to do cycling due to musculoskeletal problems Patients who can not follow the instruction of trainers due to cognitive or emotional-problems. Patients whose medical condition is not unstable.