Background: Physical therapy applied to stroke patients is recognized as a treatment that promotes function recovery, and it is a widely known fact that constant exercise should be performed. However, there are insufficient studies on exercise intensity and exercise time that can minimize side effects and maximize function recovery for exercise therapy. Objectives: To determine the effect of exercise variables on CPK generation during aerobic exercise in stroke patients and to discover how to use appropriate exercise intensity and time when conducting an exercise for function recovery in stroke patients. Design: Quasi-experimental research. Methods: This study classified subjects into three groups (low-intensity exercise group: LIE, moderate-intensity exercise group: MIE and high-intensity exercise group: HIE) according to exercise intensity, and was further classified into two groups (10-minute exercise group: 10MG and 20-minute exercise group: 20MG) according to exercise time variables within each exercise intensity group. After, the change in CPK according to exercise intensity and time was confirmed through hematological analysis. Results: In LIE and MIE, the CPK blood concentrations before and after exercise were increased in 10MG and 20MG, which was not statistically significant (P>.05). In HIE, the CPK blood concentrations before and after exercise were increased in 10MG, and it was statistically significant (P<.05). In HIE, the CPK blood concentrations before and after exercise were increased in 20MG, and it was statistically significant (P<.01). In 10MG and 20MG, the CPK blood concentrations before and after exercises were increased in all intensity group, and there was a statistically significant difference only in HIE. Conclusion: From the results of this study, considering CPK, it will be helpful to recover and improve function if the exercise intensity setting is applied in the type of moderate intensity exercise during physical therapy interventions in stroke patients.