Background: Self-myofascial release using a foam roller has short-term effects for improving muscle function and joint range of motion (ROM) and reducing delayed onset muscle soreness (DOMS) after exercise. Objectives: The purpose of our study was to examine the muscle physiological changes for each set in self-myofascial release of the hamstring muscles using a foam roller in order to provide basic data for the most effective program composition for improving muscle tension, stiffness, and flexibility of the hamstring muscles. Design: A quasi-experimental clinical trial. Methods: To confirm the effect of self-myofascial release of the hamstring muscles using a foam roller, muscle tone and stiffness of the hamstring muscles were measured. As an intervention method, the study subject performed four sessions of self-myofascial release by moving a foam roller back and forth on the posterior thigh muscle of the right leg. Results: There were statistically significant changes in the stiffness of the biceps femoris and the flexibility of the hamstring muscles. Conclusion: Self-myofascial release with foam rolling is an effective intervention method for increasing hamstring flexibility and ROM, and it is recommended as effective to perform self-myofascial release for three to four sessions to maintain normal muscle tone and stiffness of the hamstring muscles.

INTRODUCTION
SUBJECTS AND METHODS
    Subjects
    Measurement
    Intervention
    Data analysis
RESULTS
    Change of muscle tone and stiffness on hamstringmuscle
    Change of hamstring muscle flexibility
DISCUSSION
CONCLUSION
ACKNOWLEGEMENT
REFERENCES

• Joongsan Wang(Department of Physical Therapy, Howon University, Gunsan, Republic of Korea)
• Nyeonjun Kim(Department of Physical Therapy, Pohang University, Pohang, Republic of Korea) Corresponding author