Background: The circuit exercise program is a continuous method that combines complex training types and is an exercise method that is performed to improve performance by improving basic physical strength such as strength, agility, endurance and muscular endurance. Objectives: To examine the effect of exercise program on pulmonary function of professional volleyball players. Design: Randomized controlled trial. Methods: 22 professional volleyball players were divided into two groups of 11 each. A high intensity interval exercise program and circuit exercise program were performed twice a week for 45 minutes for 4 weeks. Results: The changes in pulmonary function in professional volleyball players were significantly different pre and post the intervention in both groups and the interval exercise program group showed a more significant difference before and after the intervention in Forced Expiratory Volume in 1 Second (FEV1) and Forced Expiratory Volume in 1 Second/Forced Vital Capacity (FEV1/FVC) (P<.05). In addition, there was also a significant difference in FEV1 and FEV1/FVC between two groups (P<.05). Conclusion: The interval exercise program group was effective in improving pulmonary function for professional volleyball players.

INTRODUCTION
SUBJECTS AND METHODS
    Subjects
    Outcome Measures
    Interventions
    Experimental Procedures
    Data and Statistical Analysis
RESULTS
DISCUSSION
CONCLUSION
ACKNOWLEDGMENT
REFERENCES

• Yongyoun Kim(Department of Physical Therapy, Dongnam Health University, Suwon, Republic of Korea)
• Ayeon Kim(Rehabilitation Center, Hospital Chung, Seongnam, Republic of Korea) Corresponding author