Abstarct: Purpose: The purpose of this research was to compare 4 weeks of respiratory muscle training and interval training on improving running time and returning to the initial state of respiratory muscle strength (tail) in healthy non-athletes. Method: This research was experimental and included pre-test and post-test. The statistical sample of this study was composed of healthy non-athletic students of Shahrood University of Technology between the ages of 20 and 40 who were randomly divided into 3 groups of 10 people: endurance interval exercises, breathing exercises, and sham exercises. Before starting the training protocol, a spirometry test was taken from them to measure their breathing capacity, and their pulmonary pressure was measured with a self-made sphygmomanometer. After measuring the pulmonary pressure of the subjects, Bulk test was taken from them until they reached exhaustion. After finishing the treadmill test, pulmonary pressure test was taken from them again at 2, 10, 15 and 30 minutes. Group 1: The endurance interval group did aerobic exercises for 4 weeks. In the first two weeks, intermittent exercises were performed with 40-60% of the reserve heart rate and 3 days a week, and in the last two weeks, the intensity of the exercises was increased to 70% of the maximum reserve heart rate and its days were increased to 4 days a week. Group 2: The group of breathing exercises performed IMT exercises for 4 weeks. In the first two weeks, the subjects performed 30 breaths at a pressure equal to 50% of their maximum MIP for 4 days a week, once a day and 30 breaths each time. In the final two weeks, the subjects resumed IMT training at 60% of the new MIP for 5 days per week and 1 time per day with 30 respiratory efforts. Group 3: The sham group exactly implemented the protocol of the breathing exercises group. The only difference between the sham group and the breathing exercises group was the intensity of the wind work of the Powerbreathe device, which is equivalent to 10-15% of MIP. Statistics: Correlated T-test was used to evaluate intra-group difference, ANCOVA test was used to evaluate inter-group difference, and Bonfferoni post-hoc test was used to identify groups that had differences in ANCOVA test, with a significance level of P=0.05. Findings: The results of intra-group differences regarding running time show that the running time of the interval (P=0.012) and IMT (P=0.006) groups increased significantly, but the running time of the sham group (P=0.406) did not difference significantly compared to the pre-test. Also, the intra-group results of the time frxame of returning to the initial state of inspiratory muscle strength show that the IMT group (P=0.667) from 30 minutes to 10 minutes, the sham group (P=0.099) from 30 minutes to 10 minutes and the interval group (P=0.187) from 30 minutes to 15 minutes, their time frxame has decreased significantly. The difference between groups regarding running time shows that there is a significant difference between the 3 groups (P=0.012). Regarding the return to the initial state of inspiratory muscle strength, the IMT group experienced the fastest return, followed by the sham group and finally the interval training group. Conclusion: According to our research results, it seems Compared to the interval and sham groups, the breathing exercises group has been more effective in improving the running time and returning to the inspiratory state of respiratory muscle strength in healthy non-athletes.