The aim of the present study was to determine the effect of 8 weeks of high-intensity interval training with cinnamon supplementation on serum apelin concentration and insulin resistance in obese boys. The current study was of an applied type, in which 42 obese male students of District 4 of Tehran city were randomly selected and equally divided into four groups: 1) exercise, 2) exercise and supplement, 3) supplement, 4) division control. became Blood samples were taken before and after training. Two groups 1 and 2 also performed a high-intensity interval training program for 8 weeks and 2 sessions per week. Also, group 2 (exercise and supplement), in addition to performing the same exercises as group 3 (only supplement), consumed two cinnamon capsules weighing 360 mg daily. Apelin, glucose, and insulin levels were measured with an ELISA kit and the data were analyzed by one-way, two-way analysis of variance and analysis of covariance at a significance level of α≥0.05. The results of the research showed that HIT exercises decreased the serum levels of apelin (P=0.0001), but the supplement and the interaction of exercise and supplement did not have a significant effect on the levels of serum apelin (P>0.05). Also, the results showed that exercise, supplementation, and the interaction of the two have a significant effect on the insulin resistance index (P ≤ 0.05). According to these results, the pivotal role of exercise and cinnamon supplementation in simultaneously improving the pattern of apelin secretion and insulin sensitivity was highlighted.