Background and Objective: Age is the greatest risk factor for cardiovascular disease that is associated with shortens telomere. TRF2 and TERT genes expression in heart tissue   reduce in elderly. These geness are associated with shortens telomere. Exercise can play a useful role in maintaining the length of telomeres. This study was carry out to determine the effect of high intensity interval training (HIIT) and continuous endurance training on TRF2 and TERT gene expression in heart tissue of aged male rats.

Methods: In this experimental study 24 adult aged male rats (88-96 weeks, 363±12 g) allocated into three groups including control, endurance training (5 sessions per week: with 60-70 of maximum speed of group) and HIIT (5 sessions per week: 80 percent in the first and second week, 90% maximum speed of the third week, 100 % until the end of the exercise for 6 weeks). Gene expression of TRF2 and TERT were assessment by Real-time - PCR and the quantification of gene expression levels using the Pfaffl formula.

Results: TRF2 gene significantly increased in HIIT and CET groups in compared to control group (P<0.05). TERT gene non- significantly increased in HIIT and CET groups in compared to the control group.

Conclusion: It seems, 6 weeks of high-intensity interval training and continuous endurance training to be able regulate the growth and longevity of the heart cells by maintaining the length telomere by increasing TRF2 gene expression.