The effect of the eight weeks of high intensity interval training and low intensity continuous training along with Citrus aurantium extract on tumor necrosis factor alpha and interleukin-6 in soleus muscle tissue of aged female rats

immune system in elderly people. This study aimed to investigate the effect of eight weeks of high-intensity interval training (HIIT) and low-intensity continuous training (LICT) along with Citrus aurantium (CA) extract on tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in soleus muscle tissue of aged female rats.  Materials and Methods: A total of 42 aged female rats were divided into (1) control (C), (2) LICT, (3) HIIT, (4) LICT+CA, (5) HIIT+CA, (6) CA, and (7) sham (normal-saline) groups. During eight weeks, HIIT was performed with an intensity of 85-90% of maximum speed and LICT with an intensity of 65% of maximum speed for five sessions per week, and 300 mg/kg/day of Citrus aurantium extract was daily intraperitoneally injected. The collected data were analyzed using one-way analysis of variance with Tukey's post hoc statistical tests (P≤ 0.05). Results: TNF-α in LICT (P=0.001), HIIT+CA (P=0.004) and LICT+CA (P=0.007) groups were significantly lower than the C group. In the LICT group, TNF-α was significantly lower than the CA (P=0.001), HIIT (P=0.001), LICT+CA (P=0.02), and HIIT+CA (P=0.014) groups. It was also lower in the LICT+CA (P=0.007) and HIIT+CA (P=0.011) groups than the HIIT group. IL-6 levels in HIIT+CA group were significantly lower than the control group (P=0.02). Conclusion: It seems that the training (continuous and interval) along with CA extract has favorable effect on TNF-α compared to HIIT; however, investigating the mechanism of intensity and type of training as well as different dosage of CA on IL-6 requires further studies.