Effects of resistance, endurance and combined training on interleukin-6 gene expression in fast-twitch muscle tissue of male wistar rats

Subject Areas : Cellular & Molecular Exercise Biology and Sports Genetic

Ali Akbar Ajgholi ¹ , tahereh bagherpour ^{2 *} , Nematolah Nemati ³

1 - Department of Sport Sciences, Da. C., Islamic Azad University, Damghan, Semnan, Iran.
2 - Department of Sports Sciences, Da. C., Islamic Azad University, Damghan, Semnan, Iran
3 - Department of Sport Sciences, Da. C., Islamic Azad University, Damghan, Semnan, Iran.

Received: 2025-04-14 Accepted : 2025-07-01 Published : 2025-09-09

Keywords: Inflammation, interleukin-6, fast twitch fibers, exercise training,

Abstract :

The effects of resistance and endurance training alone and separately have been investigated in numerous studies on inflammatory markers such as interleukin-6, and contradictory results have been reported. The combination of resistance and endurance training can have additive effects that require further research. Given the lack of knowledge about the effects of combined resistance and endurance training on the expression of the inflammatory marker interleukin-6 gene in muscle tissue, and especially the fact that no study has been conducted to determine and compare changes in interleukin-6 gene expression in the extensor digitorum longus muscle tissue (fast-twitch fiber), the present study aims to study the effects of different types of training on the fast-twitch fiber. The present experimental study aimed to determine and compare the effects of eight weeks of resistance, endurance, and combined training on interleukin-6 gene expression in the extensor digitorum longus muscle tissue of two-month-old male Wistar rats using an animal model in a multi-group research design with a control group. Resistance training was performed for 8 weeks and 5 sessions per week in 3 sessions with 6 repetitions in each session. Rest intervals between sessions were 3 minutes and rest intervals between repetitions in each session were 45 seconds. Resistance was applied by tying weights to the tails of the rats’ equivalent to different percentages of body weight on a constant 15 percent incline during the training period. The endurance training group participated in the endurance training program for 8 weeks. The treadmill incline was 15 percent throughout the training period. The treadmill speed also started at 20 meters per minute in the first week and reached 30 meters per minute in the last week. The duration of the exercise started from 10 minutes per day in the first week and increased to 50 minutes per day in the last week. Real Time-PCR method was used to examine the level of mRNA expression. The mean of the variables in the groups (except the control group) were compared using one-way ANOVA and Bonferroni tests to determine the differences between the groups. The mean of variables among each group and the control were compared using one-sample t-test to determine the differences within the groups. The results show a change and decrease in the relative expression of the interleukin-6 gene in the extensor digitorum longus muscle of rats due to eight weeks of resistance, endurance, and combined training. A comparison between the two resistance and endurance training groups showed that there was no difference between these two training methods in decrease of interleukin-6 gene expression. Given the optimal and more desirable effects of combined training on body weight and the interleukin-6 gene expression; it is recommended that, if necessary and appropriate conditions exist and there are no restrictions, combined training be used instead of performing resistance or endurance training separately.

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