Athletic performance in endurance competitions depends on the ability to maintain and produce high energy efficiency per time, and many factors, including exercise and nutrition, play an important role in improving the performance. Therefore, having a good regime and proper use of appropriate supplements have an important role in the performance of athletes [1]. Numerous studies have shown that medicinal plants such as garlic, ginger, fenugreek, pomegranate extract, etc., by preventing platelet aggregation and activating fibrinolytic factors, increase blood fluidity and thus increase blood flow to muscles and increases a person’s ability to perform sports activities [2]. A group of antioxidants that are often good candidates for antioxidant therapy because of their potential role in health are flavonoids. Flavonoids are a group of naturally occurring phenolic compounds commonly found in photosynthetic cells [4]. Thyme is one of the medicinal plants that has many applications in traditional Iranian medicine and is easily accessible due to its wide distribution in most mountainous areas of Iran [5].
Mitochondrial biogenesis is the process by which new mitochondria are formed in a cell. The onset of mitochondrial life is activated by a large number of different signals during cell stimulation or in response to environmental stimuli [6, 7]. One of the major regulators of mitochondrial biogenesis is PGC-1α. It belongs to a relatively large family of nuclear receptors that are associated with a wide range of transcription factors that are involved in a variety of biological responses. It is a potent transcription co-activator. A co-activator is a protein or set of proteins that increases the expression of a gene by binding to an activator or transcription factor that has a region that binds to DNA.

In this study, 40 eight-week-old male white Wistar rats weighing 275-240 g were used prepared from Pasteur Institute of Iran. They were divided into 5 groups of control (n=8), sham (n=8), aerobic exercise (n=8), thyme extract (n=8), aerobic exercise + thyme extract (n=8) by using simple random sampling method (a number was assigned to each rat and then were selected by a lottery method). To prepare thyme extract, the dried thyme powder (400 mg / kg according to LD50) was dissolved in the drinking water of the rats. All rats in all groups got familiar how to run on a treadmill at a speed of 5 m/min and a slope of zero degrees.
Supplementation by thyme extract and aerobic exercise were done for 8 weeks. Aerobic exercise groups practiced 5 sessions per week on a motorized treadmill. Before it, rats trained on the treadmill for 10 minutes a day at a speed of 10 m/min with a slope of 10%. The speed and duration of training gradually increased over the next 2 weeks until the duration and speed of training reached 1 h per day and 27 m/min, respectively [14].
24 hours after the last training session, the rats were dissected and kept at -80 ° C until the start of soleus (SOL) muscle homogenization. Using mortar and liquid nitrogen, the tissues were homogenized and kept in 1.5 ml microtubules with a suitable label [15].
RNA extraction was performed using 50 mg of SOL. A biophotometer (Eppendorf, Germany) with a wavelength of 260 nm was used to measure the quality of extracted RNA. The mean of ODs read was 1.77, which indicates the good quality of the extracted RNA [18].
Transcription to cDNA was performed using a thermo kit according to the manufacturer’s instructions. Prior to the final evaluation of gene expression, the Real Time PCR technique needed to evaluate the efficiency of the reference gene (gapdh) and the target gene (Med), which was done. The efficiency for these two genes was 1 (highest level). The Real Time PCR technique (one step) was done using the SYBR Green master mix (Applied Biosystems) and the relative gene expression level was assessed [16, 17].
For data analysis, first the central tendency and dispersion of PGC-1α in different groups before and after the test were examined. Then, the research hypotheses were examined using one-way analysis of variance at the significant level of p<0.05 (Figure 1). 

The results presented in Table 1 showed no significant difference in the expression level of PGC-1α gene between the study groups before the intervention, but there was a significant difference after intervention (p=0.05), where there was a significant difference between the aerobic exercise + thyme extract group and control and sham groups, but the exercise and supplementation groups were not significantly different from the control and sham groups. 

This study obtained its ethical approval from the University of Tehran (Code: IR.UT.SPORT.REC.1397.015).

This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors. 

All authors equally contributed to preparing this article.

The authors declare no conflict of interest

The authors would like to thank the University of Tehran and Pasteur Institute of Iran for their cooperation.
 

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