اثر تمرین هوازی فزآینده بر سطح سرمی بتا آمینو ایزوبوتیریک اسید، شاخص مقاومت به انسولین و درصد چربی بدن در زنان جوان چاق

Extended Abstract
Background and Aim: Obesity has emerged as one of the most critical health issues affecting humans in recent years. Adipose tissue (AT) is categorized into white adipose tissue (WAT), which represents 95% of AT mass, brown adipose tissue (BAT), which comprises less than 2% in adults, and beige adipose tissue, which is difficult to quantify. The findings show that BAT levels are significantly lower in obese individuals and that there is a negative relationship between BAT and body mass index (BMI) and fat percentage. One of the important factors in the conversion of WAT to BAT is beta-aminoisobutyric acid (BAIBA), which has been identified as a small exercise-mediated myokine. Overall, the mechanisms associated with BAIBA often include inhibition of adipogenesis, enhancement of lipolysis, stimulation of BAT/beige development, and improvement of glucose metabolis. Insulin resistance, as one of the complications of obesity and overweight, is caused by a decrease in the response of cell membrane receptors to insulin in the blood, leading to increased blood sugar and increased concentration of free fatty acids. Given these associations, the present study aimed to investigate the effect of eight weeks of incremental aerobic activity on serum BAIBA levels, plasma insulin resistance index, and body fat percentage in young obese women.
Materials and Methods: The statistical population of the present study consisted of obese women with BMI ≥30 kg/m2 and an age range of 30 to 35 years. Inclusion criteria were: being in overall good health; having no known medical conditions; not taking any medications, supplements, or specific drugs; and not having participated in any structured exercise program during the past six months. Based on these criteria, 20 eligible participants were recruited and randomly assigned to either an exercise or a control group (n=10 per group). The incremental aerobic exercise program was implemented for eight weeks (24 sessions, three sessions per week). Each exercise session included 10 minutes of warm-up (walking, light jogging, stretching, and mobility exercises) and 10 minutes of cool-down (slow jogging, walking, and stretching exercises). The duration of the activity was 30 to 55 minutes and the intensity of the activity was 55 to 65% of the maximum heart rate reserve (HR reserve). 24 hours before the start of the training program and 48 hours after the last training session, blood sampling was performed from the brachial vein of the subjects. The obtained serum was stored in a freezer at -20 °C for subsequent measurements. The serum BAIBA and insulin concentration level were measured using an ELISA kit for human samples. Serum glucose concentration was measured using an enzymatic calorimetric method, and to assess insulin resistance, the evaluation model method insulin resistance index (HOMA-IR) was used according to the formula (fasting blood glucose × fasting insulin):22.5. After collecting data and entering the information into SPSS version 26 statistical software, the raw data were analyzed. Considering the natural distribution of the data and the homogeneity of variances, the analysis of covariance test was used to compare the means of the groups in the pre-test and post-test stages and for inter-group comparisons, a significance level of p≤0.05 was used throughout the analysis.
Results: The results revealed a significant increase in serum BAIBA levels in the training group after the intervention compared to the pre-test and in comparison to the control group (p=0.001). Additionally, the HOMA-IR and body fat percentage showed a significant decrease in the training group following the intervention, with these reductions also being statistically significant when compared to the control group (p=0.001) (Table 1).
Conclusion: BAIBA is a key regulator of glucose and lipid metabolism. Plasma BAIBA levels are inversely associated with metabolic risk variables and increase with exercise. As a unique myokine, BAIBA reduces insulin resistance and inflammation in skeletal muscle, promotes browning of white adipose tissue, induces fatty acid oxidation through the AMPK-PPARδ (AMP-activated protein kinase- peroxisome proliferator-activated receptor δ) pathway in skeletal muscle, and thereby regulates energy expenditure. Begriche et al. (2008) showed that BAIBA reduced body fat percentage as well as lipogenesis in mice and Tanianskii et al. (2019) stated that BAIBA acts in conditions of free fatty acid overload, such as physical activity and diabetes. Consistent with the present findings, Galdavi et al. (2022) showed that eight weeks of continuous light to moderate intensity exercise, as one of the appropriate treatment strategies, can be effective in reducing disorders related to overweight and obesity by increasing insulin sensitivity and reducing body fat percentage. Because of BAIBA, insulin resistance and body fat improvement it can be considered of progressive aerobic training as an effective strategy in reducing disorders related to overweight and obesity.
Compliance with ethical guideline: In accordance with ethical research standards, the present study was conducted with full respect for the dignity and rights of participants, while ensuring strict confidentiality of medical information. The ethical principles outlined in the Declaration of Helsinki were adhered to throughout the research process. Additionally, all participants were fully informed about the nature and objectives of the study, and their voluntary participation was secured through the provision of written informed consent.
Funding: This research is based on a master’s thesis from a student at the Islamic Azad University, Bojnourd Branch, and was conducted without any financial support..
Conflicts of interest: There are no conflicts of interest regarding this article.