بررسی سازگاری‌‌‌‌ هورمون‌‌‌‌های تستوسترون و رشد با هشت هفته تمرینات مقاومتی برونگرا با و بدون محدودیت جریان خون

Extended Abstract
Background and Aim: Anabolic hormones such as testosterone and growth hormone play a key role in the physiological adaptations that result from exercise training. These hormones are essential for regulating metabolic processes, increasing muscle mass, and enhancing physical strength. Numerous studies have examined the effects of various training methods on hormonal changes. However, the variations in physiological responses to various types of resistance training, especially extroversion training with and without blood flow restriction, have not yet been clearly defined. Extroversion resistance training, due to the involvement of more muscle fibers, has the potential to create higher stress on the muscular system, which can be a suitable stimulus for the body’s anabolic responses. On the other hand, innovative approaches such as blood flow restriction (BFR) training has also been considered an effective solution in situations where it is not possible to apply high mechanical stress. The present study aimed to investigate the adaptation of testosterone and growth hormone with eight weeks of extroversion resistance training with and without blood flow restriction.
Materials and Methods: This study was a quasi-experimental research with a pre-test-post-test design. The statistical population comprised male club-level soccer players with a history of regular training. Among the volunteers, 40 people were voluntarily selected and then randomly divided into four equal groups: eccentric resistance training with blood flow restriction (n=10), eccentric resistance training without blood flow restriction (n=10), traditional resistance training (n=10), and a control group (n=10). The training program was performed for eight weeks, with three sessions per week. The exercises included selected resistance movements for the upper limbs (such as the chest press) and lower limbs (such as the leg press). The intensity of the exercises for different groups was designed based on the principles of resistance training and in accordance with the objectives of the study. The eccentric resistance training with blood flow restriction group performed the exercises by tying elastic bands in the proximal areas of the limbs to restrict blood flow. In contrast, the eccentric resistance training group without blood flow restriction performed the same training without this restriction. The traditional group also performed traditional resistance training at a higher intensity, and the control group did not receive any intervention. To measure functional changes, the bench press test (for upper body muscle strength) and leg press (for lower body muscle strength) were used in the pre-test and post-test phases. Additionally, hormonal responses were evaluated by collecting blood samples from the brachial vein before and after the intervention, followed by measurement of serum testosterone and growth hormone concentrations using ELISA. Data were analyzed using repeated measure analysis of variance with Bonferroni test, and statistical significance was set at p<0.05.
Findings: Statistical analysis revealed  a significant difference between the studied groups in terms of upper body muscle strength. A repeated measures analysis of variance test showed that after eight weeks of training, the eccentric resistance training group with blood flow restriction and the traditional resistance training group performed significantly better than the control group in the bench press strength test (p<0.001). This finding highlights the high effectiveness of these two types of training on strengthening the upper body muscles of male athletes. In contrast, the eccentric resistance training group without blood flow restriction showed a relative improvement, but this change was not statistically significant. In examining the strength of the lower body muscles through the leg press test, no significant difference was observed between the different groups (p>0.05). This finding could indicate that the designed exercises, especially the eccentric resistance training with blood flow restriction, which were performed at a lower intensity, had a lesser effect on the lower compared to the upper muscles, or that the duration of the training period was not sufficient to create significant changes in this area. Regarding hormonal responses , analysis of the results from blood samples showed that serum testosterone levels did not change significantly after the training period in any of the groups (p=0.27). Similarly, growth hormone levels did not show a significant difference at the end of the training period in the different groups (p=0.88). These results indicate that the resistance training performed, despite creating some desirable functional responses, did not lead to significant stimulation of hormonal axes related to anabolism. Overall, it can be said that traditional resistance training and eccentric training with blood flow restriction were more effective in improving upper body muscle strength than other methods, but these types of interventions did not have a significant effect on changes in lower body muscle strength or hormonal indices over an eight-week period.
Conclusion: The findings of this study indicate that extrinsic resistance training, especially with blood flow restriction, significantly improved upper body muscle strength, while a similar effect was not observed on lower body muscle strength. Additionally, serum levels of testosterone and growth hormones did not change significantly after eight weeks of training in any of the groups. These findings are consistent with some previous studies and may be due to the limited duration of the intervention or the relatively low intensity of the exercises. Despite the absence of hormonal adaptations, the observed functional gains highlight the effectiveness of the intervention, especially eccentric resistance training with blood flow restriction, as a viable strategy for increasing strength when high-intensity exercise is not feasible. Future research should explore longer training durations, higher intensities, and a broader range of physiological markers to better understand the underlying mechanisms and optimize training outcomes.
Ethical Considerations: This study was approved by the Ethics Committee of the Faculty of Medical Sciences, Aliabad Katul Branch of Islamic Azad University (IR.IAU.AK.REC.1396.5).
Compliance with Ethical Guidelines: The present article is extracted from a doctoral dissertation. The present research was conducted in compliance with ethical principles, including obtaining a written consent form to participate in the study, maintaining the confidentiality of the participants’ information, and ensuring their freedom to withdraw from the research process. The research implementation does not involve physical or psychological harm to the participants.
Funding: This research received no financial support from public, private, or nonprofit organizations.
Conflicts of Interest: The authors of this article declare no conflicts of interest.