چكيده لاتين
Introduction: Resistance training and the type of training protocol are one of the most effective methods for increasing muscle strength, muscle growth, and improving hormonal responses in the body. Nowadays, herbal supplements such as Tribulus terrestris have attracted the attention of athletes due to their possible effects on increasing testosterone and improving athletic performance. The aim of the present study was to compare the effect of two resistance training loading methods with and without Tribulus supplementation on the levels of testosterone, cortisol, maximum strength, lipid profile, and body composition of active men.
Methodology: This study was a quasi-experimental study with a pre-test and post-test design with parallel groups. A total of 40 male volunteers (age range 25-35 years), after examining the entry conditions, were non-randomly and homogeneously divided into four groups of 10: the first group received resistance training loading (mean weight 90.97 ± 10.4 and BMI 86.28 ± 6.1), with a constant intensity of 70% of one repetition maximum, the second group received resistance training loading (mean weight 85.6 ± 5.2 and BMI 89.26 ± 81.0) with an intensity of 70% of one repetition maximum along with Tribulus supplementation, the third group received resistance training loading with a pyramidal pattern without supplementation (mean weight 89.72 ± 7.1 and BMI 27.8 ± 5.1), and the fourth group received resistance training loading with a pyramidal pattern along with Tribulus supplementation (mean weight 89.23 ± 9.3 and BMI 27.37 ± 1.99). The training protocol was implemented for 8 weeks (3 sessions per week). The supplement groups consumed 2000 mg of Tribulus extract daily. Dependent variables included testosterone levels, cortisol by ELISA kits, lipid profile by enzymatic-calorimetric method, maximum strength in the chest press, squat, leg extention, leg curl movements by one-repetition maximum test, wrist muscle strength by dynamometer and body fat percentage by body analyzer, measured in two stages before and after the intervention. Data analysis was performed using analysis of covariance test at a significance level of 0.05.
Findings: Resistance training in both patterns significantly improved maximum strength and some blood indices, but maximum strength was observed to increase more in the pyramid training protocol groups and Tribulus supplementation had no effect on strength. The increase in testosterone levels was greater in the supplement groups (P=0.017) and cortisol levels in the pyramid training protocol group with Tribulus supplementation showed the greatest decrease and significant difference (P=0.016). HDL levels increased in all groups (P=0.002) and cholesterol decreased (P=0.001) and these changes were more evident in the supplement groups, but a slight decrease was observed in triglyceride and LDL levels, but it was not significant and significant. Also, resistance training with supplementation caused a slight decrease in body fat percentage, but these changes were also not statistically significant.
Conclusion: Pyramid loading was more effective than traditional training in improving muscle strength, and the main role was played by the intensity and load of training. In contrast, Tribulus supplementation was effective on hormonal responses and lipid profiles, but the improvement in muscle performance was mainly due to the training structure.
