In contrast to previous studies that focused exclusively on testosterone and (sometimes) DHT, when it comes to identifying mechanisms for potential performance increases, the study at hand was designed to investigate the effects of Tribulus terrestris (TT) extracts on muscle mass, muscle damage, and anaerobic performances of trained male boxers and whether those may be brought about by androgen, IGF-1, and/or changes in IGF-1 or the concentration of its binding protein (IGFBP-3). To this ends, the previously mentioned fifteen male boxers were divided into an exercise group (E, n = 7) and an exercise plus TT group (E + TT, n = 8). The two groups both undertook 3-weeks of high intensity and 3-weeks of high volume training. The latter were separated by a 4-week rest period.
The supplement, the aforementioned TT extracts (1,250 mg/day), was orally administered only in the E + TT group, obviously. Before the pills were handed out to the subjects, their exact compositions had been analyzed and their saponin content had been confirmed by UHPLC–Q-TOF/MS.
"All athletes received similar 3-week high intensity training and 3-week high volume training separated by a 4-week rest. Besides special technical training, the main part of the high intensity training was strength training including maximum strength training (twice a week, on Tuesday and Friday) and speed strength training (twice a week, on Monday and Thurs day). For high volume training [see Table 1], the boxers undertook endurance training (10,000 m race every day and low to moderate intensity rope skipping twice a week, on Tuesday and Friday), and special technical training and speed strength training similar to high intensity training" (Ma. 2015).
Table 1: Training protocol of the boxers with high intensity and high volume training (Ma. 2015) | Abbreviations: HR, heart rate; RM, repetition maximum.
Not all TT extracts are created equal! If you've previously taken tribulus supplements and have seen no results, the reason could well be that they did not contain the right amount or type of saponins. As Ma et al highlight, the content of 25(R)-Spirostan-3,6,12-trione/25(R)-Spirostan-4-ene-3,12-dione and TT saponin A varies "depending on geographical region, climate23 and part of herb, which may partly explain the divergent results of TT extracts from different studies" (Ma. 2015).The results of the pre- and post assessments of muscle mass, anaerobic performance, and blood indicators revealed no inter-group differences for testosterone, DHT, muscle mass or total IGF-1. Creatine kinase (CK), the IGF binding protein IGFBP-3 and the subjects' absolute and relative muscle power, on the other hand, increased significantly more in the supplement (E + TT) vs. control (E) group (Figure 1 shows the relative difference of the change from baseline, i.e. ΔE+TT - ΔE).
|Figure 2: Overview of the general role of IGF-1; focus on what is missing when it declines as we age (Berryman. 2013).|
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