Bom, eu comecei a dar uma pesquisada por interesse proprio na database da faculdade de artigos cientificos sobre a suplementacao de tribulus terrestris e todos os artigos que eu achei afirmam que a suplementacao de tribulus terrestris nao causa nenhum aumento significante no aumento de testosterona, forca, hipertrofia. Nao pesquisei sobre a líbido.
Eles sao em ingles, mas qualquer pessoa com um nivel basicao de ingles consegue entender as partes que estao em negrito.
Edit: reforcando o topico iniciado pelo "craw69"
Elder, P.A.,Hellemans, J., Lewis, J.G.,Dawson, T., (2001) New Zealand Journal of Sports Medicine Summer, 29 (4). p. 74-77.
Tribulus Terrestris increases Luteinising Hormone release and subsequently raises testosterone. This claim is the basis for the widespread use of Tribulus Terrestris as a bodybuilding and anabolic agent and increases of between 50-300 % for testosterone levels have been made. If this claim is true then the level of testosterone and its metabolites should be increased markedly in plasma and urine after ingestion. Six healthy men ingested 1 gram of Tribulus Terrestris per day for four weeks and blood and urine levels were taken at the end of two and four weeks. These levels were compared with baseline levels for a number of hormones and metabolites. The analysis showed no overall increase from baseline of any hormones for any individual or when as percentage of the basal level for all individuals. All results fall within a normal biological day to day variation. Thus advertising claims that Tribulus Terrestris causes testosterone to rise markedly in males leading to increased libido, sperm production, weight and muscle growth have not been substantiated in this study. The overall hormone increase is insignificant and this study would suggest that Tribulus Terrestris does not alter Luteinising Hormone levels nor testosterone outside any biological day to day variation.
Rogerson S, Riches C.J., Jennings C., Weatherby R.P., Meir R.A., Marshall-Gradisnik S.M. (2007) The effect of five weeks of Tribulus terrestris supplementation on muscle strength and body composition during preseason training in elite rugby league players . J Strength Cond Res. 21(2):348-53.
Tribulus terrestris is an herbal nutritional supplement that is promoted to produce large gains in strength and lean muscle mass in 5-28 days (15, 18). Although some manufacturers claim T. terrestris will not lead to a positive drug test, others have suggested that T. terrestris may increase the urinary testosterone/epitestosterone (T/E) ratio, which may place athletes at risk of a positive drug test. The purpose of the study was to determine the effect of T. terrestris on strength, fat free mass, and the urinary T/E ratio during 5 weeks of preseason training in elite rugby league players. Twenty-two Australian elite male rugby league players (mean +/- SD; age = 19.8 +/- 2.9 years; weight = 88.0 +/- 9.5 kg) were match-paired and randomly assigned in a double-blind manner to either a T. terrestris (n = 11) or placebo (n = 11) group. All subjects performed structured heavy resistance training as part of the club's preseason preparations. A T. terrestris extract (450 mg.d(-1)) or placebo capsules were consumed once daily for 5 weeks. Muscular strength, body composition, and the urinary T/E ratio were monitored prior to and after supplementation. After 5 weeks of training, strength and fat free mass increased significantly without any between-group differences. No between-group differences were noted in the urinary T/E ratio. It was concluded that T. terrestris did not produce the large gains in strength or lean muscle mass that many manufacturers claim can be experienced within 5-28 days. Furthermore, T. terrestris did not alter the urinary T/E ratio and would not place an athlete at risk of testing positive based on the World Anti-Doping Agency's urinary T/E ratio limit of 4:1.
Brown G.A., Vukovich M.D., Reifenrath T.A., Uhl N.L., Parsons K.A., Sharp R.L., King D.S. (2000). Effects of anabolic precursors on serum testosterone concentrations and adaptations to resistance training in young men . Int J Sport Nutr Exerc Metab. 10(3):340-59.
The effects of androgen precursors, combined with herbal extracts designed to enhance testosterone formation and reduce conversion of androgens to estrogens was studied in young men. Subjects performed 3 days of resistance training per week for 8 weeks. Each day during Weeks 1, 2, 4, 5, 7, and 8, subjects consumed either placebo (PL; n = 10) or a supplement (ANDRO-6; n = 10), which contained daily doses of 300 mg androstenedione, 150 mg DHEA, 750 mg Tribulus terrestris, 625 mg Chrysin, 300 mg Indole-3-carbinol, and 540 mg Saw palmetto. Serum androstenedione concentrations were higher in ANDRO-6 after 2, 5, and 8 weeks (p <.05), while serum concentrations of free and total testosterone were unchanged in both groups. Serum estradiol was elevated at Weeks 2, 5, and 8 in ANDRO-6 (p <.05), and serum estrone was elevated at Weeks 5 and 8 (p <.05). Muscle strength increased (p <.05) similarly from Weeks 0 to 4, and again from Weeks 4 to 8 in both treatment groups. The acute effect of one third of the daily dose of ANDRO-6 and PL was studied in 10 men (23 +/- 4 years). Serum androstenedione concentrations were elevated (p <.05) in ANDRO-6 from 150 to 360 min after ingestion, while serum free or total testosterone concentrations were unchanged. These data provide evidence that the addition of these herbal extracts to androstenedione does not result in increased serum testosterone concentrations, reduce the estrogenic effect of androstenedione, and does not augment the adaptations to resistance training.
Antonio, J.,Uelmen, J.,Rodriguez, R.,Earnest, C. (2000) The effects of tribulus terrestris on body composition and exercise performance in resistance-trained males. / Effets de la Tribulus terrestris sur la composition de la masse corporelle et les performances physiques chez des hommes pratiquant la musculation. International Journal of Sport Nutrition & Exercise Metabolism June 10 (2). p. 208-215
The purpose of this study was to determine the effects of the herbal preparation Tribulus terrestris (tribulus) on body composition and exercise performance in resistance-trained males. Fifteen subjects were randomly assigned to a placebo or tribulus (3.21 mg per kg body weight daily) group. Body weight, body composition, maximal strength, dietary intake, and mood states were determined before and after an 8-week exercise (periodized resistance training) and supplementation period. There were no changes in body weight, percentage fat, total body water, dietary intake, or mood states in either group. Muscle endurance (determined by the maximal number of repetitions at 100-200 % of body weight) increased for the bench and leg press exercises in the placebo group (p < .05; bench press +/- 28.4 % , leg press +/- 28.6 % ), while the tribulus group experienced an increase in leg press strength only (bench press +/- 3.1 % , not significant; leg press +/- 28.6 % , p < .05). Supplementation with tribulus does not enhance body composition or exercise performance in resistance-trained males.
Saudan, C., Baume, N., Emery, C., Strahm, E.(2008).Saugy, MartialShort term impact of Tribulus terrestris intake on doping control analysis of endogenous steroids
Forensic Science International, 178 (1) pe7-e10
Tribulus terrestris is a nutritional supplement highly debated regarding its physiological and actual effects on the organism. The main claimed effect is an increase of testosterone anabolic and androgenic action through the activation of endogenous testosterone production. Even if this biological pathway is not entirely proven, T. terrestris is regularly used by athletes. Recently, the analysis of two female urine samples by GC/C/IRMS (gas chromatography/combustion/isotope-ratio-mass-spectrometry) conclusively revealed the administration of exogenous testosterone or its precursors, even if the testosterone glucuronide/epitestosterone glucuronide (T/E) ratio and steroid marker concentrations were below the cut-off values defined by World Anti-Doping Agency (WADA). To argue against this adverse analytical finding, the athletes recognized having used T. terrestris in their diet. In order to test this hypothesis, two female volunteers ingested 500mg of T.terrestris, three times a day and for two consecutive days. All spot urines were collected during 48h after the first intake. The 13C/12C ratio of ketosteroids was determined by GC/C/IRMS, the T/E ratio and DHEA concentrations were measured by GC/MS and LH concentrations by radioimmunoassay. None of these parameters revealed a significant variation or increased above the WADA cut-off limits. Hence, the short-term treatment with T. terrestris showed no impact on the endogenous testosterone metabolism of the two subjects.
Este post foi editado por pietrofp: 12:21:02 em 12/12/2012