Testosterone is significantly correlated with aggression and competitive behaviour and is directly facilitated by the latter. There are two theories on the role of testosterone in aggression and competition.[77] The first one is the challenge hypothesis which states that testosterone would increase during puberty thus facilitating reproductive and competitive behaviour which would include aggression.[77] Thus it is the challenge of competition among males of the species that facilitates aggression and violence.[77] Studies conducted have found direct correlation between testosterone and dominance especially among the most violent criminals in prison who had the highest testosterone levels.[77] The same research also found fathers (those outside competitive environments) had the lowest testosterone levels compared to other males.[77]

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There are a lot of test booster blends out there. A lot of them are junk. I have tried to cover the most effective herbs above. As always, I recommend doing your own research and experiment to see if you notice an effect. If you would like one easy herbal solution I recommend starting with Mike Mahlers Aggressive Strength product purely because I have solid anecdotal evidence of its effectiveness. But again, supplements should be seen purely as that - a supplement to a healthy diet, plenty of sleep, hard training with adequate rest.
As already indicated previously, testosterone levels, particularly bioavailable testosterone, fall with advancing age. This decline in testosterone availability may start to occur early in the forth decade but it usually becomes clinically manifest in the 50s and 60s. Although there is continuing debate about the best way to diagnose hypogonadism in the aging male, there appears to be a general consensus that symptomatic men with reduced levels of testosterone should be given a trial of testosterone therapy if there is no contraindication to do so (Bain et al 2007).
We start with plastic. A lot of plastic contains bisphenol A (BPA); BPA is a weak synthetic estrogen. Like many other chemicals used in making plastics, BPA is a hormone disruptor and can block or mimic hormones and how they act in the body (34). If you think you’re safe with BPA plastic, think again. Research shows that BPA free plastic has similar estrogen-like effects on the body.
Two of the immediate metabolites of testosterone, 5α-DHT and estradiol, are biologically important and can be formed both in the liver and in extrahepatic tissues.[151] Approximately 5 to 7% of testosterone is converted by 5α-reductase into 5α-DHT, with circulating levels of 5α-DHT about 10% of those of testosterone, and approximately 0.3% of testosterone is converted into estradiol by aromatase.[2][151][157][158] 5α-Reductase is highly expressed in the male reproductive organs (including the prostate gland, seminal vesicles, and epididymides),[159] skin, hair follicles, and brain[160] and aromatase is highly expressed in adipose tissue, bone, and the brain.[161][162] As much as 90% of testosterone is converted into 5α-DHT in so-called androgenic tissues with high 5α-reductase expression,[152] and due to the several-fold greater potency of 5α-DHT as an AR agonist relative to testosterone,[163] it has been estimated that the effects of testosterone are potentiated 2- to 3-fold in such tissues.[164]

A large number of trials have demonstrated a positive effect of testosterone treatment on bone mineral density (Katznelson et al 1996; Behre et al 1997; Leifke et al 1998; Snyder et al 2000; Zacharin et al 2003; Wang, Cunningham et al 2004; Aminorroaya et al 2005; Benito et al 2005) and bone architecture (Benito et al 2005). These effects are often more impressive in longer trials, which have shown that adequate replacement will lead to near normal bone density but that the full effects may take two years or more (Snyder et al 2000; Wang, Cunningham et al 2004; Aminorroaya et al 2005). Three randomized placebo-controlled trials of testosterone treatment in aging males have been conducted (Snyder et al 1999; Kenny et al 2001; Amory et al 2004). One of these studies concerned men with a mean age of 71 years with two serum testosterone levels less than 12.1nmol/l. After 36 months of intramuscular testosterone treatment or placebo, there were significant increases in vertebral and hip bone mineral density. In this study, there was also a significant decrease in the bone resorption marker urinary deoxypyridinoline with testosterone treatment (Amory et al 2004). The second study contained men with low bioavailable testosterone levels and an average age of 76 years. Testosterone treatment in the form of transdermal patches was given for 1 year. During this trial there was a significant preservation of hip bone mineral density with testosterone treatment but testosterone had no effect on bone mineral density at other sites including the vertebrae. There were no significant alterations in bone turnover markers during testosterone treatment (Kenny et al 2001). The remaining study contained men of average age 73 years. Men were eligible for the study if their serum total testosterone levels were less than 16.5 nmol/L, meaning that the study contained men who would usually be considered eugonadal. The beneficial effects of testosterone on bone density were confined to the men who had lower serum testosterone levels at baseline and were seen only in the vertebrae. There were no significant changes in bone turnover markers. Testosterone in the trial was given via scrotal patches for a 36 month duration (Snyder et al 1999). A recent meta-analysis of the effects on bone density of testosterone treatment in men included data from these studies and two other randomized controlled trials. The findings were that testosterone produces a significant increase of 2.7% in the bone mineral density at the lumber spine but no overall change at the hip (Isidori et al 2005). These results from randomized controlled trials in aging men show much smaller benefits of testosterone treatment on bone density than have been seen in other trials. This could be due to the trials including patients who are not hypogonadal and being too short to allow for the maximal effects of testosterone. The meta-analysis also assessed the data concerning changes of bone formation and resorption markers during testosterone treatment. There was a significant decrease in bone resorption markers but no change in markers of bone formation suggesting that reduction of bone resorption may be the primary mode of action of testosterone in improving bone density (Isidori et al 2005).
This is because your body is really good at self-regulating your hormone levels. So if you have normal testosterone levels, boosting above your natural base level may at best give you a few hours while your body makes, and then immediately processes out, the excess testosterone. This means you might experience higher than your average testosterone levels, but not by much, and only for a little while.

In males, testosterone is synthesized primarily in Leydig cells. The number of Leydig cells in turn is regulated by luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In addition, the amount of testosterone produced by existing Leydig cells is under the control of LH, which regulates the expression of 17β-hydroxysteroid dehydrogenase.[128]

Another recent development is the production of adhesive tablets which are applied twice daily to the buccal mucosa on the gum above the incisor teeth. The tablets gradually release testosterone into the systemic venous circulation and steady state physiological concentrations are achieved in most patients within two days (Ross et al 2004). Some patients do not like the feeling of the tablet in the mouth or find that there is an abnormal taste in the mouth, but local adverse effects are usually mild and transient (Wang, Swerdloff et al 2004).
Such sort of injuries varies in severity and extent of damage markedly from one person to the other and withdrawal of the drug/supplement coupled with proper medical attention suffice in terms of alleviating the symptoms.[8,12] This was observed in the present case. However, the liver injury observed here may not be confidently linked to product consumption as the subject later reported that the following recovery he consumed two more courses of the booster with no side effects. Tests performed following hospital discharge, and repeated use of the product showed AST and ALT to be slightly high, whereas the rest of the blood parameters tested appeared to be normal. The AST/ALT ratio is considered to be a very important parameter for the evaluation of liver diseases, such as non-alcoholic fatty liver disease,[13] though it is rarely considered alone. Overall, the evidence was inconclusive in the present work in terms of linking the use of a testosterone booster with liver injury. However, even though a single case report cannot establish causality with statistical power.[13] Further research on the usage of a commercial testosterone booster within large populations for a long period is necessary to investigate whether the symptoms shown in the present case were significantly present in other athletes consuming the same commercial product or not. To guarantee an optimal outcome with no severe side effects, further research is warranted to confirm the present findings and determine whether the effects observed in this case report would be statistically significant in larger samples.
Total levels of testosterone in the body are 264 to 916 ng/dL in men age 19 to 39 years,[165] while mean testosterone levels in adult men have been reported as 630 ng/dL.[166] Levels of testosterone in men decline with age.[165] In women, mean levels of total testosterone have been reported to be 32.6 ng/dL.[167][168] In women with hyperandrogenism, mean levels of total testosterone have been reported to be 62.1 ng/dL.[167][168]
Hypogonadism is a disease in which the body is unable to produce normal amounts of testosterone due to a problem with the testicles or with the pituitary gland that controls the testicles. Testosterone replacement therapy can improve the signs and symptoms of low testosterone in these men. Doctors may prescribe testosterone as injections, pellets, patches or gels.