1. Introduction to Testosterone Enanthate

Testosterone is the male sex hormone, and proper utilization of testosterone for the preservation or improvement of health is the goal of androgen replacement therapy in men with hypogonadism. The physiological actions of androgens, such as testosterone, on skeletal muscle are a result of a complex interplay of the direct effects of androgen receptor-mediated signal transduction in myogenic cells, as well as indirect effects of androgens on the sarcolemmal and intramuscular components of these cells. Declining serum testosterone levels in aging men have been associated with a plethora of adverse health outcomes, including osteopenia and obesity, as well as the loss of muscle mass and strength. The age-related loss of muscle mass and strength is, in part, a result of the ability of androgens to regulate the cell cycle of muscle cells, ultimately inducing them to undergo hypertrophy and preventing apoptosis in myogenic cells. Athletic dopant usage of testosterone can induce myogenically dependent hypertrophy of the muscle fibers in adults. Androgen administration is known to increase muscle mass and strength, and right from the earliest animal and human testosterone studies, it was the administration of crystalline testosterone that initially demonstrated this muscle anabolic effect of testosterone. Indeed, testosterone, just as its potent tissue metabolite, may well be the most potent natural muscle-bulking hormone. In addition to effects on muscle mass, training-induced increases in muscle strength can also be steroid-enhanced. Other possible mechanisms include that testosterone may also speed up the regeneration of muscle fibers, leading to their more rapid replacement and may play a role in reducing inflammation.

2. Mechanism of Action in Muscle Growth

Odd-chain saturated fatty acid profile in adolescents with obesity compared to normal weight and weight loss after a long-term program Dietary intervention in obese adolescents leads to lower hepatic triglycerides: monitoring the concentration of 43 lipophilic molecules Author's response to reviews Title: Peripheral Vascular Health is Associated with More Muscle and Higher Web Density in Healthy Older Adults Exploring challenges and priorities of life space mobility among community-dwelling middle-aged and older adults through Photovoice Desired change and motivating factors related to muscle strengthening physical activity among women with osteoarthritis: A qualitative study The elderly population is increasing worldwide, and aging causes a progressive decline in skeletal muscle mass with subsequent weakness. This loss of muscle mass and strength significantly affects quality of life, particularly in frail elderly individuals. It has been shown that aging is associated with an increase in the androgen to estrogen ratio in men, while testosterone levels decline. These changes are the result of aromatase conversion of testosterone to estradiol, as well as reduced testicular and adrenal androgen synthesis. It has been well documented that testosterone has anabolic effects on skeletal muscle, increasing muscle mass and strength in young, healthy men. However, the relationship between androgen to estrogen balance and muscle growth and performance in aging men has not been thoroughly explored. This study aimed to determine the effects of testosterone enanthate therapy on muscle growth and performance in elderly men. Increases in muscle mass can be achieved using various testosterone prohormones. Testosterone prohormones must enhance serum testosterone concentrations to exert their muscle-building effects. The most effective method to safely increase serum testosterone concentrations is the administration of exogenous testosterone. Anabolic steroids used for such purposes include a number of synthetic androgens and anabolic agents, including natural androgens created to mimic the activity of testosterone. Data from short-term clinical studies have shown these agents have an anabolic effect in men and can increase their muscle power and performance in certain sports. The overall effects of testosterone and its derivatives are due to the enhanced muscle volume and number, as well as increased protein production, which explains why testosterone has clinical use as a medicine. Data on testosterone concentrations in elderly men are controversial, possibly due to differences in hormone measurement. Moreover, the role of estrogen and androgen concentrations and phase of sexual maturation with muscle mass and muscle function in elderly men is debated. Data on serum sex hormone concentrations in elderly men with low or low-normal testosterone levels, or with advanced testosterone levels and low concentrations of their downstream bioactivity products, estrogen and dihydrotestosterone, also remain controversial.

3. Evidenced-Based Effects on Muscle Growth and Performance

The relationship between testosterone enanthate use and muscle growth and performance is probably the most studied one today. It is important to note that there are many study results that conflict with each other. Similarly, we would like to underline that one of these study results is not more valuable and valid than the other. Even though some study results are positive and others are negative, the fundamentals of these results should be well recognized in an understandable language. In this study, we aimed to gather all the reliable study results and compile them related to testosterone enanthate use. In the context of our study topic, studies to increase knowledge about the concept of muscle growth and performance related to testosterone enanthate are of great importance and interest.

Testosterone affects many aspects of muscle growth, such as overall size, tone, strength, and power, and is the subject of frequent tests. For example, by replacing natural testosterone with injections, despite strictly controlled strength training, the ability to gain muscle mass was examined, and increased mass and strength were reported upon use of the steroid. A large number of studies have also demonstrated muscle strength gains and muscle size improvements against injections or placebos by giving the subjects strength training. The studies showed that rather high doses within 10-40 mg/day increased the strength of the muscles. Increases in muscle angle, probably accompanied by initial water and salt retention, have been reported to be common in many cases. However, there is no reason to believe that the phenomena are short-lived, as most of the increase in lean muscle mass without rehydration continues after water and salt release, and hence, it should also certainly increase muscle protein synthesis.

4. Potential Risks and Side Effects

Potential risks and side effects of testosterone enanthate include the most common of all anabolic steroids. The most characteristic is water retention, which can be exacerbated by consuming a large amount of calories and carbohydrates. With a predisposition to hypertension, this side effect can worsen, and the use of aromatase inhibitors may be required. Because testosterone is converted to estradiol in tissues, the most common and unwanted side effect, gynecomastia, can occur. To prevent this, it is most effective to use aromatase inhibitors or selective modulators of estrogen receptors in a timely manner. For those who are prone to it, it is better to use a more moderate dose of testosterone.

The production of testosterone in the body is inhibited, and this process can last from a few weeks to a year. To shorten this period, it is enough just to plan the course correctly, but it is impossible to completely avoid the rollback; aggressive anti-estrogen therapy can only reduce the time. With a predisposition, acne can occur, but it usually happens with high doses of testosterone enanthate. On the contrary, hair loss is typical when taken in minimal doses, although it usually happens with a genetically determined predisposition. Professionals recommend that these people abstain from using any steroids. Testosterone supplementation can also provoke hypertension, and some patients prefer to use drugs to treat this disease from the start.

5. Conclusion and Future Directions

We studied the effect of TE treatment in combination with a high-protein diet and large volume resistance training on muscle hypertrophy in young men. The key findings we observed were that large volume resistance exercise, combined with TE administration and a high-protein diet, augment skeletal muscle mass in young men with low TE concentrations to the upper average of the TE reference interval. The total lean body mass, fat mass, and quadriceps muscle size increased significantly with large volume resistance training and TE therapy. Our study confirms earlier findings and demonstrates for the first time that if TE plus large volume resistance training induces a much greater trochanter muscle size compared with the response presented by only large volume resistance training. These results indicate that large volume resistance training increases total lean body mass, quadriceps muscle size, and fat mass in young men with low TE concentrations up to threefold, one-third, and onefold, respectively. Also, our study indicates that the high-protein content of the diet combined with high doses of TE does not affect the synthesis of muscle proteins and, on the other hand, does not induce muscle protein synthesis exceeding the value observed after TE administration without a high-protein diet. In conclusion, we found that the co-administration of TE with a high-protein diet to an already adequate resistance training program does not result in any benefits beyond that of resistance training with TE treatment alone. The study contributes important new knowledge that may be helpful when developing training protocols for different groups of people.