The catabolic actions of cortisol resulting in muscle proteolysis occur largely via the ubiquitin–proteasome and lysosomal systems (186, 209–211). Exercise affects receptor expression (205) and relative expression of receptor isoforms; athletes show less GRα mRNA expression in peripheral blood mononuclear cells than do untrained controls, indicating reduced sensitivity (206). Mechanistically, the selective increase in GRβ appears to involve the splicing factor SRp30c (serine/arginine-rich protein p30c) (202, 203). In myoblasts, glucocorticoid exposure results in a dose-dependent decline in GRα expression and a dose-dependent increase in GRβ expression (179). The relative expression of the two alternatively spliced glucocorticoid isoforms and the ratio of GR-α to GR-β expression modulates cellular sensitivity to glucocorticoids (199). Alternative splicing of a single gene results in two major isoforms of glucocorticoid receptor with more than 1,500 variants. Other research suggests that several herbal supplements could also help support healthy testosterone levels, including saw palmetto, ginger, and ashwagandha. In a 2021 study, zinc supplementation increased testosterone levels and improved sexual function in postmenopausal women with low blood levels of zinc. Although the potential benefits of multivitamins are hotly debated, certain supplements may be useful for supporting healthy testosterone levels. Additionally, a 2020 review found that taking a vitamin D supplement increased testosterone levels and improved erectile dysfunction. A healthy balance of protein, fat, and carbs can help optimize your hormone levels and support your overall health. What you eat can affect levels of testosterone as well as other hormones. This is particularly important for individuals aiming to maximize muscle growth while minimizing fat gain. This pathway is crucial for initiating protein synthesis and inhibiting protein breakdown, thereby directly contributing to muscle hypertrophy. One of insulin's most significant contributions to muscle growth is its ability to promote an anabolic environment. This process is essential for sustaining intense physical activity, which is a prerequisite for muscle growth. When insulin is released in response to carbohydrate intake, it facilitates the uptake of glucose into muscle cells, providing a primary energy source for muscle tissue. By understanding and leveraging the natural mechanisms that regulate GH, individuals can optimize their muscle repair processes, whether for athletic performance, injury recovery, or general health. Therefore, lifestyle modifications aimed at promoting GH secretion are essential for maximizing muscle repair and growth potential.
