These studies highlight the importance of estrogen in determining the sensitivity of muscle to anabolic signaling; however, more research is needed to understand whether monthly variations in estrogen have the same effect on anabolic signaling seen with chronic loss of estrogen. For example, 24 weeks of estrogen deficiency resulted in a 10% decrease in strength that corresponded with an 18% decrease in CSA (Kitajima and Ono, 2016). Within these tissues, estrogen is known to regulate metabolism (Nelson and Bulun, 2001), however, it is still unclear whether these effects are beneficial or harmful. These pills typically maintain estradiol levels at ~25 pg/ml and decrease the ovulatory rise in estrogen (Mishell et al., 1972). Beyond the nucleus, estrogen has a variety of post-transcriptional effects such as regulating the redox state of the cell (Kumar et al., 2010), altering mitochondrial function (Yao and Brinton, 2012), and directly inhibiting the activity of specific enzymes (Lee C. A. et al., 2015). In fact, these authors found that knee laxity increased between 1 and 5 mm between the first day of menstruation and the day following ovulation, depending on estrogen levels. In men and women with no history of knee injury, the men showed no statistical difference in knee laxity over time; however, in women laxity increased from 4.7 ± 0.8 mm in the follicular phase, to 5.3 ± 0.7 mm in the ovulatory phase (Deie et al., 2002). Interestingly, women suffer fewer muscle injuries, and more ligament ruptures than men (Arendt and Dick, 1995; Sewright et al., 2008; Hägglund et al., 2009; Edouard et al., 2016; Leblanc et al., 2017). Since eccentric movements produce more muscle injury than concentric or isometric movements (Clarkson and Monica, 2002; LaStayo et al., 2003; Brockett et al., 2004), this means that muscles attached to stiff tendons will suffer more injury for a given movement than those attached to compliant tendons. In terms of performance, a stiff tendon transmits the force produced by a muscle to the bone faster and this can improve performance. Due to its role in connecting a compliant muscle to a stiff bone, a stiffer tendon is not always beneficial. Within the musculoskeletal system, tendons, and ligaments (we will refer to these tissues collectively as sinew) function as connective tissues between bone and muscle and between bone and bone, respectively. The same group repeated the study using stable isotope labeled proline and patellar tendon biopsies to detect the incorporation of newly synthesized collagen into the tendon (Hansen et al., 2009a). In the first of these studies, a group taking oral contraceptives containing moderate estradiol was compared to non-OC users in the follicular phase, when estrogen levels are naturally low, both at rest and following 1 h of kicking exercise. In professional soccer, women suffer 54% fewer muscle strains than their male counterparts (Hägglund et al., 2009). In support, Chen et al. (2014) found an estrogen dose-dependent increase in proliferation of cells from the ligamentum flavum that lasted only 24 h in culture (Chen et al., 2014). Together, these data suggest that ACL laxity changes through the cycle and eliminating the changes in estrogen using oral contraceptives decreases the risk of ACL rupture. By contrast, Carcia et al. (2004) found no change in knee displacement in relation to cycle; however, it is important to note that that these authors used self-reported cycle length to estimate menstrual phase, whereas the other studies directly measured estrogen levels in concert with knee laxity. When estrogen concentration increased during the menstrual cycle, knee laxity increased as well (Shultz et al., 2010, 2011, 2012a). Physicians prescribing testosterone could consider basic safety reminders to mitigate injury risks. As such, we examined the effects of testosterone therapy on musculoskeletal health and clinical outcomes in men. This can lead to faster and more effective recovery from fractures, particularly in individuals with low testosterone levels. While TRT primarily aids muscle recovery, it may indirectly support the healing of ligaments and tendons by improving overall tissue repair and strength. Yes, TRT can aid muscle recovery after an injury by increasing muscle protein synthesis, which helps repair damaged muscle tissues. While testosterone does play a role in maintaining muscle strength and flexibility, which are key factors in preventing injuries, the evidence is not conclusive. While TRT can help keep you strong and reduce the risk of injuries, it’s not without its downsides. Some studies have suggested that TRT could increase the risk of prostate enlargement or even prostate cancer. Sustaining recovery also means avoiding new injuries and ensuring that your body stays in good shape. This is important because strong muscles are essential for avoiding injuries, especially as you age. While more research is needed to fully understand the effects, early studies and clinical experiences provide some promising insights. For instance, when you injure a muscle, your body needs to rebuild the muscle fibers that were damaged. Your bones are not just hard structures; they are living tissues that change over time. Understanding what TRT is and how it works is the first step in making informed decisions about your health. It is important to work closely with a healthcare provider to determine which method is most suitable for your needs and lifestyle. These tests will help determine if you have low testosterone, which might justify the use of TRT. They will consider factors such as your age, medical history, and current health status. Before starting TRT, it is essential to consult with a healthcare provider, such as a doctor or a specialist in sports medicine. In men and postmenopausal women, this reaction commonly occurs in adipose tissue which is high in aromatase activity (Nelson and Bulun, 2001). The final reaction in the process is the conversion of testosterone to estradiol by the enzyme aromatase. The new gameplan for max muscle now—and the rest of your life. Sign up for muscle-building workouts, expert weight loss advice, and nutritious meal plans, delivered to your email daily. We selected adults treated with testosterone in Ontario, Canada, from October 1, 2012, to October 1, 2017 (enrollment) and continued until October 1, 2018 (follow-up). Baseline mean serum testosterone ranged from 7.5 ± 0.3 to 18.9 ± 1.2 nmol/L. As discussed above, an increase in muscle damage is consistent with an increase in tendon stiffness that decreases shielding of the muscle from strain injury. These data suggest that estrogen may increase collagen synthesis or incorporation but decrease sinew stiffness by directly inhibiting lysyl oxidase and decreasing cross-linking. In cell culture, Yu et al. (1999) found an early increase in proliferation and procollagen synthesis in freshly isolated ACL cells that were incubated with estrogen (Lee H. et al., 2015). With evidence pointing to hormonal fluctuations of the menstrual cycle having an influence on ligament injury risk, the question of how sex hormones, estrogen in particular, increase the risk of injury has been the focus of study.
