Objective: Limited data are available on the acute effects of single testosterone performance in healthy subjects. Studies of administration of testosterone to healthy subjects are rare due to their severity and the need for close clinical monitoring. However, our unique physiological experimental facilities, combined with close endocrinological collaboration, allowed us to conduct such a study safely. We tested the hypothesis that intramuscular injection of 250 mg of mixed testosterone (TE) esters improves physical performance in acute strength and power exercises, measured 24 hours after injection. Additionally, we looked at whether basal serum testosterone levels affected jumping performance (CMJ), a full 30-second sprint, and isometric elbow flexion.

Methods: In a randomized, double-blind, placebo-controlled study, 19 eugonadic men received ET (n = 9, 23 ± 1 years, 183 ± 7 cm, 83 ± 10 kg) or PLA (n = 10, 25 ± 2 years, 186 ± 6 cm, 82 ± 14 kg) injection. Hormonal levels and performance were measured in CMY, a full 30-second sprint, and isometric elbow flexion with one hand before and 24 hours after the injection.

Results: First, intramuscular injection of 250 mg mixed TE did not improve vertical jump height in the CMY test, peak power, average power, and fatigue index in the 30 second sprint. Power and maximum development speed. Voluntary contraction in isometric flexion of the elbow of one hand 24 hours after the injection. Second, it was found that baseline testosterone levels did not significantly affect strength and strength training in healthy young men.

Conclusion: A 250 mg intramuscular injection of mixed TE has no acute ergogenic effects on strength and potency in recreational young men. This new information has an impact on basic physiological understanding. Whether the same holds true for the elite athlete population remains to be seen. In this case, it would have consequences for anti-doping efforts to identify the most profitable testing programs.

introduction

Long-term administration of testosterone has well-known physiological effects, such as induction of skeletal muscle hypertrophy (Griggs et al., 1989), accelerated lipolysis and associated reduction in total body fat (Rebuffé -Scrive et al., 1991), as well as accelerated erythropoiesis (Beggs et al., 2014). ). As a result, the anabolic androgenic steroid hormone testosterone and its synthetic analogues are one of the most widely used doping agents in competitive sports (World Anti-Doping Agency, 2019; American Anti-Doping Agency, 2020) and in the ‘recreational training (Sagoe et al., 2014). In addition, long-term use of testosterone for non-therapeutic reasons may have negative health consequences, such as cardiomyopathy, dyslipidemia and hypogonadism (Pope et al., 2014), and is therefore considered not to be only as a threat to fair sport, but also a public health problem. .

Short-term use of testosterone may also have ergogenic effects, as illustrated by the increase in peak bench pressure and total work in a 10-second running cycle in nine healthy, after-trained young men. 3 weeks with intramuscular injections of 200-300 mg / week. with testosterone enanthate but not placebo (PLA), in combination with intense endurance training (Rogerson et al., 2007). However, there is limited data on whether a single dose of testosterone produces acute ergogenic effects in humans. As described by Michels and Hoppe (2008) and Foradori et al. (2008), previous studies suggest that testosterone also has a rapid, non-genomic effect (e.g. directly via ionic channels and transporters or indirectly via other messengers), which can occur on a very short time scale. (i.e. seconds, minutes and hours) after testosterone stimulation. For example, stimulation with testosterone causes a rapid increase in intracellular Ca 2+ levels in cultured rat myotubes within seconds or minutes (Estrada et al., 2003) and promotes the effects of insulin in cells. incubated human skeletal muscle fibers (Antinozzi et al., 2017), while stimulation of dihydrotestosterone, a product of testosterone metabolism, increases the production force in isolated, intact mouse skeletal muscle fibers (Hamdi and Mutungi, 2010) . Therefore, acute administration of testosterone can potentially stimulate increased production of maximal voluntary contractile force (MVC) and affect muscle energy metabolism in humans. Additionally, elevated plasma testosterone levels, measured 48 hours after administration of human chorionic gonadotropin, lower the cortical motor threshold to induce dorsal interosseous motor responses I to transcranial magnetic stimulation in healthy males (Bonifazi et al. ., 2004). This facilitates the corticospinal pathway (Bonifazi et al., 2004), which in turn can affect muscle activity and lead to faster muscle activation, which can potentially contribute to higher strength development (RFD) during voluntary movements. In this study, instead of the administration of testosterone, an intervention with endogenous production of testosterone stimulated by human chorionic gonadotropin was used, which would probably delay the onset of action compared to intramuscular injection of testosterone. . Acute testosterone treatment causes additional vasodilation (Pugh, 2003; Smith, 2008) and increased cardiac output in vitro (Smith, 2008), as well as in patients with chronic heart failure (Pugh, 2003). Carré et al. (2017) showed a rapid increase in aggressive behavior within 1 hour of a single administration of testosterone gel in men with dominant or impulsive personality styles. This can bring psychological benefits in sports. Therefore, based on the existing literature, it is possible that injecting testosterone will produce acute (seconds to hours) of performance enhancing effects that can give testosterone users a significant competitive advantage. they administer testosterone just before or during a strength and power competition. disciplines (such as weightlifting, weightlifting, jumping and sprinting). But until more research is done on humans, the effects of a single dose on human performance will remain speculative. If such studies are carried out

There would have been remarkably positive correlations between resting serum testosterone levels, vertical jump height (Bosco et al., 1996; Cardinale and Stone, 2006) and sprint performance (Bosco et al., 1996) in elite athletes in various sports. . suggests that athlete performance may be linked to individual differences in basal testosterone levels. Therefore, the magnitude of the effect of such a single testosterone injection may be due to the initial testosterone level, which causes a weakened biological effect in people with naturally high testosterone levels. Accordingly, we tested the hypothesis that baseline serum testosterone levels affect CMJ performance, a full cycle speed of 30 seconds, and isometric elbow flexion in recreational men.

An assessment of these issues would provide new information for a basic physiological understanding of testosterone. In addition, knowledge of the performance enhancing effects of a doping substance is important for anti-doping authorities. While long-term administration of testosterone increases the risk of detection by anti-doping authorities and in private sports leagues outside the jurisdiction of the World Anti-Doping Agency (WADA), the detection of short-term use or even a single dose requires sampling. This is associated with increased discomfort for the athlete, as well as increased costs of sampling and analysis. Therefore, information about the possible acute effects of testosterone is of great importance when anti-doping authorities determine the most cost-effective testing programs.