The inclusion of a 0 (placebo) dose allowed differentiation between the 0 and lowest testosterone dose. Cohorts 1 and 2 were treated with the same increasing doses of testosterone but either without (green fill, cohort 1) or with (purple fill, cohort 2) an aromatase inhibitor (anastrozole), which prevents conversion of testosterone to estradiol. However, androgen-resistant females can be bred by genetic engineering using the Cre-Lox system (100). This is because fully androgen-resistant females must have both X chromosomes carrying an inactivated AR. The converse, genetic females (46,XX) resistant to all androgen action cannot occur naturally in humans or other mammals. Genetic males (46,XY) with androgen insensitivity displaying similar features occur through the spontaneous production of inactivating AR mutations in all mammalian species studied, including humans, where they are known as women with CAIS. Hence, the only feasible design of such studies would be testosterone (or another androgen) administration to healthy young women. Alternatively, carefully controlled, graded-dose studies in F2M transgender individuals might be informative but are largely lacking at this time. The prediction is supported by the anecdotal evidence from the surreptitious East German national doping program in which the supervising doctors asserted from their experience of illicit cheating that androgens had more potent ergogenic effects in women than in men (120), a speculative opinion shared by many experienced sports medicine physicians. Congruent findings are also known for an elite female athlete whose serial athletic performance based on publicly available best annual times between 2008 and 2016 for the 800-m running event are depicted in relationship to the original 2011 IAAF hyperandrogenism regulation (Fig. 8). Subsequently, when the IAAF hyperandrogenism rule was suspended in 2015, and so these elite athletes could train and compete with unsuppressed serum testosterone levels, their athletic performances increased by a similar amount. Those findings cannot explain the male advantage in muscle mass and strength unless GH retards muscle growth/function, for which there is no evidence. Currently, in Australia, nearly 730,000 adults engage in surfing, and it is believed these numbers align with worldwide participation rates for which it is thought that more than 50 million people engage in surf sports (2). In Australia alone, between 2019 and 2021, 196,000 new participants registered as competitors with formal surfing clubs (1). We argue that the improved thermal profile may have influenced power and, as such, surfing performance was enhanced. Therefore, the aim of this study was to explore the effectiveness of a warm-up in terms of readiness to perform in surfing. In numerous land-based sports, and in swimming, the importance of a warm-up and muscle heat is well documented. Given surfing's inclusion as an Olympic sport from the 2020 Tokyo Olympics onwards, an examination of performance would seem useful. Surfing is a high participation sport, yet little sport science research exists regarding competitive performance in surfing. Adult height displays an apparent dose dependency on SHOX gene copy number that is a major factor contributing to explaining both the short stature of 45,XO females (Turner syndrome), who have a single copy of the SHOX gene, as well as the tall stature of 47,XXY males (Klinefelter syndrome), who have three copies (161). Taller height is advantageous in some sports (basketball, some football codes, combat sports), but in others (horse racing jockeys, cycling, gymnastics, weightlifting, bodybuilding) short stature provides a greater power/strength-to-weight ratio as well as superior rotational balance, speed, and agility. There is some limited direct evidence from well-designed, placebo-controlled trials that administration of testosterone or other androgens at supraphysiological doses directly affect mood and behavior, notably inducing hypomania (153). Psychological differences between men and women on mental function (e.g., rotational orientation) (150) as well as mood, motivation, and behavioral effects may involve androgen-sensitive effects during prenatal and perinatal as well as postpubertal effects (151, 152). Further physiological studies of the androgen dependence of other physiological sex differences are awaited with interest. Hence, such direct investigational studies in otherwise healthy women would risk side effects of virilization that may be only slowly and partly reversible, if at all, as well as potential promotion of hormone-dependent cancers making such studies ethically and practically not feasible. Bone density (total and medullary cross-sectional area) is increased in women with CAH with variably elevated serum testosterone (including into the male range) when it is only partially suppressed by glucocorticoid treatment (143), although more effective glucocorticoid suppression lowers bone density (144). The nutritional profile of what one consumes can directly influence hormonal balance, especially when it comes to testosterone. Natural boosters, on the other hand, are safer but take longer to show effects. While synthetic options offer faster results, they might come with side effects and require medical supervision. Programs like Metabolic Renewal focus on optimizing overall health, including hormonal balance, to help athletes perform at their peak, ensuring they stay in tune with their body’s natural rhythms. For surfers, endurance is the key to mastering the waves, whether it's paddling out against strong currents or maintaining balance on a tricky wave. With the right combination of training, supplementation, and gear, surfers can optimize their performance both in and out of the water, ensuring they are ready to take on whatever the ocean throws their way. Maintaining a balance in hormones can significantly impact a surfer’s stamina, enabling them to ride waves longer and more effectively. An 11% increase in circulating hemoglobin translates to a 10% difference in maximal oxygen transfer (124), which may account for virtually all the 12% sex difference in male and female circulating hemoglobin (125). The women whose testosterone concentrations were increased to 7.3 nmol/L achieved significant increases in muscle mass and strength (Table 4), ranging from 4.4% for muscle (lean) mass to between 12% and 26% for measures of muscle strength (chest and leg press, loaded stair climb). Owing to ethical concerns regarding risks of unwanted virilization and hormone-dependent cancers, however, few studies have administered supraphysiological testosterone doses to healthy women. This again created a graded dose-response curve for serum testosterone and for muscle mass and strength. The athletes displayed higher muscle (and bone) mass than did the sedentary control women, with strength tests correlating strongly with muscle mass whether in total or just in the legs. Note that in the same dataset, female serum testosterone concentrations did not change over those ages, remaining the same as in prepubertal boys and girls. Note the systematic overestimation of testosterone by the immunoassay used in cohort 1 vs LC-MS measurement in cohort 2. It may be estimated that as a result the average maximal oxygen transfer will be ∼10% greater in men than in women, which has a direct impact on their respective athletic capacities.Open in a new tabRedrawn results from Ekblom et al. (124). Hepcidin has to balance the need for iron absorption from foods (the only source of iron required for the body’s iron-containing proteins) against the fact that the body has no mechanism to shed excess iron, which can be toxic. Testosterone increases secretion of and sensitivity to erythropoietin, the main trophic hormone for erythrocyte production and thereby hemoglobin synthesis, as well as suppressing hepcidin (122), a crucial iron regulatory protein that governs the body’s iron economy. In turn, this requires acquiring one X chromosome from their father, and hemizygous males bearing a single X chromosome with an inactive AR produce no sperm, as a functional AR is biologically indispensable for making sperm in any mammal. Hence, whereas gender is usually consistent with biological sex as assigned at birth, in a few it can differ during life. Sex is an objective, specific biological state, a term with distinct, fixed facets, notably genetic, chromosomal, gonadal, hormonal, and phenotypic (including genital) sex, each of which has a characteristic defined binary form. Less attention is given to the philosophical basis of fair competition in elite sports, where the objectives are not egalitarian but aim to discover a hierarchy of achievement derived from a mixture of unequal natural talent and individual training effort. These considerations affect sports through the universal application of antidiscrimination and human rights legislation. For example, until the late 19th century when organized sports trainers emerged, training itself was considered a breach of fairness because competition was envisaged at that time as a contest based solely on natural endowments. In the absence of genuine fair competition, elite sports would lose their wide popular appeal and ability to captivate and inspire with the authentic attraction of genuine contest between highly trained athletes.
