Prolonged Effects of Elevated 17β-Estradiol on Physical Activity after Orchidectomy

Abstract

Wheel running behavior was reduced significantly after orchidectomy and remained low after initial treatment with estrogens, but recovered to near control levels after 2 wk of exposure to estrogens. The estrogenic mechanism regulating wheel running behavior in male mice appears to induce an extensive but slow acting biological mechanism. Understanding the biological drive behind this mechanism may aid in developing useful therapeutic strategies to combat health issues related to physical inactivity.

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“…It is likely that in TW athletes, and also depending on individual AR responsiveness [119], testosterone reduction cannot reset muscles to a female phenotype [102,103,108,109] as testosterone suppression must not necessarily reach female serum testosterone concentrations (i. e., < 1.8 nmol/L) in all TW athletes, both prior to and during competitions, and because muscle memory for testosterone still stimulates fibers hypertrophy in response to mechanical loads [120,121]. Furthermore, estrogen administration at relatively high doses for the 46XY gender also has a strong influence on muscle structure and physiology, attenuating the devirilization of the body's muscles [15,25,122,123]. Many biological and functional differences between treated TW and eugonadal cisgender athletes exist (▶ Table 6), as not all gene-related gender characteristics can be partially or completely reversed by GAHT.…”

Clinical Concerns on Sex Steroids Variability in Cisgender and Transgender Women Athletes

“…It is likely that in TW athletes, and also depending on individual AR responsiveness 119 , testosterone reduction cannot reset muscles to a female phenotype 102 103 108 109 as testosterone suppression must not necessarily reach female serum testosterone concentrations (i. e., <1.8 nmol/L) in all TW athletes, both prior to and during competitions, and because muscle memory for testosterone still stimulates fibers hypertrophy in response to mechanical loads 120 121 . Furthermore, estrogen administration at relatively high doses for the 46XY gender also has a strong influence on muscle structure and physiology, attenuating the devirilization of the body’s muscles 15 25 122 123 . Many biological and functional differences between treated TW and eugonadal cisgender athletes exist ( Table 6 ), as not all gene-related gender characteristics can be partially or completely reversed by GAHT.…”