Estradiol

17β-Estradiol (E2) is the most potent endogenous oestrogen, produced mainly by ovarian granulosa cells and by peripheral aromatisation of testosterone, regulating the menstrual cycle, bone mineral density, substrate metabolism, and connective-tissue properties. Salivary estradiol captures the free, bioavailable fraction relevant to menstrual-phase effects on performance, recovery, and injury risk, and to detecting the low energy availability of RED-S. Elliott-Sale et al. (2020) and De Souza et al. (2010) established salivary oestrogen monitoring as central to female-athlete health.