No significant difference in the use of the S2 class between women and men was observed in our data. Short-term use of rhEPO markedly improves endurance capacity in male athletes, and this is identified by a significant increase in VO₂ max or maximal aerobic power in running or cycling trial performances (Salamin et al., 2018; Sgrò et al., 2018; Haile et al., 2019). For this reason, rhEPO analyses focus on aerobic sports and, unsurprisingly, we found all rhEPO cases in either endurance or mixed sports. It is generally assumed that the main part of performance improvement with rhEPO administration is related to blood adaptations that enable higher oxygen transport. Unfortunately, to our knowledge, no study on performances in female athletes has been conducted, even though their lower blood volume, red blood cell number, and hemoglobin level probably modulate the stimulating effect on erythropoiesis. Regarding the side effects, they appear to be much more limited in the short term since the advent of micro-dose administration, but here again, data exist only for male athletes (Salamin et al., 2018). In a study on young healthy sedentary volunteers, however, Gambardella et al. (2016) suggested that the rhEPO effects might be confined to the vascular wall in males, with stabilization of the thrombi, whereas its effects in females can be observed in the peripheral circulation, with possible high blood thrombogenicity that merits more careful medical attention to female athletes. Nevertheless, rhEPO accounted for all the AAF in females for this S2 class, contrarily to males. Caution is warranted here in view of the small number of analyses carried out, but it could be suggested that the other S2 substances used by male athletes, i.e., hypoxia-inducible factors, GH, LH and their releasing factors, may induce either less ergogenic or more marked side effects in women. Given the difficulty of obtaining approval from the Ethics Committees for the administration of rhGH in athletes, few studies have investigated its ergogenic effects in trained subjects (Berggren et al., 2005; Marchand et al., 2019), with only one in females (Berggren et al., 2005). The authors reported no change in maximal oxygen uptake or maximum power output during exercise with rhGH use (Berggren et al., 2005; Marchand et al., 2019), and also increased body weight that was attributed to fluid retention and not muscle mass (Berggren et al., 2005). Despite these results, the rhGH impact on both anaerobic and aerobic performance is not in doubt, due to its direct and indirect anabolic (Holt and Sönksen, 2008; Siebert and Rao, 2018) and lipolytic effects (Healy et al., 2006) with, in terms of IGF-1, a greater response to rhGH treatment in men (Giannoulis et al., 2005). Although it remains unknown whether the cardiovascular, metabolic, and neuropsychiatric side effects reported in patients with chronic GH treatment occur in athletes (Siebert and Rao, 2018), short-term supra-physiological rhGH treatment was shown to induce central hypothyroidism in both male and female recreationally trained athletes from various team sports, but with distinct gender-related patterns, probably due to modulation of gonadal steroids on the GH-IGF-1 axis (Sgrò et al., 2016). Last, it should be recalled that, given the small number of GH analyses and the very short elimination half-time of rhGH (Giannoulis et al., 2005), the number of positive cases probably greatly underestimates actual use by athletes, irrespective of gender.