The influence of the menstrual cycle and hormonal contraceptives on cardiorespiratory fitness in physically active women: A systematic review and meta-analysis.

Objective: To systematically review and summarize the existing evidence related to the influence of the menstrual cycle (MC) and hormonal contraceptive (HC) use on V˙O2max in physically active women. Methods: This systematic review and meta-analysis conforms to the PRISMA statement guidelines. Four (sub-)meta-analyses were performed. Two focused on longitudinal studies examining the same women several times to compare the V˙O2max during the different menstrual phases or oral contraceptive (OC) use and withdrawal. Two meta-analyses examined if there is a difference in V˙O2max between OC users and normally menstruating women by analyzing cross-sectional studies assigning physically active women to one of these two groups as well as intervention-based studies (cross-over studies, randomized controlled trials considering only the data of the intervention group) comparing women intra-individually with and without OCs. Results: Nine of the included studies (107 women) evaluated the influence of the MC, five studies (69 women) the impact of OCs on V˙O2max, and six studies investigated both topics (88 women). A mean difference of V˙O2max -0.03 ml/kg/min (95%CI -1.06 to 1.01) between the early follicular and luteal menstrual phase was observed. Between the active and inactive phases of OCs, a mean difference of -0.11 ml/kg/min (95%CI -2.32 to 2.10) was found. The inter-individual comparison of naturally menstruating women and OC users showed a mean difference in V˙O2max of 0.23 ml/kg/min (95% CI -2.33 to 2.79) in favor of OC use. The intra-individual comparison of the same women showed a mean decrease in V˙O2max of -0.84 ml/kg/min (95% CI -2.38 to 0.70) after a new start with OCs. Conclusions: Our meta-analyses showed no effects of the MC or the OCs on V˙O2max. More high-quality studies are needed determining the MC phases more precisely, including OCs with the current standard formulations and comparing the influence of different progestins.

Period prevalence of SARS-CoV-2 infections and willingness to vaccinate in Swiss elite athletes.

Objectives: (1) To assess the period prevalence of SARS-CoV-2 infections and willingness to vaccinate in Swiss elite athletes and (2) to evaluate whether sociodemographic and sport-related characteristics were associated with infection of SARS-CoV-2 in athletes. Methods: A total of 1037 elite athletes (Mage=27.09) were surveyed in this cross-sectional study. They were asked whether they had been infected with SARS-CoV-2 and whether they would like to be vaccinated. Characteristics of a possible COVID-19 illness were also recorded. Results: During the first year of the pandemic, 14.6% of all Swiss elite athletes were found to be infected with SARS-CoV-2, and 5.4% suspected that they had been infected. Male athletes, young athletes and team sports athletes had an increased likelihood of being infected with SARS-CoV-2. There was considerable heterogeneity in the duration and severity of a COVID-19 illness in athletes. Overall, 68% of respondents indicated a willingness to be vaccinated if they were offered an opportunity to do so. Conclusion: In the first year of the pandemic, Swiss elite athletes were tested more often positive for SARS-CoV-2 than the general Swiss population. Because COVID-19 illness can impair health for a relatively long time, sports federations are advised to motivate athletes to be vaccinated.