https://matteocampagna.com/en/registry/health/menstrual-cycle-competition-period Changes to this claim in Matteo Campagna's evidence registry: its status, its year-by-year history, revisions of the page. en-gb https://matteocampagna.com/en/registry/health/menstrual-cycle-competition-periodThe only data come from a questionnaire, and they should be read as such. At the 2019 Turkish championship, 142 women archers with an average age of 25 described their cycle twice: in general 53.5% called it regular, 21.8% sometimes regular and 24.6% irregular; for the competition period, 27.5% regular, 50% sometimes regular and 22.5% irregular. There is a shift, but it has a particular shape: the "regular" answers halve and the "sometimes regular" answers grow by almost as much, while the share calling it irregular does not grow. The two answers were not compared with a statistical test and come from the same athletes' recollection, gathered at a single point in time; the paper does not say what it means by the competition period or who was using hormonal contraception, and within the same table the age bands hold 39, 54 and 49 athletes for the first question and 30, 51 and 61 for the second. The link with competition stress is the author's hypothesis, which the study does not examine. Finally, the journal has questionable editorial standards: the registry reports the study but does not use it to decide the status, which remains not studied.claim:ciclo-mestruale-periodo-gare:revision:2026-09-22:2Tue, 22 Sep 2026 08:00:00 GMT https://matteocampagna.com/en/registry/health/menstrual-cycle-competition-periodclaim:ciclo-mestruale-periodo-gare:new_claim:2026-08-08:non_studiatoSat, 08 Aug 2026 08:00:00 GMT