# less than half of the studies on menstrual cycle & exercise performance measured hormone concentrations - recent literature on exercise performance over the menstrual cycle identified through a literature search of PubMed and SportDiscus from 2008 until 2018. - only 44% of the selected studies measured the actual concentrations of the female steroid hormones estrogen and progesterone - It was shown that the likely inclusion of participants with anovulatory or luteal phase-deficient cycles in combination with small participant numbers has affected results in recent menstrual cycle research and, consequently, our understanding of this area. [[(Janse DE Jonge, Thompson and Han, 2019)#^jw32h]]