participates in structured running or cycling exercise for at least 30 minutes on 3 or more days per week
accustomed to exercising for 90 minutes or more
has regular periods every 21-35 days
have not taken hormonal contraceptives for at least the past 6 months
is not currently or trying to become pregnant or breastfeeding, and has not been pregnant or breastfeeding in the past 12 months
does not currently have a diagnosis of a major menstrual cycle disorder (i.e., amenorrhea, polycystic ovary syndrome \[PCOS\], endometriosis, ovarian cancer, ovarian insufficiency, uterine or endometrial cancer)
does not currently have a metabolic disease (i.e., hypothyroidism, hyperthyroidism, Cushing disease, Addison's disease, diabetes, congenital adrenal hyperplasia)
does not currently have a major cardiovascular or respiratory disease
You may not be if
miss more than 7 consecutive days of aerobic activity (i.e., running, cycling, cross training)
demonstrate clinical low energy availability as defined as energy availability \<30 kcal/kg fat free mass
report menstrual cycle lengths \<21 or \>35 days in the first 2 months of at-home monitoring
do not demonstrate an anticipated rise in luteinizing hormone and progesterone in the first 2 months of at-home monitoring
begin taking a hormonal contraceptive
become pregnant
are diagnosed with a menstrual cycle disorder (i.e., amenorrhea, polycystic ovary syndrome \[PCOS\], endometriosis, ovarian cancer, ovarian insufficiency, uterine, or endometrial cancer)
are diagnosed with a metabolic disease (i.e., hypothyroidism, hyperthyroidism, Cushing disease, Addison's disease, diabetes)
are diagnosed with a major cardiovascular or respiratory disease
are unable to follow instructions for any of the procedures
