Although scarce , the data available to date suggest that hyper and rogenism , such as that observed in PCOS , may likely be associated with oligomenorrhoea in exercising women , and may not always represent hypothalamic inhibition secondary to an energy deficiency .
To date , the predominant mechanism underlying  menstrual disturbances in exercising women supports an underlying energy deficiency-related aetiology , in which a failure to compensate dietary intake for the energy cost of exercise suppresses reproductive function .
Increasing evidence demonstrates that energy deficiency plays a causal role in the induction of amenorrhoea in  exercising women , and consistent with this mechanism are findings of glucoregulatory perturbations such as low triiodothyronine , reduced insulin secretion and elevated cortisol , growth hormone and ghrelin levels .
The menstrual disturbance that may differ in its energetic characteristics and , perhaps in its and rogenic and ovarian steroid environment , is oligomenorrhoea .
We conducted a systematic review of the literature to begin to underst and whether oligomenorrhoea in  exercising women is a mild sub clinical phenotype of polycystic ovarian syndrome ( PCOS ) in which exercise is conferring beneficial effects in protecting women from the classic PCOS phenotype , or whether oligomenorrhoea is part of the spectrum of menstrual disturbances caused by an energy deficiency that is often reported in exercising women with menstrual disturbances .
Hormonal profile of women with self-reported symptoms of oligomenorrhea and/or hirsutism: Northern Finland birth cohort 1966 study.
The hormonal profiles of nested female patients ( n = 500 ) with self-reported symptoms typical of polycystic ovary syndrome ( PCOS ) , oligomenorrhea , and /or hirsutism and their r and omly selected controls ( n = 1026 ) at the age of 31 yr were analyzed in a general population -based Northern Finl and birth cohort 1966 to find out whether the symptomatic women also have the endocrine characteristics of PCOS and could be detected in a general population using simple questions . Higher medians of serum testosterone ( T ) ( 2.10 vs. 1.90 nmol/liter , P < 0.001 ) , LH ( 5.40 vs. 4.85 U/liter , P = 0.005 ) , insulin ( 53.8 vs. 51.66 pmol/liter , P = 0.040 ) , and free and rogen index ( FAI ) ( 4.01 vs. 3.03 , P < 0.001 ) and lower glucose/insulin ratio ( 91.1 x 10(8 ) vs. 94.9 x 10(8 ) , P = 0.048 ) and SHBG ( 52.4 vs. 60.7 nmol/liter , P < 0.001 ) were observed among the cases , but no difference was observed in cortisol and glucose levels between the cases and controls . Of all the women in the cohort , 10.2 % reported only oligomenorrhea and had biochemical findings similar to the whole case group . Those who reported only hirsutism ( 10.4 % ) were in between the case and control groups according to biochemical findings . The subjects who reported both oligomenorrhea and hirsutism ( 3.4 % ) had the highest T , LH , FAI , insulin , and glucose and the lowest SHBG and glucose/insulin ratio , compared with the case group and the groups with either symptom only indicating a dose-response manner in typical endocrine profile of PCOS by adding up symptoms . The levels of T and FAI were higher and SHBG lower in groups with overweight or obesity both at 14 and 31 yr , compared with groups with normal weight at 14 yr and overweight or obesity at 31 yr . In the group with normal weight at 14 and 31 yr and the group with overweight or obesity at 14 yr but normal weight at 31 yr , the levels of T and FAI were lowest and SHBG highest . T and FAI were higher and SHBG lower among the cases than the controls in groups stratified by weight development from adolescence to adulthood . In conclusion , this longitudinal study of a large , stable population indicates that women with self-reported symptoms of hirsutism and /or oligomenorrhea show endocrine characteristics of PCOS and can be detected in a general population using simple questions . These symptoms are markers of the underlying metabolic alterations possibly associated with increased health risks in later life
Although scarce , the data available to date suggest that hyper and rogenism , such as that observed in PCOS , may likely be associated with oligomenorrhoea in exercising women , and may not always represent hypothalamic inhibition secondary to an energy deficiency .
To date , the predominant mechanism underlying  menstrual disturbances in exercising women supports an underlying energy deficiency-related aetiology , in which a failure to compensate dietary intake for the energy cost of exercise suppresses reproductive function .
Increasing evidence demonstrates that energy deficiency plays a causal role in the induction of amenorrhoea in  exercising women , and consistent with this mechanism are findings of glucoregulatory perturbations such as low triiodothyronine , reduced insulin secretion and elevated cortisol , growth hormone and ghrelin levels .
The menstrual disturbance that may differ in its energetic characteristics and , perhaps in its and rogenic and ovarian steroid environment , is oligomenorrhoea .
We conducted a systematic review of the literature to begin to underst and whether oligomenorrhoea in  exercising women is a mild sub clinical phenotype of polycystic ovarian syndrome ( PCOS ) in which exercise is conferring beneficial effects in protecting women from the classic PCOS phenotype , or whether oligomenorrhoea is part of the spectrum of menstrual disturbances caused by an energy deficiency that is often reported in exercising women with menstrual disturbances .