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 .
Changes in glucose tolerance over time in women with polycystic ovary syndrome: a controlled study.
We performed this study to access the changes in glucose tolerance over time in a group of women with polycystic ovary syndrome ( PCOS ) ( n = 71 ) and control women ( n = 23 ) with regular menstrual cycles and baseline normal glucose tolerance . Mean follow-up was between 2 and 3 yr for both groups ( PCOS 2.5 + /- 1.7 yr ; controls 2.9 + /- 2.1 yr ) . Based on World Health Organization glucose tolerance categories , there was no significant difference in the prevalence of glucose intolerance at follow-up in the PCOS group . In the PCOS group , 25 ( 37 % ) had impaired glucose tolerance ( IGT ) and seven ( 10 % ) had type 2 diabetes mellitus at baseline , compared with 30 ( 45 % ) and 10 ( 15 % ) , respectively , at follow-up . There were also no differences within groups ( PCOS or control ) or between groups ( PCOS vs. control ) in the oral glucose tolerance test-derived measure of insulin sensitivity , but in the women with PCOS who converted to either IGT or type 2 diabetes mellitus , there was a significant decrease ( P < 0.0001 ) . At the follow-up visit , the mean glycohemoglobin level was 6.1 + /- 0.9 % in women with PCOS vs. 5.3 + /- 0.7 % in the control women ( P < 0.001 ) . Women with PCOS and baseline IGT had a low conversion risk of 6 % to type 2 diabetes over approximately 3 yr , or 2 % per year . The effect of PCOS , given normal glucose tolerance ( NGT ) at baseline , is more pronounced with 16 % conversion to IGT per year . Our study supports that women with PCOS ( especially with NGT ) should be periodically rescreened for diabetes due to worsening glucose intolerance over time , but this interval may be over several years and not annually
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 .