We conclude that the initiation of strenuous endurance training in previously ovulating untrained women frequently leads to corpus luteum dysfunction associated with insufficient progesterone secretion and, in the case of short luteal phase cycles, decreased luteal phase length. That exercise may alter the neuroendocrine system is suggested by a delay in the ovulatory LH peak in spite of increased estriol (estrogen) excretion; moreover, less LH is excreted during the luteal phase. The lack of positive feedback to estrogens and decreased LH secretion during the luteal phase could compromise corpus luteum function.
http://www.ncbi.nlm.nih.gov/pubmed/1902847
In the prospective study, exercise reduced pregnanediol glucoronide (a measurement of progesterone) and peak E1G (a measurement of estrogen) levels. Moderate aerobic exercise may lessen late luteal phase ovarian hormone levels.
http://www.ncbi.nlm.nih.gov/pubmed/17039366
After three months, women in the exercise group had a 7 percent decrease in the level of estradiol, the most potent blood estrogen, while women in the stretching group had no change in estradiol levels. Among exercisers, there was a 4 percent decrease in estrone levels compared with a 3 percent increase in controls, and the difference was statistically significant. Exercisers who lost more than 2 percent of their initial body fat had a 14 percent decrease in estradiol levels. Controls who lost body fat, however, did not experience a decrease in estradiol levels.
http://www.aphroditewomenshealth.com/news/20030123215938_health_news.shtml
Strenuous but not moderate physical activity at age 12 was inversely associated with pre- and postmenopausal breast cancer risk across estrogen receptor/progesterone receptor subtypes [overall odds ratio (>/=5 days/week vs. none) = 0.24]. Moderate physical activity in the previous 5 years was significantly associated with a decrease in risk for postmenopausal estrogen receptor + progesterone receptor + tumors only [odds ratio (>/=1 day/week vs. none) = 0.35].
http://www.ncbi.nlm.nih.gov/pubmed/20607384
Free testosterone showed a decreasing trend of 19-25% with 6 weeks of training on 6 days a week in recreational athletes. Cortisol release was reduced, follicle-stimulating hormone (FSH)-synthesis-secretion capacity was increased after training, and the luteinizing hormone (LH)-synthesis-secretion capacity reduced.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1332185/
SHBG increased (from 27.5 to 34.7 nM) whereas testosterone/SHBG decreased significantly (from 1.10 to 0.85). Serum total testosterone and cortisol did not change significantly in a group of 19 elite weight lifters after 20 weeks of training.
http://www.ncbi.nlm.nih.gov/pubmed/20533100
Concentrations of testosterone and free testosterone among exercisers who lost between 0.5% and 2% body fat declined by 4.7% and 10.4%. In controls who lost this amount of body fat, concentrations of testosterone and free testosterone declined by only 2.8% and 4.3%.
http://cebp.aacrjournals.org/content/13/7/1099.abstract
Engaging in more than eight hours of sporting activity per week caused a significant decrease in the frequency of self-reported acne, dysmenorrhea, and menstrual irregularities.
http://www.thorne.com/altmedrev/.fulltext/6/3/272.pdf
Menstrual Cycle and Miscarriage
We examined the effects of exercise on plasma total homocysteine concentrations in young overweight or obese PCOS women. (23.8 ± 5.0 min of brisk walking per day). A significant decrease in plasma total homocysteine concentrations (10.06 to 7.36 µmol/liter) and a significant increase in maximal oxygen consumption were recorded at 6 months, compared with baseline in the exercise group. This decrease in homocysteine was not explained by changes in anthropometric or biochemical parameters. In contrast, no significant changes in any of the variables were observed in the nonexercise group. In both groups of women, blood levels of vitamin B12, folate, free T4 , insulin, and creatinine, factors known to influence homocysteine levels, were not significantly different between baseline and observation at 6 months. In multiple variable models, only age in years was statistically significantly associated with homocysteine levels.
http://jcem.endojournals.org/cgi/reprint/87/10/4496.pdf
Our results show that higher plasma concentrations of total homocysteine after an acute intense exercise are associated to higher concentrations of reduced homocysteine, and this effect is independent of the type of exercise, vitamin status, or amino acid metabolic stress but could be related to potential changes in the renal function.
http://www.ncbi.nlm.nih.gov/pubmed/19568194
Recent research suggests that intense, long duration exercise raises plasma homocysteine levels, perhaps by increasing the load on methionine metabolism.
http://www.scipub.org/fulltext/ajbb/ajbb62116-119.pdf
Physical fitness is not related to lower homocysteine
In this sample no association was found between level of cardiorespiratory fitness and plasma total homocysteine in men or women.
http://www.ima.org.il/imaj/ar09feb-03.pdf
Previously sedentary nonobese patients were enrolled in a resistance training group or used as sedentary control subjects. The training program consisted of two sets of nine exercises with 10-20 repetitions. Subjects trained five times a week for 4-6 weeks. The glucose disposal rate increased 48% in the resistance training group (6.85 to 10.12 mg.kg-1 lean body mass.min-1), but remained unchanged in the sedentary group (5.95 to 6.36 mg.kg-1 lean body mass.min-1). There was no significant change in body composition in either group. In the resistance training group, a 16% increase in quadriceps strength (191.1 to 216.9 Nm) but no significant change (27.6 to 28.6 ml.kg-1.min-1) in VO2max was observed.
http://www.ncbi.nlm.nih.gov/pubmed/9702447
HbA1c (a measure of insulin resistance) fell significantly more in the resistance training & weight loss group than weight loss plus a control program group at 3 months (0.6 vs. 0.07%) and 6 months (1.2 vs. 0.4%) (HbA(1c) is measured in percentage, >6.5% is considered diabetic). Similar reductions in body weight and fat mass were observed after 6 months.
http://care.diabetesjournals.org/content/25/10/1729.full
Significant reductions in fasting insulin were observed in the resistance training group.
http://www.ncbi.nlm.nih.gov/pubmed/20531348
In the 13 randomized controlled trials included in our analysis, resistance training reduced glycosylated haemoglobin (HbA(1c)) (a measurement of blood sugar control - lower is better) by 0.48% (HbA(1c) is measured in percentage, >6.5% is considered diabetic), fat mass by 2.33 kg and systolic blood pressure by 6.19 mmHg. There was no statistically significant effect of resistance training on total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride and diastolic blood pressure.
http://www.ncbi.nlm.nih.gov/pubmed/20433212
The plasma visfatin levels (294 ng/ml to 186 ng/ml) and insulin resistance were significantly reduced after 12 wk of aerobic exercise. The results suggest that aerobic exercise resulting in an energy expenditure of 1,200-1,600 kcal/wk for 12 wk decreases plasma visfatin and insulin resistance in obese female adolescents.
http://www.ncbi.nlm.nih.gov/pubmed/20739715
Cortisol release was reduced with 6 weeks of training on 6 days a week in recreational athletes. Free testosterone showed a decreasing trend of 19-25%, and LH release was reduced. These changes were still observed after 3 weeks of recovery.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1332185/
After maximal exercise we found a significant reduction of activated partial thromboplastin time and thromboplastin time, a decrease in antithrombin III, von Willebrand factor-concentration, fibrinogen, plasminogen and alpha2-antiplasmin but an increase in fibrinolytic activity (the ability of some proteolytic enzymes to dissolve the fibrin in blood clots). After the physical conditioning program (12 weeks of aerobic conditioning) an increase in fibrinolytic activity at rest was noted in the training group. Opposed to that the fibrinolytic activity at rest decreased in the control group after abstinence of sports activity over this period.
http://www.ncbi.nlm.nih.gov/pubmed/11235004
Exercise and Hormones, Exercise and Pregnancy
For a concise list of qualities found to affect one's risk of miscarriage, see: Causes of Miscarriage