Estrogen and Exercise

Most people associate exercise with mental well-being, weight loss and better health. Yet few know about the hormonal benefits of exercise. Estrogen and other hormones can be naturally balanced by physical activity, reducing the risk of breast cancer and other diseases.

Estrogen plays a key role in reproduction, musculoskeletal function and brain health. Even the slightest imbalance can trigger a chain reaction in your body. Estradiol, estriol and estrone, the three most important estrogens, are particularly important and have a direct influence on the reproductive system, points out the U.S. National Library of Medicine.

These sex hormones are produced by the ovaries, adrenal glands and fat cells. Besides its role in reproductive health, estrogen affects your skin, hair, bones, breasts and brain, explains the University of Rochester Medical Center. It also supports bone health, influences lean mass and promotes collagen production in the connective tissues, so it can play a major role in sports performance. Too much of it can be harmful, though.

A review published in ​Frontiers in Physiology​ in January 2019 notes that high estrogen levels may impair sports performance in women and increase injury risk. According to the Medical University of South California, excess estrogen may contribute to some autoimmune diseases. It can also raise the risk of fibroids, obesity, anxiety, depression and fatigue in women, according to the Endocrine Society.

Men with high estrogen may experience an increase in breast size. Infertility and sexual problems can also occur. Too little estrogen, however, may affect libido in men and promote fat accumulation in the abdominal area. Women who have low estrogen levels may experience difficulty sleeping, dry skin, hot flashes and cessation of menstruation.

Estrogen levels are strongly affected by exercise. Physical activity may help lower estrogen and bring your hormones back into balance. For example, a May 2013 study published in ​Cancer Epidemiology, Biomarkers and Prevention​ has found that aerobic exercise may improve estrogen metabolism and protect against breast cancer, a disease associated with high estrogen levels, among other factors.

The study was conducted on healthy premenopausal women and involved 150 minutes of moderate-to-vigorous aerobic exercise per week for four months. Subjects also experienced a significant reduction in body fat mass and improvements in cardiovascular fitness.

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Another study, which was featured in ​Endocrine-Related Cancer​ in October 2015, tried to determine how much exercise is required to lower breast cancer risk in postmenopausal women. One group was prescribed 150 minutes of aerobic exercise per week, while the other group completed 300 minutes of aerobic training.

Both groups experienced similar changes in estrogen levels. As the researchers note, the hormonal benefits of exercise on estrogen levels may be due to weight loss. Dietary changes may amplify these effects.

High-intensity exercise is even more effective, reports a review published in ​Breast Cancer Research​ in November 2015. After analyzing the results of more than 20 studies, scientists concluded that physical activity can reduce estrogen and other sex hormones in women. These effects were more noticeable in women who did not have obesity and those who engaged in high-intensity training, regardless of weight loss induced by exercise.

Physical activity may also have some benefit for women with obesity and polycystic ovary syndrome (PCOS), explains a review featured in the ​International Journal of Endocrinology​ in July 2012. Obesity doesn't directly cause PCOS, explains a December 2012 article in ​Seminars in Reproductive Medicine​, but it's a major risk factor and may worsen its symptoms. Exercise can help you lose weight and keep the pounds off.

A small clinical trial confirms the relationship between female hormones and weight lifting. As it turns, strength training may improve estrodiol levels and quality of life in postmenopausal women with osteoporosis. These findings were published in the ​International Journal of Health Sciences​ in the July-August 2019 issue.

More isn't necessarily better when it comes to exercise. Adipose tissue produces estrone, a hormone that supports the reproductive function. Therefore, low body-fat levels may affect estrogen production and put you at risk of early menopause and infertility, states a review published in ​Human Reproduction​ in December 2017. The risk of early menopause is about 30 percent higher in women with underweight compared to those with a normal weight.

Low estrogen production may also increase your odds of osteoporosis, notes the Endocrine Society. As discussed earlier, this hormone plays a key role in bone health. While it's true that regular exercise keeps your bones healthy, too much of it can have the opposite effect.

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The Physical Activity Guidelines for Americans emphasize the importance of regular exercise. An active lifestyle may protect against heart disease and diabetes, reduce depression and improve your sleep. Aim for 150 to 300 minutes of moderate-intensity cardiovascular training or 74 minutes of high-intensity aerobic exercise per week. Squeeze at least two strength-training sessions into your weekly routine.

Working out for more than five hours, or 300 minutes, a week is even more beneficial, states the Physical Activity Guidelines for Americans. Just make sure you don't go overboard. Listen to your body, get adequate rest between training sessions and eat for your goals, whether that's fat loss, better overall health or sports performance. If you're an athlete, consider getting your hormones checked every few months.

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