Exercise can cause hormonal changes in women. Some changes are considered beneficial, while others can have a negative effect. In most cases, moderate amounts of exercise produce positive effects on hormones, while excessive amounts of exercise can actually harm the body by throwing off normal hormonal patterns.
Human Growth Hormone
Human growth hormone, or HGH, is secreted in the body following a circadian rhythm. The two most powerful nondrug ways to stimulate HGH is through sleep and exercise. Human growth hormone is in charge of growth itself as well as the turnover of muscle, bone and collagen. It has a role in metabolic functioning, including increasing fat metabolism and maintaining a healthier body composition in later life. According to "Sports Medicine," exercise-induced growth hormone response, or EIGR, is well recognized. Both resistance training and endurance exercise play a significant role in increasing EIGR.
Physical and emotional changes that are a part of premenstrual syndrome occur in nearly 80 percent of women who menstruate. These changes occur due to the hormonal fluctuations within the menstrual cycle, but are generally caused by declining levels of progesterone before the period. Women Living Naturally focuses on diet and dietary supplements and exercise as nondrug ways to alleviate PMS symptoms. The website suggests that women who exercise experience fewer bouts with anger, depression and other PMS symptoms, including stress. It encourages women with PMS to exercise 20 to 45 minutes daily or at least three times a week.
Some women cease having monthly periods when they exercise excessively. Certain types of exercise, such as long-distance running and ballet dancing, are associated with low body weight. The combination of low body weight and excessive exercise cause the body to believe it is in a starvation state. When nutrition does not counteract the calories burned by exercise, the body begins to shut down systems not required for survival, including the reproductive system. Women with exercise-induced amenorrhea are deficient in estrogen, which can cause infertility, vaginal and breast atrophy and osteoporosis. When prolonged, it may increase the risk of heart attack later in life. This state can be reversed by increasing caloric intake or taking estrogen in the form of pills or a patch.
Lower Breast Cancer Risk
BreastCancer.org cites studies showing a link between moderate-to-vigorous exercise and lowered risk of breast cancer. Researchers indicate regular intense exercise reduces breast cancer risk by lowering estrogen levels. One such randomized trial was reported in the "Journal of Clinical Oncology" in February 2010. Researchers followed 320 sedentary postmenopausal women, ages 50 to 74, for one year. Half did 225 minutes per week of aerobic exercise, while the other half maintained their usual activity level. At the end of one year, both estradiol and free-estradiol levels were lower in the exercise group. The researchers say the reductions helped lessen the risk of postmenopausal breast cancer.