Physical exercise for primary school girls can make their first menstruation later than that of ordinary girls. Even regular exercise after menstrual cramps can lead to menstrual disorders. Although menstrual delay and menstrual disorder are considered abnormal, some experts believe that this is not a bad thing because it can prevent the body from being hurt by sex hormones.
Dr. Ruth of Harvard University Health Center said that the development age of American girls has gradually advanced in this century. At present, girls' first menstruation is generally 12.5 years old, but when playing tennis, running, basketball and rugby, the average age of first menstruation can be delayed to 15.5 years old.
Ruth believes that the more frequent menstrual cycles a woman has in her life, the greater the risk of breast cancer. Many women in the United States die of cancer, so any way to delay menstrual cramps can reduce the risk of cancer. She said: "Regular exercise from primary school has long-term benefits, because it can not only reduce the risk of breast cancer in women, but also reduce the risk of diabetes and reproductive organ cancer."
Statistics in the United States in recent years show that the risk of dying from breast cancer is increasing. Dr. Jack said that the occurrence and development of breast cancer may last for four years, and whether exercise during development is related to the occurrence of menopausal breast cancer. After studying 5393 women who graduated from American 10 universities, Ruth found that the proportion of women who insisted on physical exercise in universities or middle schools was only about half that of those who did not exercise in their later years, while those who had delayed menstruation or menstrual disorders during adolescence did not find any adverse consequences.
Boston surgeon, who won the Olympic bobsled championship, said that teachers and parents always think that delayed menstruation or irregular menstruation is abnormal, while young athletes think that this situation is a normal physiological adaptive response. It is harmless to delay menstruation because of exercise.
The relationship between exercise and fertility is very complicated. Experts believe that women who exercise too much and are muscular can't get pregnant because the body can't provide enough nutrition for the fetus. They must take less exercise and increase fat to have children. Studies have shown that thin women secrete more inactive estrogen than fat women. Androgen is not only the key hormone of fertility, but also an important factor leading to breast cancer and reproductive system cancer.
Only experts believe that thin women can get pregnant, but they secrete little active estrogen, thus resisting the growth of breast cells and reproductive system tissues, reducing abnormal cell division and reducing the chance of cancer. Some researchers believe that male excessive exercise reduces the secretion of androgen and interferes with the production of semen. However, the influence of excessive exercise on male fertility is not as great as that on women.