Exercise and Risk for Early Menopause: The Final Word?

George W. Citroner

Disclosures

September 26, 2018

What We Thought: Exercise Linked With Early Menopause

A groundbreaking new study[1] may disprove prior research linking exercise with early menopause.

Previously, researchers in Japan[2] tracked 3115 premenopausal women, aged 35-56 years, for more than 10 years to find that those who exercised between 8 and 10 hours weekly were 17% more likely to begin menopause in their 40s or younger (considered early menopause) than the more sedentary women.

Seven years after that controversial study, new research on physical activity in women, with vastly more participants and a 20-year follow-up, appears to invalidate the findings of Nagata and colleagues. This new study was published online August 21 in Human Reproduction.[1]

Dr Elizabeth Bertone-Johnson, professor of epidemiology at the University of Massachusetts and director of the research, told Medscape, "Our goals for this analysis were to assess whether women who frequently engaged in physical activity during adolescence and/or adulthood had a lower risk for early menopause compared with women with low physical activity. Understanding this relation is important both for recommendations to women and for better understanding the pathophysiology of early menopause."

The Health Outcomes of Early Menopause

About 10% of women begin menopause before age 45 years, a phenomenon known as "early" or "premature" menopause.[3] Early menopause is linked to a higher risk for early death, osteoporosis, cardiovascular disease, and other health problems.

Tia Guster, MD, at Piedmont Physicians Obstetrics and Gynecology in Newnan, Georgia, explained that "[w]arning signs of premature menopause include hot flashes, infrequent menstrual periods, mood swings, and hot/cold temperature intolerance."

"We know that a women's cardiovascular risk increases after menopause and rapidly approaches that of men," said Elissa Gretz Friedman, MD, NCMP, director of the Menopause Center of New York at Mount Sinai.

Gretz Friedman added that there is also a considerable risk to bone health. "A woman begins to rapidly lose bone at menopause. With a younger age at menopause, this loss would begin earlier and would lead to increased risk for fracture, particularly hip fracture."

Physical Activity and Early Menopause 

As the largest study of its kind to date, the new study on physical activity and incident early menopause contradicts the findings of Nagata and colleagues.

Bertone-Johnson and colleagues analyzed data from 107,275 female nurses aged 25-42 years who were enrolled in the Nurses' Health Study II. The nurses completed questionnaires about lifestyle and medical conditions every 2 years and were followed prospectively from the time they joined the Nurses' Health Study II in 1989 until 2011.

Data were collected on such factors as race, ethnicity, age, education, height, the age when they had their first period, and whether they had ever been pregnant and how many times. They were asked whether they used oral contraceptives or hormone replacement therapy, their weight and body mass index, diet, and use of dietary supplements or tobacco.

Participants were also questioned about how much time they spent in various physical activities, such as walking, running, cycling, racquet sports, swimming laps, aerobic activities, yoga, weight training, and even household chores.

The hours per week of each activity was multiplied by its metabolic equivalent (MET) score to create total MET hours per week. One MET represents the amount of energy expended in 1 hour when at rest.

No Link Between Activity Level and Menopause

Only 2786 women (2.5%) experienced natural menopause before 45 years of age during the 20-year follow-up period.

No significant differences were found in the risk for early menopause between women reporting less than 3 MET hours weekly of physical activity and women who reported 42 or more MET hours weekly, which is equivalent to running more than 4 hours every week.

The amount of physical activity during their teenage years reported by the women was likewise unrelated to the risk for early menopause. After adjustment for age, smoking, and other factors, the findings strongly suggest that there is no association between physical activity levels at any age and experiencing early natural menopause.

Study Limitations

The study was limited by such factors as the fact that study participants self-reported their physical activity and menopausal status, and that they were all white.

The researchers say that repeated assessments of these factors every 2-4 years significantly reduced the likelihood of bias. Furthermore, they state that it's unlikely that the physiologic relation between activity and menopause varies by ethnicity.

Bertone-Johnson said, "Although one of the main limitations of our study is that activity was self-reported, rather than directly measured via actigraphy or other technologies, activity measured by our questionnaire had been shown to have good validity and reproducibility compared with physical activity diaries, and has been strongly associated with other health outcomes in the Nurses' Health Study II. Thus, we do not expect that misclassification of activity levels was sufficient to obscure an important association of exercise with early menopause."

What Predisposes Women to Early Menopause?

Guster commented that although exercise didn't appear to have any influence on age at menopause in this study, "[c]ertain factors can predispose someone to experience premature menopause. These include a family history of early menopause, smoking, and being underweight."

"Chemotherapy can affect the ovaries and lead to an early menopause, and some women go through an early menopause simply owing to surgical removal of the ovaries. Any surgery near the ovaries, such as a tubal ligation or hysterectomy, may lead to earlier menopause, perhaps by compromising the ovarian blood supply," explained Gretz Friedman.

Reducing Risks and Consequences of Early Menopause

Gretz Friedman said, "To date, age of menopause is not something women can intentionally change, although the consequences of menopause-related low estrogen levels can be treated with hormones." She added that hormone replacement therapy is often recommended to women experiencing an early menopause, and that hormonal treatment until reaching the age of an average menopause could be the best course of action for a woman who is already experiencing early menopause.

Bertone-Johnson offers practical advice: "We have found in our other work that high dietary intake of vitamin D and calcium from dairy foods, and also high vegetable protein intake, are both associated with a lower risk for early menopause."[4]

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