Is there a link between exercise and early menopause?

Lifestyle factors such as exercise can influence the timing of menopause. But so far, the results of prior research have been inconsistent. Some studies have shown that women who are physically active may be at a lower risk of menopause before the age of 45, while other studies have shown evidence of the opposite. To understand if physical activity is associated with early menopause, scientists from the University of Massachusetts conducted a study that limited the likelihood of bias to understand the relationship between exercise and the timing of menopause.

While no link has been found between physical activity and early menopause, the study suggests that environmental factors are associated with early menopause.

The study analysed data from 107,275 women. These women were followed from the time they joined the Nurses’ Health Study II in 1989 until 2011. The participants were US registered nurses aged 25-42 and they completed questionnaires about lifestyle and medical conditions every two years thereafter. They were asked about the amount of time they spent in recreational physical activity such as walking, running, cycling, racquet sports, swimming laps, aerobic activities, yoga, weight training and high-intensity activities such as lawn mowing. The researchers also collected information on age, race, ethnicity, education, height, weight and BMI, diet and the use of dietary supplements. Other information collected included the age when the women had their first period, whether or not they had been pregnant and how often, the use of oral contraceptives and hormone therapy as well as whether or not they smoked.

To assess the frequency, duration and intensity of the activities, the researchers multiplied the hours per week of each activity by its metabolic equivalent (MET) score to calculate the total MET-hours per week. One MET equals one-kilogram calorie per kilogram per hour (kcal/kg/h), which is the amount of energy expended by sitting quietly for an hour.

During the 20 years of follow-up, 2786 women experienced natural menopause before the age of 45. After adjusting for age, smoking and other factors, the researchers found no association between physical activity and early menopause. For example, when comparing women who reported less than three hours MET per week of physical activity and women reporting 42 or more hours per week, the researchers found no significant difference in the risk for early menopause. The amount of physical activity the women reported in their teenage years was also unrelated to the risk of early menopause.

While no link has been found between physical activity and early menopause, the study suggests that environmental factors are associated with early menopause. The researchers found that a higher intake of calcium and vitamin D from dairy foods as well as a higher intake of vegetables was associated with a lower risk. However, a higher intake of animal protein is not associated with a lower risk of early menopause. Cigarette smoking is associated with a higher risk, as well as being underweight.

Source: Human Reproduction