Physical activity and age at natural menopause

Background: In a previous cross-sectional study we reported that lifelong heavy physical activity was associated with earlier age at natural menopause (ANM). The current report is to confirm and extend these findings.
Methods: Between 09.2006-02.2008, a convenience sample of 1106 women, born between 1946-1962, who had no history of major chronic disease and conditions that may obscure the determination of ANM were recruited for a cross-sectional study in Isparta. A detailed assessment of premenopausal exposures including health related factors and lifetime lifestyle factors was performed. Cox proportional hazard modeling is used to determine predictors of ANM.
Results: Out of 1106 women, 508(45.9 %) are postmenopausal. Median ANM is 52. The mean duration of premenopausal lifetime weekly moderate-vigorous physical activity is 5.4 ± 3.9 hours/week. Moderate-vigorous physical activity>12 hours/week is reported by n=76 women. N=572 women reported premenopausal ever engagement in activities involving running or jumping. Premenopausal avarage weekly duration of such activities for all women was 0.23±0.39 hours/week. In a multivariate model including variables related to sun exposure and physical activity as predictors, moderate-vigorous physical activity >12 hours/week is independently associated with an earlier ANM. Interestingly premenopausal ever engagement in running or jumping independently predicts a later ANM but this effect weans and reverses with increasing weekly duration of such activities resulting in an earlier ANM for those running or jumping for >1.4 hours/week.
Conclusions: Moderate-vigorous physical activity above a treshold predicts an earlier ANM. On the other hand, premenopausal engagement in activities involving running or jumping in moderation may predict a later ANM, whereas an excess of such activities predicts earlier ANM. To our knowledge this is the first study to characterize the association between physical activity and ANM in depth and to suggest a bi-directional association between running-jumping and ANM. Supported by TUBITAK-106S079(SBAG-3357)