Amenorrhea and oligomenorrhea risk related to exercise training volume and intensity: Findings from 3,705 participants recruited via the STRAVA exercise application

The physiological underpinnings of amenorrhea/oligomenorrhea (AO) among exercising women are complex and incompletely understood. Objectives: To investigate associations between self-reported exercise training habits and AO among physically active women. Design: A cross-sectional survey was completed by 3,705 women (median age = 40 years [Quartile 1, Quartile 3: 30, 45], body mass index [BMI] = 22.1 kg/m2 [20.5, 24.2]) representing multiple nationalities and sports via the STRAVA exercise application. Respondents selected the amount of time they participated in low intensity (LIT), moderate intensity (MIT), and high intensity exercise training (HIT) domains per week. AO was defined as self-reporting 10 menses in the last year. Method: Associations between weekly exercise volume for LIT, MIT, and HIT and AO were modeled with univariate logistic regression models, followed by adjustment for age and BMI. Results: AO prevalence was 16% (n = 576/3,705), with no difference by country of origin or most sport modes. In adjusted models, participating in LIT 7 h/week or MIT 6 h/week was associated with 1.43 (95% CI:1.04 - 1.96) and 1.46 (1.10 - 1.95) greater odds of AO compared to 2 to 3 h/week, respectively. Similarly, HIT 5 h/week was associated with 1.41 (1.03 - 1.92) greater odds of AO compared to 1 to 2 h/week. Participating in LIT for 30 min/week compared to 2 to 3 h/week was associated with reduced AO odds (0.65 [95% CI: 0.44 – 0.94]). Conclusions: Taken together, these associations suggest greater weekly exercise volume, irrespective of intensity, may increase AO risk among habitually active women.