Prevalence and frequency of menstrual cycle symptoms are associated with availability to train and compete: a study of 6812 exercising women recruited using the Strava exercise app.
Level 4 - case-series / case-control
Cross-sectional survey
PubMed 33199360 · doi:10.1136/bjsports-2020-102792
What was done
A 39-part localized survey was completed by 6,812 adult exercising women of reproductive age (mean age 38.3 ± 8.7 years) not using combined hormonal contraception, recruited through the Strava exercise app across seven geographic regions (Brazil, France, Germany, Spain, UK/Ireland, USA). The study evaluated exercise habits, menstrual status, symptom frequency, medication use, and perceived impacts on exercise and work, compiling 18 symptoms into a Menstrual Symptom index (MSi, range 0 to 54).
What was found
The most prevalent symptoms were mood changes/anxiety (90.6%), tiredness/fatigue (86.2%), stomach cramps (84.2%), and breast pain/tenderness (83.1%). After controlling for BMI, training volume, and age, each unit increase in MSi was associated with a greater likelihood of missing or changing training (OR 1.09, 95% CI 1.08 to 1.10; p <= 0.05), missing a sporting event or competition (OR 1.07, 95% CI 1.06 to 1.08; p <= 0.05), absenteeism from work or academia (OR 1.08, 95% CI 1.07 to 1.09; p <= 0.05), and pain medication use (OR 1.09, 95% CI 1.08 to 1.09; p <= 0.05).
Why it matters
This study provides large-scale multi-country data establishing that menstrual cycle symptom burden frequently disrupts exercise participation, competition availability, and work capacity in active women.
Limits
The study relied on a convenience sample recruited through a single fitness app, creating selection bias. Data were retrospective and self-reported, leading to potential recall bias. The cross-sectional design cannot establish causality, the MSi index was not formally psychometrically validated, and findings cannot be generalized to women using combined hormonal contraception.