Physical Activity, BMI, and Risk of Fecal Incontinence in the Nurses' Health Study.

Background: Higher body mass index (BMI) and low physical activity have been associated with increased prevalence of fecal incontinence (FI) in cross-sectional studies, but prospective studies examining the role of these factors are lacking. We sought to determine whether BMI and/or physical activity are associated with risk of FI among older women.

Methods: We prospectively examined the association between BMI and physical activity and risk of FI in the Nurses' Health Study among 51,708 women who were free of FI in 2008. We defined FI as at ≥1 liquid or solid FI episode/month during the past year reported in 2010 or 2012. We used Cox proportional hazards models to calculate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for FI according to physical activity and BMI, adjusting for potential confounding factors.

Results: During more than 175,000 person-years of follow-up, we documented 5954 cases of incident FI. Compared with women in the lowest activity category (<3 metabolic equivalent of task (MET)-hrs/week), multivariable-adjusted HRs for FI were 0.86 (95% CI 0.80-0.93) for women doing 3-8 MET-hrs/week, 0.78 (95% CI 0.72-0.84) for 9-17 MET-hrs/week, 0.76 (95% CI 0.69-0.83) for 18-26 MET-hrs/week, and 0.75 (95% CI 0.70-0.81) for 27 + MET-hrs/week (P = <0.0001). There was no association between BMI and risk of FI.

Conclusions: Higher levels of physical activity were associated with a modest reduction (25%) in risk of incident FI among older women. These results support a potential role of ongoing physical activity in the neuromuscular health of the anorectal continence mechanism with aging.

Translational Impact: These results support a potential role of ongoing physical activity in the neuromuscular health of the anorectal continence mechanism with aging.