Hip Biomechanics During Running Are Similar Between Continent And Incontinent Runners

PURPOSE: Stress urinary incontinence (SUI) is prevalent among female runners. Hip strengthening exercises are effective in decreasing SUI in the general population, likely due to the anatomical link between the pelvic floor muscles and the obturator internus muscle. Because of the connection between the hip and pelvic floor, decreased hip control during running may place a greater demand on pelvic floor muscles, potentially contributing to SUI. Assessing running hip mechanics may provide insight into treatment strategies for runners with SUI. Females with SUI have greater hip abduction moments and hip adduction angles during walking compared to continent females, but these variables have not been studied during running. The purpose of this study was to determine if there is a difference in hip adduction excursion and hip abduction moment between continent and incontinent female runners. METHODS: Female recreational runners who were continent (CON, n = 34, 42.7 ± 8.6 years) and those self-reporting SUI during running (SUI, n = 16, 45.3 ± 7.5 years) ran at self-selected 5 K race pace (CON: 2.9 ± .4 m/s, SUI: 3.0 ± .4 m/s) on an instrumented treadmill (Motek Medical). Hip adduction excursion (ADDexc) and peak hip abduction moment (ABDmom) of the dominant limb stance phase were calculated from reflective markers on the pelvis and lower extremity (Vicon Nexus & Visual3D). Independent t-tests (p < .05) were used to determine if there was a difference in ADDexc or ABDmom between SUI and CON. RESULTS: ADDexc in CON = 5.9 ± 2.8°, SUI = 6.3 ± 2.7°. ABDmom in CON = 1.4 ± .3 N/kg, SUI = 1.5 ± .4 N/kg. Results of the independent t-tests revealed no significant differences between CON and SUI for ADDexc (p = .642, Cohen’s d = .15) or ABDmom (p = .248, Cohen’s d = .28). CONCLUSIONS: There were no significant differences in ADDexc or ABDmom during the stance phase of running between continent and incontinent subjects in this group of female recreational runners. One possible reason for the lack of significant differences is that SUI was reported as mild in most of the SUI participants (n = 14), and only moderate or severe in 2 participants. The lack of difference in hip mechanics between continent and incontinent runners suggests that other factors may contribute to urine leakage during running, such as pelvic floor muscle strength, power, and/or coordination.