Gait stability in postpartum runners: A pilot study to inform the development of evidence-based return-to-running guidelines following childbirth

Introduction & Purpose Only 75% of female runners return to running following pregnancy and childbirth (Moore et al., 2021). Reported barriers for returning to running postpartum include pelvic floor dysfunction, musculoskeletal pain, and fear of movement (Moore et al., 2021), all of which may trigger or be the result of compensatory running gait adaptations. Provenzano and colleagues (2019) showed limited transverse plane trunk and pelvis rotations during running in the first weeks of the postpartum period and speculated that this adaptation may be an attempt to compensate for lower gait stability and higher perceived injury risk. It is unknown, however, whether reduced gait stability is still present greater than four months post-birth when current Austrian physical activity guidelines consider a return to high-impact sports possible (Ring-Dimitriou et al., 2020). Next to musculoskeletal and psychological rehabilitation, one possible approach to improve gait stability in postpartum runners may be through footwear interventions. This is based on evidence for an improved local dynamic joint stability during running with shoes of reduced midsole thickness – possibly due to superior sensory feedback from the running surface (Frank et al., 2019). The goal of this pilot study was to test the hypothesis that gait stability, quantified by trunk rotation excursion and local dynamic gait stability during running, is lower in postpartum (PP) runners more than four months post-birth compared to nulliparous controls (CTR). Further, to explore the association between measures of gait stability, fear of movement, and the choice of running footwear to help inform return-to-running guidelines. Methods Twenty-one female runners (n = 12 PP, n = 9 CTR) self-reported their demographics, running habits, birth and postpartum history (PP only) and fear of movement according to a German version of the 11-item Tampa Scale of Kinesiophobia (TSK; Woby et al., 2005). Running kinematics were quantified using a 17-sensor inertial motion capture suit (Xsens Link, Movella, Enschede, NL). All runners ran on a treadmill at a self-selected speed for five minutes and in four running shoe conditions (their own running shoes plus three models varying in midsole thickness and stiffness). Trunk rotation excursion was quantified from the average range of motion of the thorax segment in the transverse plane for the last three minutes. Local dynamic gait stability was assessed using the local dive