What features of the built environment matter most for mobility? Using wearable sensors to capture real-time outdoor environment demand on gait performance.

BACKGROUND A growing body of research has demonstrated relationships between built environment characteristics and outdoor mobility. However, most of this work has relied on composite scores of the built environment. RESEARCH QUESTION Which properties of the outdoor built environment are associated with the greatest change in gait metrics in a real-world setting? METHODS 25 community-dwelling adults from Southeast Michigan were equipped with mobile inertial measurement units and walked a 1300-meter outdoor course with varying environmental demands. Environmental properties were documented in sections of the course using the Senior Walking Environmental Assessment Tool. Gait speed, left foot cadence, and stride length were used to identify the built environment properties under which mobility was most challenged using linear mixed models. We hypothesized that subjects would adapt to demanding environments by decreasing gait speed, increasing cadence, and shortening stride length. RESULTS Properties of the built environment were significantly associated with changes in gait speed, left foot cadence, and stride length. Properties that were most important for predicting gait speed included slope, sidewalk condition, and presence of holes. Sidewalk slope, bumps, and the presence of a curb cut were all significant predictors of left foot cadence. Mean stride length of the outdoor course was significantly associated with the section's condition, slope, holes, bumps, width, and the presence of grooves and bumps at a curb. SIGNIFICANCE Associations between environmental properties and gait parameters were differential across the three mobility outcomes. When examining which properties of the built environment are challenging to navigate it is important to understand the relative influence of specific properties on gait metrics. Knowledge of which built environment properties are barriers for walking behavior is critical for the design of inclusive sidewalks and streets.