Gait Medicine: an interdisciplinary field centered on walking as a vital sign.

Walking speed predicts survival, cognitive decline, and disability in older adults with a precision comparable to that of blood pressure-yet no single discipline organizes itself primarily around walking. The result is a clinical vacuum: when walking deteriorates from the convergence of weak feet, eroding confidence, and an unwalkable neighborhood, patients have no specialist to consult and clinicians have no integrative framework to apply. We propose Gait Medicine as an interdisciplinary field organized around a three-layer model-somatic (foot structure, neuromuscular function, sensory-perceptual systems, cognition, affect, and motivation), environmental (footwear and built environment), and meaning (social participation, cultural significance, and evolutionary origin)-with autonomous mobility as its superordinate concept, explicitly encompassing those who cannot walk. We define the field's conceptual boundaries, distinguish it from five adjacent disciplines, respond to three anticipated objections, and outline clinical implications including a Gait Clinic prototype and urban policy applications. The three-layer coupling model generates falsifiable predictions about integrative interventions that can be tested empirically. Gait Medicine does not claim to have discovered walking. It argues that medicine has not yet organized a discipline around it-and that the evidence, the patients, and the technology now make doing so both feasible and necessary.